test 3 Flashcards
short-term homeostasis of REM sleep example
- A lengthy REM sleep episode exhausts the homeostatic drive for REM sleep, so there is time for a long NREM sleep episode before the independent drive for REM sleep again reaches threshold and initiates REM sleep again
- A short REM sleep episode does not exhaust the drive for REM sleep, so only a short NREM sleep episode can follow before the REM sleep initiation threshold is reached again
Disrupted sleep»_space;
more pain the next day in people with fibromyalgia and burn injuries
why have two regulatory mechanisms?
- Circadian clock sets the timing for sleep etc. based on the patterns that have served a species well over evolutionary time
- But circadian system can fail in unusual circumstances (e.g., inadequate food, water, or sleep)
- Homeostatic mechanisms function as an emergency backup system
homeostasis?
the mechanism by which organisms respond to spontaneous or externally induced changes in their internal environments by corrective actions that restore the initial condition
Sleep deprivation prevents the…
typical morning decline in Aβ levels in CSF
hypersomnia symptoms
- Primary complaint is daytime sleepiness where the cause is not disturbed nocturnal sleep or misaligned circadian rhythms
- Daytime sleepiness: the inability to stay alert and awake during major waking episodes of the day, resulting in unintended lapses into sleep
*not narcolepsy
hypocretin =
associated with arousal
issues comparing sleep patterns method
- EEG on animals must be done in a lab-type setting. Lab environment effects sleep parameters compared to natural environment.
- Actigraphy in natural habitat can change behaviour and effect measurements
- Cerebral mass (brain size) does not necessarily mean more neurons or increased cognitive function
disk over water: deprivation/approach/controls
- ‘total’ or stage-selective; short or very long-term (weeks)
- passive (& active); sleep onset triggers requirement to wake & walk briefly to avoid falling into shallow pool
- control animal in same environment loses much less sleep
two process model of sleep regulation?
homeostatic model of sleep regulation
sleep spindles are involved in
regulating sensory filtering and attention while awake
REM sleep deprivation leads to
increased REM sleep amounts on recovery nights
Ratities REM sleep
(diverse group of flightless, large, long-necked, and long-legged birds)
- are primitive species and show mixed REM sleep features
Reciprocal causal relationship between sleep disturbances and anxiety
-Cognitive behavioural therapy aimed at reducing insomnia symptoms given to those with cooccurring anxiety»_space; significant reductions in reported levels of anxiety
-Cognitive behaviour therapy aimed at treating anxiety symptoms in GAD»_space; reductions in reported insomnia symptoms
Observational studies have consistently found that adults with short sleep have….
higher weight
….but increasing the amount of REM sleep does not…
result in rebound decreases the following night
unihemispheric sleep
electrophysiologically defined sleep in one cerebral hemisphere while the other hemisphere remains awake
SWA is associated with
increase flow of blood and CSF into human brain
pro-inflammatory leukocytes example
interleukin (IL)-1, IL-6, IL-12, and tumour-necrosis factor (TNF)-⍺
ostrich REM sleep
- Brainstem REM sleep features (i.e., eyes closed, REM, reduced muscle tone in neck)
- Forebrain slow waves or an activated EEG
Physiological changes in rats in DOW studies observed after…
NREM and REM sleep deprivation (although more slowly with REM sleep deprivation)
Daily rhythm with increasing levels of Aβ in the CSF during….
daytime waking and lowest levels immediately after a night’s sleep
rats results?
not consistent, could be affected by strain or methods used
association between poor regulation of glucose and delayed chronotype/increased social jetlag also supported by
PSG and actigraphy studies — not just self report
paradoxical insomnia symptoms
Occurs in <5% of insomniac patients
Sleep State Misperception
by the early 21st century, only ___ of mammals sleep studied electrophysiologically
Only 3% of mammals’ sleep studied electrophysiologically
anticatapletics
medications that inhibit serotonin or norepinephrine reuptake (e.g., antidepressants)
evidence that SWS is particularly important for regulating glucose metabolism
Disrupting SWS with noise over 3 nights»_space; increased insulin resistance proportional to the amount of SWS lost, despite normal total sleep durations
Even a single night of SWS reduction»_space; increased insulin resistance
But not reductions in REM sleep
Finish the sentence: REM sleep and endothermy seem to be linked
seem to be linked in opposite ways phylogenetically and developmentally.
what is the relationship between altricial mammals and endothermy?
complex. REM sleep and endothermy seem to be linked in opposite ways phylogenetically and developmentally.
- endothermy generate REM sleep
- however, altricial mammals which are essentially ectothermic at birth show large amounts of REM sleep that steeply declines
Sleep enhances the flow of…
CSF through deep regions of cortex by expanding the volume of the interstitial space surrounding cells
Short-term sleep loss has been shown to:
- Suppress pro-inflammatory cytokines (e.g., IL-6)
- Decrease number of natural killer cells (NK cells, -leukocytes that respond to infections and tumours)
- Increase levels of anti-inflammatory cytokines
regulating REM may appear to be…
a complex process
phocidae sleep
Only bilateral sleep
Remain submerged for long periods of time without breathing
short-term homeostasis theory proposes that
- REM sleep and NREM sleep are each regulated by independent homeostatic mechanisms within a sleep period
- REM sleep is the target of homeostatic regulation and NREM sleep “fills in” the gaps between REM sleep episodes
Short term = within a cycle
Chronic, medicated, first episode, and drug-naive people with schizophrenia show…
deficits in performance of a sensorimotor filtering task
Loss of N2 sleep and sleep spindles could impair working memory, deficits in sleep-related memory consolidation
Strong correlations between the length of the NREM-REM sleep cycle and:
Metabolic rate (-0.82)
Brain weight (+0.89)
Improved sleep may act on…
immune system and depression
small platform (flowerpot): deprivation/approach/controls
- principally of REM sleep; short or long term
- passive; risk of falling into shallow pool after REM sleep onset
- multiple platforms permitting movement but not sleep, or large platforms permitting sleep
randy gardner
Deprived himself of sleep for 11 days (264 hours), lost roughly ~74 hours of usual sleep time
people who never sleep or sleep very little…
Most accounts are anecdotal with no objective evidence
sleep apnea treatment
CPAP machine that forces air through airways although that may disrupt sleep
Studies show treatments aimed at treating depression were more effective when combined with ….
CBT for insomnia
blood pressure appears to be under…
circadian control and further reinforced by sleeping
Abnormal glucose regulation reflects…
inadequate responses to the effects of insulin
anti-inflammatory leukocytes example
IL-4, IL-10, IL-13
sleep terrors usually occur during
Usually occur during transitions between N3 or N4 sleep and wakefulness
Episodes typically last a few minutes but can last up to an hour
Often occurs along with sleep walking
delta waves Hz and V
delta waves: 1-4 or 4.5 Hz, amplitude of 75-140V
Rise and fall of SWA during sleep periods in both panels
> > homeostatic mechanisms within a sleep period (i.e., drive to produce SWA gradually decreased)
bird species uni vs. bi sleep seems to be
modulated by the threat of predation
depression and sleep
-Most people with major depression find substantial changes in sleep
-Earlier onset of REM sleep in someone with depression
-Higher percentage of REM sleep relative to total sleep time in people with depression
-Seeing a lot more arousals
-Waking up really early
-Very disturbed sleep
-Large reduction in SWS
insomnia treatments
Stimulus control therapy - idea that you form associations between being in bed and sleeping. If you form an association between being in bed and not sleeping, that needs to be counter-conditioned
Sleep restriction
Relaxation
Cognitive therapies
Paradoxical intention
Sleep hygiene education
Behavioural intervention
Medication
Benzodiazepines
Melatonin agonists
Antidepressants
Antihistamines
carnivores
less vulnerable to predation. Eat energy-rich foods, can afford to sleep and conserve energy for many hours of the day (12-15 hours total)
as the day goes on, the drive for ____ increases
SWS
metabolic syndrome may take…
years to develop
tamaki studied
Studied people experiencing a “first-night effect” while sleeping in a lab
hypersomnia
some people very rarely experience hypersomnia with an episode of depression, where they sleep way more than baseline
when modelled, the level of process S reflects
- the degree of physiological need for sleep
- Current degree of sleepiness
- Predicts the amount of SWA that will be generated when sleep occurs
oleksenki results
Hemisphere that was allowed to sleep freely showed no increase in sleep duration while the other hemisphere was sleep deprived
- During recovery period, there were increases in delta-wave sleep only in the sleep-deprived hemisphere
- Increase in rate at which sleep alternated between hemispheres during recovery period
- illustrates independence of sleep production and sleep need in the two hemispheres
there is a serial positive correlation for
There is a serial positive correlation, but it goes the other way. Length of NREM sleep episode is determined by length of proceeding REM episode (flipped).
- REM —> NREM
Sleep duration association with mortality complicated by:
1.Most studies rely on participants responding to surveys about sleep length, asked in different ways
2.Very few assessments (subjective or objective) obtained in most studies
3.Potential hidden confounders
Ability of birds to implement unihemispheric sleep as needed is likely facilitated by
- Strong visual decussation in the chiasm
- Few interhemispheric connections
- Strongly lateralized eye positions
NT involvement in sleep and depression
-Early onset of REM sleep in those with major depression consistent with reduced 5HT and NE activity
-Drug treatments for depression (SSRIs, SNRIs) suppress REM sleep production
-Expected because those NT oppose REM sleep and are in SSRIs
lange et al hep A results
- People were immunized against hepatitis A
- Group 1: kept awake overnight
- Group 2: slept freely
–> Group 1: blunted antibody response
large mammals retain…
heat more effectively and therefore need to sleep less.
PSG studies and pain
- Amount of SWS an important predictor of next-day pain
- Alpha activity bursts during SWS associated with increased pain reports by people with fibromyalgia
- SWS is very important
rats, no rats survived more than
32 days
paradoxical insomni
complain little or no sleep most nights, but without objective sleep disturbances and no daytime impairments
Otariidae are
fur seals
miller study
Measured under water activity level of 59 sperm whales using data-logging tags
issues comparing sleep patterns among spcies
Most studies are correlational — otherwise you would have to alter something or change their evolution pattern
Not causation!
lange et al study topic
hep A
_____ and _____ are risk factors for vascular disease, independent of increased daytime and average 24-h blood pressure
Non-dipping and elevated nighttime blood pressure
total sleep loss in people signs
Abnormal eye movements
Inability to show visual convergence
Nausea
Abnormal sensory and reflex thresholds
Growth of lymphoid tissue in the throat
Cardiac murmur
Mood changes
Ataxia
Irritable, uncooperative
Memory lapses
Difficulty concentrating
Hallucinations
Mild astereognosis
Dysnomia
pain is usually caused by
tissue damage
tamaki results
- found increased vigilance and reduced NREM activity sleep depth only in the left hemisphere
- Presented auditory stimuli to the left and right hemispheres
- Found EEG and behavioural responses triggered at higher probability and shorter latency with stimuli presented to left hemisphere compared to right hemisphere
- Maybe localized EEG differences during sleep evolved over time
patrick and gilbert study
Kept three healthy young men awake for ~90 hours (3 ¾ days)
Depression
Major depression
Sustained negative mood
Reduced energy
Sleep problems
Loss of enjoyment of previously pleasurable activities
Insomnia
Does improving sleep improve depression?
Will help a lot with some of the symptoms, not a cure
Groups ancestral to all mammals (and birds?) may have shown only _____ during sleep (e.g., like reptiles!)
slow waves
Mechanism linking poor sleep to increased pain …?
No one mechanism, lots of things going on
schizophrenia and sleep spindles
> > Not a product of medication effects
Characteristic of early as well as chronic phases of schizophrenia (not deterioration of brain function)
why did brainstem REM sleep evolve in the first place? why did cortical desynchronization (REM) evolve later?
we dont know
homeostatic regulatory system for sleep depends critically on…
feedback (process S)
extremely short sleep is ____ and is _____
not a conscious choice; rare, genetically determined phenotype
what happens if you sleep later into the day
If you sleep later you may feel you have more dreams when you wake up
bipolar disorder – depressive episodes
- Sleep disrupted by wake episodes
- SWS reduced, REM sleep modified (earlier onset, higher density)
- More extreme sleep changes than those with unipolar depression
rem sleep and endotherms
- Remember, it is generally accepted that reptiles do not generate REM sleep
- Reptiles are ectotherms
- Is REM sleep tied to endothermy?
Elegant Crested Tinamou REM
- Brainstem REM sleep features
- Forebrain activated EEG
Non-dipping is associated with
Sleep apnea
Insomnia
Cardiac arrhythmias
Neurodegenerative diseases
sleep state misperception
ondition in which people perceive themselves to be awake for most or all of a night, even though they are objectively asleep for most of that period
by the early 21st century, only ___ of vertebrates sleep was completely assessed
0.06% of vertebrates’ sleep completely assessed
sleep disorders affect ____, some people experience disturbed sleep ___, others ______
large proportion, periodically, chronically
rheostasis?
Working together, they allow for rheostasis: The regulation of some aspect of a biological organism in a changing environment
people showing sleep state misperception also have high score for…
anxious rumination, depression, and poor coping skills
large mammals (rem)
Large mammals»_space; low metabolic rates and large brains»_space;longer NREM-REM sleep cycles
what is species adaptation related to
ecological pressures under which a species evolved
serial positive correlation direction
REM —> NREM
what about elephants vs. rabbits
- Elephants have few predators but they sleep very little, diet is quite energy poor
- Rabbits have a lot of predators and sleep a lot
smith et al study results
Group 1: pain and analgesia unaffected
Group 2: increased pain reports, impaired analgesia (feeling more pain)
Risk of developing hypertension increased with…
self-reported short sleep and insomnia complaints
insulin is released in response to
increased blood sugar following food intake
how long is an epoch
30 seconds
anti-inflammatory leukocytes are important for…
inhibiting inflammatory responses and promoting tissue healing
parasomnias are…
isorders of arousal, partial arousal, and sleep-stage transition
- Tend to occur when people are transferring through sleep stages
hatori et al study
Given access to high-fat diet all times of the day — developed fatty deposits in liver, elevated insulin levels
Given access to high-fat diet for 8h in daily dark phase
(Ate similar amounts)
Seems the circadian rhythm contributes to how glucose is processed
What happens when people develop increased insulin resistance
our cells are less sensitive to effects of insulin and not taking glucose in as easily, happens when you have had too much sugar. Your body starts to habituate to the signal and you end up with sugar left in your blood (hyperglycemia)
sleep apnea signs
Events are repeated dozens or hundreds of times a night
People may not even realize they have it — hard to know the extent to which they contribute because people often aren’t diagnosed
Monotremes (egg laying mammals) are endotherms but display
large variability in REM sleep
sleep and schizophrenia
Characterized by ‘positive’ psychotic symptoms (e.g., hallucinations, delusions) and ‘negative’ symptoms (e.g., cognitive and attentional deficits, flat affect, social withdrawal)
Studies have shown that subcortical dopamine dysfunction is a key mechanism in the pathophysiology of schizophrenia
Most studies include people currently medicated or recently withdrawn from antipsychotic medication
- Sleep features may be influenced by current or past medication
effects of total sleep deprivation: rats in the DOW procedure (over days and weeks of severe sleep loss)
Skin lesions
Severe disruption of body temperature regulation
Increased metabolic rates
Large increases in food intake
Weight loss
On second and third nights of REM sleep deprivation…
More interventions needed to prevent REM sleep early in the night
SWA could be
-art of the brain’s recovery process, or simply a reliable physiological correlate of an unidentified process
depression: effects on mediated by ___ loss, not by
SWS loss, not by reduction in total sleep time by equal amount
Fully terrestrial mammals (humans included) do not show…
unihemispheric sleep
combination of circadian and homeostatic systems allow for both
Predictive homeostasis
Reactive homeostasis
Working together, they allow for rheostasis
pain is the result of processes in…
peripheral sensory nerves, spinal cord, and the brain
Non-REM, stage 3 sleep (N3)»_space; defined as
epochs of sleep occupied by at least 20% delta waves
Chronic inflammation linked to development of
- Obesity
- Cancer
- Dementia
- Diabetes
- Vascular disease
- Depression
in studies of people limited to 3 or 4 hours of sleep per night for multiple nights, SWS amounts were…
almost completely preserved during the 3 or 4 hours of sleep permitted
promising drug treatment for depression and suicidality
Ketamine treatment for treatment-resistant depression and suicidality»_space; immediate change in glutamatergic neurotransmission»_space; increases SWS and promotes neural plasticity
These are for people who had nothing else work
pro-inflammatory leukocytes are important for…
fighting infections and disease
treatment for excessive daytime sleepiness
medications that increase the release, or inhibit the reuptake, of norepinephrine or dopamine have wake-promoting effects (e.g., Modafinil)
animals that are more primitive have…
only slow wave sleep
sleep walking tends to occur mostly during….
childhood
- Seen in 4-15% of children
- 1-2.5% of adults — tend to be quite dramatic
rats in DOW when did first rat die
after 11 days
REM sleep as a response to NREM, proposes that
- REM sleep is doing the cleaning, would expect both would be longer
- Would predict a positive serial correlation between REM and NREM
- Unfortunately, no evidence for this
Systematic reviews show mortality risk lowest for ____ nightly and increased for habitually shorter or longer sleep durations
7-8h
what is the physiological target
One or more changes in brain function that occur during extended waking and need to be reversed during recovery sleep
how long is an epoch
30 seconds
when is the best time to take drug treatments for blood pressure?
better taken at bedtime than in the morning
Physiology and anatomy of unihemispheric sleep
Acetylcholine levels are elevated bilaterally during both waking and REM sleep, but are strongly reduced during NREM sleep
Conflicting findings about responses of specific cytokines being increased in different studies in response to acute sleep loss
- Differences between sexes
- Sleep restriction for a week resulted in increased IL-6 and TNF-⍺ in men, but only IL-6 in women
the more SWS lost…
The more SWS lost, the higher the insulin resistance, despite if they had normal total sleep durations.
insulin sensitivity after chronic sleep restriction: 5hrs vs. 10hrs conditions
Very clear that healthy young men that only had 5 hours in bed a week had a much lower insulin sensitivity — struggling with blood glucose regulation after only a week
Complete sleep deprivation in humans and animals is virtually impossible
- Delay between onset of sleep episode and action by device or experimenter to wake the person/animal allow for brief sleep episodes
- Microsleeps (even with eyes open) are NREM sleep
- Isolated slow EEG waves while awake
- Increase in slower EEG activity during REM sleep periods
Bdr, SNAP-25
> > phase-advanced circadian rhythms, unstable rest-activity rhythms when housed in a light-dark cycle
Circadian organization normal under free running conditions
It’s not uncommon for one person to have…
several parasomnias
Homeostatic regulation of SWA operates both within…
a sleep period, as well as over longer time periods
bipolar disorder treatment
Most common treatment is lithium
- Reduces both mania and depression
- Reverses some sleep features (i.e., increases SWS, decreases REM sleep amounts)
large mammals =
lower metabolic rate»_space; shorter sleep durations
REM sleep in monotremes
rapid eye movements and loss of muscle tone
depression and sleep deprivation woman study 2
Seeing original high symptoms of depression, stay up all night and mood gets better. Then took a nap around 6am and symptoms went back to feeling quite depressed
Something about sleep that results in depressive symptoms increasing quite quickly again
5h being the restricted sleep condition meal patterns
eating little less for breakfast, lunch similar, dinner similar, daytime snacks similar, post dinner snacks way higher. People awake longer seem to eat way more — resulted in net weight gain over 5 days
ungulates
prey-species, vulnerable, tend to live in open areas. Tend to sleep in brief bouts and total sleep duration is very short (3-5 hours total). Because they are a prey they need to be alert. Diet is energy-poor, spend a lot of the time grazing in order to live.
differences in sleep patterns CAN be attributed to…
species’ adaptations to a specific circadian phase along with ecological factors like diet, shelter, predator-prey relations etc.
study two groups of women
4 h time in bed for 10 nights
8 h time in bed for 10 nights
- Looked at change in IL-6 (pro inflammatory cytokine — pro inflammation like a fever, trying to fight a virus — means more inflammation)
- Increased production of IL-6 in people that are sleep deprived and higher change in bodily discomfort
- Those getting less sleep have increased IL-6 and are more uncomfortable
- Potential relationship that the immune system is interacting with CNS and sleep
proportion of SWS sleep…
SWS starts heavy in the night and then decrease over time
sleep waking (somnambulism)
Person gets out of bed and engages in activities that normally occur during wakefulness
Occurs from sudden arousals from slow wave sleep (N3, N4 — SWS) (not during REM)
People sleep waking are herd to wake and do not remember the event
Tends to occur mostly during childhood
Rats chronically deprived of sleep (3-5 days of 4-6 hours of sleep, rather than their usual 10-12 hours) by means of forced walking
- Showed initial homeostatic increases in NREM sleep and/or SWA but these increases were lost over days as restriction continued
- After sleep restriction ended, showed large rebounds in REM sleep
- Rebounds in NREM sleep or SWA either did not occur or were delayed until hours later
» Allostatic processes?
insomnia symptoms
Difficulty falling asleep
Frequent awakenings
Inability to return to sleep after early morning awakening
people showing sleep state misperception may be good at _____ and poor at _____
- May be good at detecting and remembering being awake during the night
- Poor at detecting intervening sleep periods
night blood pressure meds reduce risk of…
heart attack, stroke, or dying of cardiovascular diseases over next 5.6 years relative to morning treatment
narcolepsy cause
Deficiency of hypocretin signalling, used by selective loss of hypocretin-producing neurons in the hypothalamus, likely result of autoimmune-related destruction
Onset of REM sleep triggered by ___ and opposed by ___ and/or _____ (NTs)
Onset of REM sleep triggered by acetycholine (Ach) and opposed by serotonin (5-HT) and/or norepinephrine (NE)
elephant cerebral cortex
Elephant cerebral cortex has twice the mass of the human cortex but includes only about 1/3 as many neurons
allostatis
Allostasis: a pattern of regulatory changes in response to stressful, persistent physiological challenges that cannot be addressed by the usual homeostatic mechanisms
Blood pressure normally (during day/at night)
rises during the day and falls (“dips”) at night during sleep
chronic short sleep
Most often associated with increases in pro-inflammatory cytokines
Weight gain in response to sleep deprivation may also depend on…
he time at which sleep-restricted participants eat
hyperglycemia greatly increases risk of….
heart disease, stroke, and Type 2 diabetes
Circadian Regulation
Forced desynchronization and nap studies show strong circadian regulation of REM sleep
SWA and naps
Higher amounts of SWA observed in naps taken later in the day compared to naps taken early in the day
People who spontaneously sleep 7-8 h seem…
unable to function on much less sleep over the long term
Bipolar disorder
Characterized by bouts of depression and low energy alternating at variable intervals with periods of high energy, irritability, euphoria, grandiosity, and behavioural disinhibition
REM sleep as a response to NREM sleep
- Cellular events that occur during NREM sleep create a neural state that must be reversed by generating REM sleep
- Drive for SWS/SWA is a response to being awake, drive for REM sleep is a response to the amount of NREM sleep produced
- Predicts that the longer the NREM sleep episode, the longer the subsequent REM sleep episode
stage 3 is the…
restorative stage of sleep
Long sleep associated with…
poor general physical health, low physical activity etc.
Drug-naïve people with schizophrenia showed…
specific reductions in N2 sleep
hypertension increases risk of…
cardiovascular disease, stroke, and organ damage (e.g., kidney failure, retinal damage)
miller findings
Sperm whales may use uni-hemispheric sleep during other low-level activities (i.e., ascent from depth)
… and use bihemispheric sleep during drift-dives
bottlenose dolphin sleep
- Each hemisphere sleeps total of ~4 h daily
- Periods of sleep alternate between hemispheres at approximately 1 h intervals
- Sleeps primarily at night
- Contralateral eye is closed during sleep
- Ipsilateral eye remains open
Studies show enhanced, more rapid, more sustained improvement in symptoms after single trial or repeated trials used in conjunction with:
-Antidepressant drugs treatment
-Bright light exposure
-Phase advances of circadian rhythms
narcolepsy with cataplexy symptoms
- Sudden overwhelming daytime drowsiness, sudden attacks of sleep after which the person feels refreshed
- Sudden muscular weakness triggered by strong emotions such as laughter, anger and surprise
- Other symptoms: distributed night-time sleep, hallucinations, sleep paralysis
Evidence suggests that _____ promotes Aβ accumulation
waking
CBT for insomnia symptoms (for people with insomnia and depression)….
improved sleep quality and reduced depressive symptoms as effectively as an antidepressant
patrick and gilbert findings
This study (and others like it) support the idea that sleep is homeostatically regulated and is an essential physiological need (like eating and drinking!)
the relationship between sleep deprivation and later recovery SWA does not prove that
generating SWA is itself is essential for the underlying restorative process
If people encouraged to sleep for very long periods…
some participants show an increase in SWA or SWS late in the sleep phase (~15 hours)
studying other drives requires…
removing or preventing access to external resources
miller results
- 80.6% of time spent in foraging dive bouts (depth, presence of echolocation clicks)
- 19.4% of time non-foraging shallow dives
- 31/59 whales conducted inactive shallow dives (“drift dives”) with inactive durations
phocidae are
true seals
recovery night
- Big drive to get more SWS, pushing off REM a bit
- Sleep onset is faster
-More sustained N3 sleep early in the night and increase amounts over first 6h of sleep - First REM episode delayed relative to baseline
what does melatonin do
dilates peripheral blood vessels (and promotes sleep)
Cappuccio et al. (2010)
Meta-analysis
Association with short sleep consistent regardless of age, sex, definition of short sleep, length of follow up, geographic location, adjustment for socioeconomic status
Association with long sleep varied
Sleep spindles are the product of…
interactions between the thalamic reticular nucleus (TRN), the cortex, and thalamic relay nuclei
Different methods used / timing of samples of immune system components
- Spontaneous level of immune system activity (circulating cytokine levels)
- Immune cells extracted and studied in vitro
- Mixtures of immune cell types with different functions studied together
- Chronically implanted venous catheters»_space; Increase in IL-6»_space; local response to the catheter
- Single needle sticks
- Daily rhythms in expression of immune system components
what proposes the REM/NREM serial positive correlation
- REM sleep has been allowed to clean up. It is cleaning up whatever accumulated during the NREM episode. As a result, the following NREM episode can be longer until a certain threshold has been reached when there is more of that stuff that has to be cleaned up. Once that has been reached, it flips back to REM sleep.
human participant study findings
- Likely because of the time of day at which the REM sleep occurred (7am-11am)
- Was not reduced on the following night
- REM sleep accumulated during daytime nap does not affect amount shown the following night
- Huge increase in REM could have occurred due to circadian rhythm — may not be reduced to any sort of drive because they are getting enough sleep. But could be explained by timing of day and circadian rhythm
Short sleep can affect weight regulation through
- Extra time for snacks
- Shifting food preferences toward high-calorie snack food
- Promoting food consumption during circadian night phase
voluntary (human): deprivation/approach/controls
- total or stage selective; short or long-term (days)
- auditory or physical stimulation to supplement cooperation
- free sleep
what is negative correlation attributed to?
Attributed to metabolism and energy balance in endotherms (animals that maintain an elevated body temperature using physiological mechanisms i.e., birds and mammals)
large mammals sleep __ than small mammals (herbivores)
less!
human total sleep and REM durations
Total sleep duration ~8 hours
REM sleep 2h (25%)
Arble et al study
Two groups of mice fed a high-fat diet for six week
Only eating during 12h light phase (when they would be sleeping, eg. us at night) — gained significantly more weight
Only eating during 12h dark phase (when they would normally be eating)
evidecne that SWA may simply be a correlate
Benzodiazepines (and related drugs that act on GABA receptors) suppress SWA and theta-band activity …. but still promote sleep in people with insomnia!
Increased insulin resistance/decreased insulin sensitivity
reduced uptake of glucose in response to insulin»_space; hyperglycemia and hyperinsulinemia (compensatory increases in insulin release)
Narcolepsy with Cataplexy - Treatment
Aimed at improving wakefulness and reducing cataplexy attacks, sleep disruption, sleep paralysis and sleep-related hallucinations
- meds
- lifestyle changes
hypersomnia is the
opposite of insomni
circadian clock works well in…
stable predictable environment
randy sleep patterns
on recovery nights, he showed big rebounds in SWA but also in REM sleep!
- 3 fold increase in REM sleep
what could cause increase in SWS
Unlikely to be homeostasis responses to sleep need
Evidence for a weak circadian influence that decreases wakefulness and promotes expression of sleep and SWA in the afternoon
Increases occurred near afternoon “dip” or siesta time
people who ‘never’ sleep, genetics:
mutation in regulatory gene DEC2
Further self-report studies show associations between poor regulation of glucose and
Delayed chronotype
Increased social jetlag
PSG studies are often conducted at…
one time point
Ultradian/Circadian influences
- The first REM sleep episode is gated by the onset of NREM sleep, while later episodes are controlled by an ultradian timer with a period >90 mins that scans across the 24 h cycle
- Suggests increased REM sleep frequency over the course of the night
- Once sleep has started and NREM starts, REM sleep keeps occurring on its own rhythm
people who ‘never’ sleep, PSG results
showed 1-3h of sleep over several nights
circadian regulation evidence
- SCN ablations in rats and monkeys show redistribution of sleep and wake into short, irregular bouts throughout 24 h period (evidence against idea of circadian regulation, must be homeostatic component)
- But total amount of REM sleep produced in the 24 h period remained unchanged
- There is long-term homeostatic regulation of the amount of REM sleep produced daily without circadian regulation, but timing of REM sleep depends on SCN
smith et al study methods
Two groups: wanted to reduce sleep by 50% of 3 nights
Group 1: sleep half usual duration (persevered SWS)
Group 2: repeated forced awakenings (reduced SWS) — not getting a full usual cycle because it keeps getting broken up
SWS is concentrated at beginning of night when you go to sleep, lessens in second half of sleep. If you get to sleep half of cycle then you are getting your SWS. People with forced awakenings had their SWS reduced quite a bit.
Then did a cold pressor task
Basic Rest Activity Cycle (BRAC)
- An underlying oscillator regulated REM sleep timing by opening a limited REM sleep “window” with a 90-110min periodicity (ultradian cycle = greater than 1 cycle per day)
- Regulates the timing of REM based on this limited window
- If someone had 20 minutes of NREM sleep, means there is 80 minutes left for REM sleep within that cycle — there is a negative serial correlation between REM/NREM (as one goes up the other goes down)
patrick and gilbert results
- Led to an increased desire to sleep and to an increased duration of later sleep
- Participants slept 10.5-15.5 hours during the night after sleep deprivation ended and felt fully refreshed afterwards (they recovered 16-35.5% of the sleep they had lost)
studying sleep deprivation, typical focus on
duration
predation risk and diet are therefore…
plausible contributors but alone, do not easily account for sleep patterns in general
some of the benefits from sleep may be achieved in…
weaker form during quiet, waking rest
Transgenic mouse models of schizophrenia show genes potentially linked to sleep
Bdr, SNAP-25
STOP
So being deprived of REM sleep results in…
increased REM sleep the following night
people that stay awake longer at night…
use more calories…!
- The longer you stay awake the more energy you are spending
SWA amounts are high…
immediately after sleep onset and decrease over the course of a night’s sleep
sleep deprivation and bipolar disorder
Sleep deprivation»_space; Small proportion of people in depressive episode of bipolar respond with a switch to (hypo)mania
gentle handling: deprivation/approach/controls
- ‘total’; short-term
- distraction, alerting
- free sleep
delta waves do not…
only occur in stage 3 sleep. but has to be up to 20% to be considered stage 3
- same with SWS
participants in patrick and gilberts study did…
not recover the total duration of sleep lost
metabolic syndromes
- Obesity (especially abdominal obesity)
- Dysregulated lipid metabolism (elevated cholesterol and/or triglycerides)
- Hypertension (high blood pressure)
- Disturbed glucose regulation
Otariidae sleep
- Mostly unihemispheric sleep with little REM sleep when in the water
- Paddle idly on their side at the surface of the water
- On land, show bihemispheric sleep and 5% REM sleep
- Sleep deprivation studies show specific drive for bihemispheric sleep
monotremes may represent…
early stages in the evolution of REM sleep in which REM and atonia, eye closed, etc. (brainstem REM sleep) occur along with cortical slow waves other than cortical activation (forebrain REM sleep)
Cross sectional and prospective population-based studies show
Self reported short sleep, long sleep, or sleep maintenance difficulties»_space; Increased risk of having or developing elevated glucose levels
- PSG studies on effect of SBDs on glucose regulation show mixed results
Actigraphy study with male and female adolescents, looking at insulin resistance in relation to their weekday sleep duration: findings
- Those with shortest sleep duration had highest insulin resistance, struggling to refute the most
- Those in group 4, sleeping the most, had the lowest insulin resistance — body is regulating sugar in their blood best
sleep terrors occur in increased frequency in individuals with
Variety of other disorders
Times of high anxiety fever, full bladder, stress, noisy environment, sleep deprivation, ADHD/autism
Practical implications in population-based observational studies, self-reports, actigraphy, PSG etc. make studying relationship between sleep and health….
difficult
attempts to console the child during night terrors can…
cause/increase panic and may prolong or intensify the episode
But in recovery sleep after sleep deprivation, may be obscured by…
immediate increase in SWS that delays the first REM sleep episode
alzheimers disease
neurodegenerative disease, most common cause of dementia
recovery sleep is deeper after…
deprivation and may allow more complete recovery than suggested by the duration of the recovery sleep
recovery sleep after a night of sleep deprivation includes…
more N3 sleep than a normal baseline night
small mammals =
higher metabolic rate»_space; longer sleep durations
experimental studies
Short-term metabolic changes in response to sleep restriction serve as surrogate markers for clinical conditions
The amount of SWA produced during sleep is…
strongly affected by the length of prior waking
SWA shown during naps
Antipsychotic medications reduce dopaminergic neurotransmission and… (on sleep)
-Increase total sleep amounts
-Reduce sleep disruptions
kleitman study
60 h of sleep deprivation»_space; hyperalgesia without increased sensitivity to light touch
Chronic pain can make sleep difficult, and
Sleep loss contributes to pain sensitivity
Benefits of ket treatment mediated by improvements in self-reported sleep:
Insomnia
Total sleep amounts
Nighttime restlessness
Early morning awakening
depression and self deprivation woman study 1
Over three experimental nights their rating of depression shows they are feeling pretty depressed
When they get to 19 hours awake (not sleeping for the night) — their clinical state goes to a normal baseline, leaning closer towards manic side but still normal
Sleep deprivation for three more nights continued the results
why may people with less sleep gain more weight?
Could be that increased caloric intake overnight means they are not as hungry at breakfast or could be that they are woken up really early at a weird phase in their circadian cycle and are not hungry
small mammals (rem)
Small mammals»_space; high metabolic rates and small brains»_space; shorter NREM-REM sleep cycles
Sleep deprivation results in
Increased total food intake
Preferences for high-calorie foods — particularly during extended waking at night
Short sleepers that stay up later tend to gain more weight
diagnosis of sleep disorders depends on…
symptoms, pathophysiology, body systems, natural circadian rhythms, chronotype, etc.
Human participants asked to sleep for 3 successive nights for 8 h, 12, h, and 8 h respectively: NREM findings
NREM sleep increased by ~32% during the 12 h sleep opportunity
Moldofsky and Scarisbrick study
Deprivation of SWS (but not REM sleep) in healthy subjects»_space; next-day hyperalgesia
monotremes REM sleep variability
Echidna = no REM sleep
Platypus = 6-8h REM sleep daily — among longest duration in mammals
what happens with SWS/REM over the day
Increase in SWS sleep later in the day, decrease in REM sleep (this is afternoon/early evening time)
roehrs et al study method
-Participants were healthy adults with unusually short sleep-onset latencies (falling asleep really quickly) — probably really tired, not getting enough sleep. People that are not sleeping well at baseline.
-Baseline: Measured how long it took them to withdrawal their finger from a hot stimulus
-Group 1: extended TIB
-Group 2: usual sleep duration (probably not enough)
-Measured how long it took them to withdrawal their finger from a hot stimulus again
two process homeostatic model
- does not have to be linear
- does have to be monotonic
- Is there no reversal of the trend for sleepiness after sleep deprivation??
- Incompatible with a pure homeostatic model! — can’t just be homeostatically regulated. There are cases of other things.
oleksenki study
Sleep deprivation studies with dolphins
studying sleep deprivation requires…
interventions - eg. applying something rather than taking something away
sleep terrors
Sleep/night terrors are episodes of sudden awakening full of extreme terror and panic associated with activation of the autonomic nervous system (Leung et al., 2020)
bipolar effect on sleep even after treatment
Those in a stable mood state may still show disrupted sleep
- Frequent interruptions/wakings
why may SWS take precedent over REM sleep?
REM sleep starting later on recovery night, SWS may be getting precedent because it is recovery sleep
what is zungunruhe and when does it occur?
zugunruhe (migratory restlessness; Figure 5.23), which is oriented in the compass direction toward which migration would occur in free-living birds (Kramer 1950). During expression of zugunruhe, brain regions involved in processing information relevant to migratory orientation reverse the timing of their spontaneous activation from day to night, indicating a broad reorganization of brain functions related to photoperiod
Is sleep duration the right measure of the extent of recovery??
(food example)
Example: if food intake is relating to maintaining energy balance, and someone is deprived of eating for 24 hours, do they then need to eat for 24 hours to restore energy homeostasis?
observational study: cold
- Probability of getting a cold for different sleep durations
- Less than 5 hours = 45% change getting cold
- Greater than 7 hours = 15% chance getting cold
Weight gain in response to sleep deprivation may also depend on…
the time at which sleep-restricted participants eat
Results from studies where people are selectively deprived of REM sleep show?
- Increased drive for REM sleep later in the night — could that be be:
- Explained by increase in circadian promotion of REM sleep later in the night?
- Or homeostatic pressure for REM sleep?
best for species to…
avoid activity at the “wrong” time of day
Actigraphy study with male and female adolescents, looking at insulin resistance in relation to their weekday sleep duration (axis)
X-axis = sleep durations split into quartiles from shortest to longest — 1 = shortest sleep duration, 4 = highest
Y-axis = insulin resistance
unihemispheric sleep seen in
cetaceans: dolphins, whales
chronic insomnia patients
- Underestimate their total sleep time
- Overestimate their latency to fall asleep
- Have more short arousals during the night than is typical
- Misperceived PSG-defined sleep periods as being awake
why do we see sleep waking more in childhood
We tend to see it more in childhood because there is a higher proportion of SWS in children, therefore higher likelihood that it would happen
spegiel et al flu results
- People were immunized for flu on day 4:
- Group 1: control
- Group 2: sleep restricted for 4h nightly for 6 days
–> Group 2: less increase in antibody levels
rats DOW what is the mechanism of physiological changes observed?
- Bacterial infections resulting from failure of the immune system?
- Metabolic changes that resulted in the infections?
bipolar disorder: Abnormalities in circadian organization may generate some symptoms
- Phase advance»_space; increased activity, reduced depressive symptoms
- Most people with bipolar disorder have habitual delayed chronotype (even during periods of euthymia)
Mechanism by which sleep affects the immune system
- Complex, findings inconsistent across studies
- Immune system includes many interacting components that are regulated by both endocrine and neural inputs
Symptoms triggered by ______ overlap those seen in depression
pro-inflammatory cytokines
several bird species show…
uni- and bihemispheric sleep
sleep dprivation…
increases sensitivty to pain
depression: Healthy controls mimic typical sleep pattern of major depression
SWS reductions
Decrease in positive mood
Increase in negative mood
(not in the clinical range)
Obstructive sleep apnea
cycles of stopping breathing for seconds or even minutes while asleep. Results in reductions in oxygen levels in the blood, followed by gasping intake of breath and arousal
brain can _____ the experience of pain
moderate, intensify or even create
Physiological/anatomical features example
e.g., metabolic rates, brain or body size
drive for REM pattern over the day
We see REM sleep continues to increase until noonish and then starts to decrease again — if you were permitted to nap between 6am-12am you would still have increases in REM sleep
losing sleep leads to…
an increasing motivation to fall asleep (despite strong motivations to stay awake!)
observational study: hep b
- Clinical protection against Hepatitis B after immunization
- People that sleep less than 6 hours 70% clinically protected
- People that sleep greater than 7 hours 95% clinically protected
metabolic rates are reduced…
during sleep, so smaller mammals can use longer sleep durations to reduce their overall energy costs
CBT for insomnia alone…
reduced depressive symptoms and reduced risk of new onset of depression by 50% over the following year in those with w/out depression at baseline
Glial cells in brain are known to generate metabolic heat in response to the neurotransmitter __________________ , levels of which are high during waking, but low in SWS and REM sleep. Glial heat could help preserve brain temperature and function.
norepinephrine
Is there a relationship between sleep and getting sick?
Yes!
oleksenki methods
dolphin was stimulated to wakefulness when one hemisphere showed EEG sleep signs (consistently same hemisphere)
predictive homeostasis?
motivates behaviour in order to avoid deficit situations
Sleep and anxiety and mood disorders
Many psychiatric conditions are characterized by unusually short, long, or disrupted sleep
Are sleep problems symptoms of psychiatric conditions or do sleep problems perpetuate illness?
after sleep deprivation…
there is a rebound increase in the duration of recovery sleep compared to baseline sleep durations, but it is not enough to make up for the hours of lost sleep time
sleep apnea is a major contributor to…
shortened sleep and sleep disruption
what do leukocytes produce
Produce cytokines (small regulatory proteins) that serve as important signals in the immune system
during sleep deprivation, people can show…
very brief sleep episodes (microsleeps) while awake
insomnia symptoms
- Difficulty initiating and maintaining sleep
- Early morning awakening
- Non-restorative sleep
- 3-4 times per week persisting for more than a month
variability in REM sleep examples…
Horses: ~0.5 hours (17%)
Possums: ~7 hours (50%)
circadian system of sleep functions…
independently of direct feedback from the processes it regulates (Process C)
roehrs et al study results
Results: pain tolerance at baseline was the same
Day 4: People with extended (Extra) time in bed could keep their finger on the hot stimulus for up to 2 seconds longer
More evidence that getting enough sleep decreases your sensitivity to pain
Reverse causality?
E.g., Only short sleep associated with later development of metabolic syndrome
Long sleep emerged in parallel to symptoms of the metabolic syndrome
variability in total sleep duration examples:
Elephants: ~2 hours
Armadillo: ~18 hours
metabolic rate =
the amount of energy expended while at rest in a neutrally temperate environment, and in a post-absorptive state
hypertension
(high blood pressure) – force of blood flowing through blood vessels/against walls of blood vessels
Sleep restriction studies where participants ate consistent, rigid diet
participants lost weight
- Spending more energy staying up, not matching that with food leads to weight gain
Symptoms triggered by pro-inflammatory cytokines overlap those seen in depression:
Lack of energy
Reduced activity
Negative mood state
Disrupted sleep
What is the relationship between altricial mammals and REM sleep?
strong positive correlation between how altricial neonates are and the amount of REM sleep shown in infancy. premature infants shown higher REM amounts than full term infants.
Unihemispheric sleep in other species
Observed in aquatic and semi-aquatic mammals
parasomnia treatment
Low-dose benzodiazepines (e.g., Lorazepam) or antidepressants (e.g., Trazodone)
Behavioural management
- Scheduled awakenings
- Positive bedtime routine
Appropriate interventions to manage psychosocial stressors
phylogeny example
(species relatedness) — eg. Humans and dogs not biologically related, but quite socially related. We may see some common behaviours due to social commonality (not sleep)
______ strongly predicts development of hypertension, independent of total sleep duration or other potential confounders
reduced SWS
cetacean sleep
- Shows only high- or medium-voltage EEG patterns (SWS)
- REM sleep absent or undetectable
humans are ____ same with ___
Humans are “middle-of-the-road” among mammals — same with moles (seems just to be a funny coincidence)
gardner, after sleep deprivation
~15 hours his first night
~10 and ~9 hours on second and third night
Independence of function due to smaller corpus callosum in cetaceans?
But absence of corpus callosum (surgery or developmentally) in people does not result in strongly asymmetrical sleep patterns
slow wave activity (SWA)
0.5-4.5 Hz
parsomnia
iundesirable physical or experiential events that accompany sleep
Total sleep time correlates _____ with both brain weight and body weight
negatively
sleep disturbances in dementia
nocturnal confusion - sundowning
-Reduced amounts of SWS
-Increasing disruption of sleep and daily rhythms as disease progresses
-Disturbed sleep often appears before cognitive symptoms
endotherms require…
high levels of energy expenditure to maintain body temp
avoid activity at wrong time of day examples
- Eg. Langer (monkeys) are active during the day, so they have a very well adapted visual system for daylight. They are diurnal
- Eg. Bats. Nocturnal, very well adapted to get food at night, very good sense of hearing and echolocation.
- If we forced a langer to be active at night, very good chance it would be at risk and not fair well. Vice versa for bats.
what do marine mammals rely on
- Rely on activity of large muscle groups as a major source of metabolic heat
- Unihemispheric sleep prevents total muscle atonia
Elevated glucose after 5 nights of 4 hours time in bed…
- After dinner glucose level goes up and is then maintained, stays elevated for people that get less sleep and overnight there is a quite different
- Sleep restriction four hours a night shows elevated glucose levels, body is having a harder time regulating glucose metabolism — could result in diabetes later on
Is sleep duration the right measure of the extent of recovery??
Hours of sleep do not appear to be the target of homeostatic regulation»_space; Sleep is a mechanism that permits homeostatic regulation of a physiological target
Ju et al. (2017)
Selectively disrupting SWA increased CSF Aβ levels
what is closely linked to disturbed sleep
chronic pain
Varga et al (2016)
Healthy older adults
Those with the most SWS had lowest levels of Aβ in the CSF
sleep deprviation effects on depression
-In depressed patients, sleep deprivation can improve mood and reduce other symptoms of depression
-Consistent findings that this works for some
-Overnight complete or partial sleep deprivation alleviates depressive symptoms in ~50% of depressed patients
-Mood and energy improvements can happen overnight!!
-Phenomenal because drug treatments can take days to –weeks to even work
monotreme REM sleep accompanied by
cortical slow waves (not activated pattern like other mammals)
SWA
you need a certain amount, can be attained through naps and sleep. just has to sum to relatively the same amount!
rem/body weight human relationship
Similar relationship exists in humans. Babies have shorter NREM-REM sleep cycle lengths than adults, consist with their smaller bodies and brains, and higher metabolic rates
Evidence that attempts to increase sleep duration result in improvement in insulin sensitivity (leproult)
Habitual short sleepers (mean 6.5hrs) increased weeknight sleep for 6-weeks
Those with the largest increases showed most improvement in insulin sensitivity
- A lot of things contribute to glucose regulation, everyone is going to have a different baseline for how much sleep their body needs.
Basic Rest Activity Cycle (BRAC) evidence?
not a lot of evidence to support
stressors?
environmental events that exceed an animal’s natural regulatory capacity”
- Especially events that are unpredictable and evoke physiological changes that are uncontrollable
what are luekocytes
white blood cells
methods of sleep deprivation?
voluntary (human)
small platform (flowerpot)
disk over water
motorized wheel/treadmill
gentle handing
human study weight gain sleep deprivation
Overweight participants in 20-week structured weight-loss program.
Those with later meal time (after 1500) lost body weight more slowly than those with earlier meal time (before 1500)
what could variability in sleep patterns be related to?
Physiological/anatomical features
Ecological niches
Phylogeny
Experimental studies have shown that reduced sleep over a few nights can produce…
measurable weight gain
sleep apnea diagnosis?
Not often diagnosed, or only after years of illness
bipolar disorder hypomanic episodes
- Sleep amounts reduced, activity levels and arousal increased
- Increased density of REM, reduced sleep efficiency
- More N1 sleep
reactive homeostasis?
respond to deficits once they have occurred
two participants (man and woman) that claimed to sleep very little
- Man slept 7.2 h
- Woman slept 6.9 h
- Both denied having slept at all during their night in the lab
sleep features
-Disrupted sleep, delayed sleep onset, reduced total sleep duration
-Reduced amount of REM sleep, N2 sleep, or SWS
People restricted to 4-6 hours of sleep for 5-7 days have not shown…
gradual reduction of homeostatic responses
sleep loss and pro inflammatory cytokines hypothetsis
Hypothesis that sleep loss»_space; release of pro-inflammatory cytokines»_space; contributes to depressive symptoms
Sleep deprivation consistently improves symptoms across different people with depression
-Recently diagnosed
-Years of recurrent depression
-Regardless of severity of baseline symptoms
-Regardless of ongoing (ineffective) antidepressant treatment
-Exposed to bright light or darkness during sleep deprivation
-Unipolar major depression
-Depressive phase of bipolar disorder
process S
the process of accumulating and satisfying the need for SWA
what is idiopathic insomnia
longstanding form that first develops in childhood
great frigate bird
- Non-stop flights for up to 10 days
- Greatly reduced total sleep time
- Increased asymmetry in sleep between hemispheres
Sleep and schizophrenia
Decreased numbers and density of sleep spindles
First-degree relatives show significantly reduced spindle amplitude compared to controls
insulin causes cells to ____ which reduces blood-sugar levels
take up glucose
during recovery sleep,
SWS increased substantially even though it was not reduced during sleep restriction
narcolepsy onset
Onset in adolescence or young adulthood (15-30 yers)
SWA is…
a reliable marker of sleep homeostasis and appears to be closer to the regulated target than duration of sleep.
sleep features in anxiety disorders
-Decreased total sleep time
-Increased sleep- onset latency
-More wake episodes interrupting sleep»_space; reduced sleep efficiency
sleep and weight correlation coefficient
~0.55
Functions of unihemispheric sleep in marine mammals
Permits sustained sleep while still showing necessary motor behaviours
Vigilance
Marine mammals expend a lot of energy to maintain homeostatically high body temperature relative to the water
what do benzos work on and what do they do
GABA is the primary inhibitory NT in the brain. Benzos are depressants that produce sedation and hypnosis, relieve anxiety and muscle spasms and reduce seizures.
motorized wheel/treadmill: deprivation/approach/controls
- ‘total’; short or long term
- active; continuous forced locomotion
- voluntary locomotion or free sleep
is studying sleep deprivation we have to think about…
is the act of preventing sleep causing something else (Eg. stress) and could that be having the effect
In habitual short and long sleepers (women), short sleepers have an increased risk of
diagnosis of pneumonia over 4-year period
STOP
> > Decrease in NREM sleep, increased waking, more transitions between NREM and REM sleep
monotonic meaning
no reversal in the increasing trend
relative to body size - metabolic rate
Large mammals (relative to body size) has a small amount of skin exposed — this leads to a lower metabolic rate.
Smaller mammals have a greater amount of skin exposed. There ratio of skin to body size means they need to use a lot of energy during the day to keep their body temp above the external temp.
dementia study(?)
Accumulation of neuronal plaques containing peptide amyloid beta (Aβ)
Intracellular aggregation of tangles containing tau protein
amount of SWA produced during a daytime nap…
reduces the amount shown during the next night’s sleep
slow wave oscillations
0.5-1 Hz, very high amplitudes >140 V
As deprivation of SWA lengthens during waking…
the pressure to express it increases, generating SWA reduces that pressure
Human participants asked to sleep for 3 successive nights for 8 h, 12, h, and 8 h respectively: REM findings
REM sleep increased by ~90%!
speigel et al study topic
flu
Studies of chronic sleep deprivation in rodents suggest homeostatic regulation of sleep may have limits , example
In response to extreme challenges, homeostasis may give way to allostasis
Complex process in regulation of ___ sleep, in relationship with ___
REM, SWS
ecological niches example
eg. diet or habitat
insomnia is
The most commonly reported sleep disorders
proportion of REM sleep…
increases over the night
____ of people with OSA showed non-dipping pattern
60%
Reduced nighttime melatonin contributes to
elevated nocturnal blood pressure
anxiety disorders
E.g., GAD, panic disorder, PTSD
Anxiety is a prominent feature of major depression
behavioural criteria for sleep
- sleep site
- immobile
- elevated threshold for arousal
- moderate stimuli leading to more/less rapid reversal of state
- deprivation of sleep leading to rebound in sleep duration
does everyone show nocturnal dipping?
no, not everyone
Short-term homeostasis of REM sleep
- REM sleep and NREM sleep are each regulated by independent homeostatic mechanisms within a sleep period
are there different treatments for daytime sleepiness and cataplexy
yes!
idiopathic insomnia symptoms
- No specific factors trigger onset
- Persistent, without periods of remission
- Doctors dont know the cause
