test 2 Flashcards
careful study of circadian rhythms in people requires…
isolate from zeitgebers
constant environments for studying sleeo?
deep underground caves
laboratories
- constant temps and total darkness
who spent time in kentuckys mammoth cave and for how long
nathaniel kleitman and bruce richardson, 32 days
who spent a lot of time in underground caves
michel siffre spent time in caves and underground glaciers in multiple experiments — he was alone in the original studies and calling up to a research team to report
who used a WWII bunker
aschoff and Wever used an underground bunker from WWII modified into a well-equipped and isolated lab for studying individuals living in time-free environments
did lots of people ask to end time in the sleep cave early?
ery few participants found the isolation to be disturbing or asked to be released early
what did aschoff and wever find - interesting finding
Aschoff and Wever reported that some participants developed a strong interest in guessing the time in the external world
- Guessing research assistant’s schedules relative to external time (day crew or night crew)
- Studies in hospitals or universities, participants could feel vibrations from elevator shafts, thus able to guess when the workday started and ended
- Experiments had to work on irregularly staggering schedules to conceal information about the time of day
Without cues, meal patterns, body temperature, and sleep-wake cycles free-run with periods…
different than 24 hours
Spontaneous desynchronization?
different rhythms with different periods
Spontaneous desynchronization examples
Eg. Some participants showed sleep-wake cycles much shorter or longer than 24 hours, while body temperature rhythms free-ran with periods close to 24 hours
spontaneous desynch example siffre
Michel Siffre reported sleep-wake cycle of 50 hours in some cases, but body temperature stayed in circadian range
- This is a bit extreme, his probably ran a little long naturally
- Did cognitive testing: took him a long time to count to three for example, his personal perception of time was longer
those with very long sleep wake cycles
- Average hourly activity levels were lower
- Ate meals at longer intervals
- Estimated an hour as being longer
- Had lower average body temperature
those with very short sleep-wake cycles
- Average hourly activity levels were higher
- Ate meals at shorter intervals
- Estimated an hour as being shorter
- Had higher average body temperature
people with very long and short sleep wake cycles found to…
be active for the same total time at the end
in controlled environments with no external time cues what can still be an issue?
some variables can still affect measurement of rhythms
the circadian rhythm of body temperature responds to a number of masking effects
Large meals increase sleepiness
Exercise increases body temperature
Body temperature decreases during sleep
Even if researchers attempt to limit external variables (eg. Alarm clock), there are still…
many effects that can occur even through participants self-selected patterns
what things can researchers not control in measuring sleep
Body temperature, some hormones, change depending on whether a person is laying down, standing or sitting
Campbell and Broughton study
Purpose:
clarify the temporal relationship between the nightly decline in body temperature and the timing of the onset of nocturnal sleep
Campbell and Broughton whole study
???
Campbell and Broughton correlation
Significant positive correlation between the amount of wakefulness within the first hour after initial sleep onset and MROD relative to both bedtime and sleep onset
- That is, the closer MROD occurred to either bedtime or sleep onset, the less wakefulness there was within the first hour after sleep onset
Campbell and Broughton findings
- Findings indicate that the process of sleep initiation is most likely to occur when the body temperature is declining at its maximum rate and is most successfully accomplished at this phase of the temperature cycle
- If you were too warm when trying to go to bed (artificially raising body temp), it can be hard to fall asleep
- Feet should be warm
internal masking
changes in the value of a target measure (Eg. Body temperature) that result from the participant’s own behaviour rather than from either an external disturbance or the dictates of the circadian clock
internal masking examples
Doing exercise, eating a big meal, etc. could change one of their cycles
how do researchers get around internal masking in lab studies
constant routine
forcred desynchronization
constant routine
participants maintain an unchanging posture (eg. Semi-recumbent), remains awake, consumes identical, isocaloric mini-meals at frequent internals for 36-48 hours. These extreme measures may affect circadian rhythms measures!
forced desynchonrization
create unusual sleep-wake patterns so that sleep occurs at many different phase of a participant’s circadian cycles. Allows researchers to measure the impact of circadian systems on many features of sleep. Eg. How do the different phases of the body temperature rhythm affect REM sleep?
impacts of lab environment
- Laboratory studies permit precise analysis of the effects of experimental manipulations, but constrain behaviour in unusual ways
- Many variables not included in lab studies may affect daily rhythms
predation pressure and resource competition
- Two spices of spiny mice with overlapping habitats in Israel — less aggressive species less active at night because they don’t want to interact
- Norway rat groups in semi-natural enclosures — social dominance and competition determined the daily timing of feeding by non-dominant individual
- Two closely related sloth species — sleep timing differed with exposed to different predation pressures in their natural habitat, because of unsafe during sleep
what do field studies help us to understand
help us understand how circadian rhythms respond to complex variables in real-world environments
there is ____ variability in sleep characteristics across individuals of the stage age and same species
large
newborns show ____ circadian modulation of their sleep-wake cycle
little
polyphasic pattern of newborns
multiple sleep-wake cycles throughout the day (relatively brief sleep episodes occurring throughout the day and night)
Patterns of sleep-wake cycle change dramatically in the _____
first 6 months of life
Generally diurnal sleep pattern develops by
12-14 weeks of age (~3-4 months)
by 6 months, over 50% of parents report
infants sleeping regularly between 22:00-6:00 (10pm-6am) roughly 8 hours overnight, then lots of naps during the day
why do infants develop a regular sleeping pattern
Not really clear if this is excuse they become entrained to environmental cues or social cues, very likely a combination
Infant is starting to go to sleep and wake up at the same time everyday (approx. 7pm to 7am) starting at
18-19 weeks.
seeing a slight _____ in sleep time and adoption of a regular sleep cycle as infants age
derease
Results could suggest that the internal circadian clock for sleep-wake cycle matures….
very early in development and is later entrained to the day-night cycle
sex based differences in baby sleep entrainment
In a second study of a male from bright to 6 months, entrainment appeared much earlier: ~ day 30 vs. ~day 112 (for female)
hard to seperate maturation of circadian system from ___ and ____
parental/social cues
exposure to life
two infant sleep stages?
active sleep
quiet sleep
active sleep (as)…
resembles REM sleep
quiet sleep (qs)…
resembles non-REM sleep
full term infant sleep amount
Sleeps ~16-18h daily broken into 2-4h sleep periods
full term infant rem sleep amount
REM sleep is ~50% (8-9h) and alternates with NREM sleep in ~50-60min cycles
- A lot compared to adults, shorter cycles that ours
when does rem ocur for newborns
Newborns fall directly into REM sleep at sleep ones
at 3 months of age
more NREM sleep, and REM sleep occurs later in each sleep episode
at 6 months of age
typical adult patterns established with NREM sleep regularly occurring at sleep onset, REM sleep now ~25% of sleep cycle
altricial
an animal hatched or born helpless and requiring significant parental care
precocial
capable of moving around on its own soon after hatchin
human auditory system
Humans have a relatively developed auditory system in the womb, visual system is relatively well developed. Other apes can hold onto their parents, however, we cannot.
altricial mammals have an…
immature sleep-wake pattern
precocial mammals show…
adult-like EEG sleep patterns by 1-week after birth
- But show higher levels of REM sleep prenatally (when their sleep anatomically more closely resembles altricial mammals)
how could u measure sleep in childhood
- population based surveys asking about average sleep duration
- sleep studies with children
population based surveys asking about average sleep duration issues
- parents are not always good reporters of their Childs sleep (might not be super accurate)
- Average sleep duration may be affected by societal and cultural norms
- Average sleep duration is not necessarily how much sleep children need
sleep studies with children methods
- Polysomnography in the lab or at home
- Parental reports
- Self-report (older children)
- Sleep diaries
- Actigraphy
Physiological measures and parental reports do not always converge — what is more accurate?
physiological measures are typically more accurate
~1 year of age amount of sleep?
~11h daily
> 1 year of age, total number of hours of sleep
declines reaching 9-9.5 h by age 5
what happens w total REM duration during sleep over 1 year of age
Total duration of REM sleep gets a little higher because there is a total decrease in sleep, REM becomes a higher proportion of sleep increases because you begin sleeping less in total
when are total daytime naps lost in north america?
by 5 years
evidence suggests that midday naps may be
Total duration of REM sleep gets a little higher because there is a total decrease in sleep, REM becomes a higher proportion of sleep increases because you begin sleeping less in total
- apes nap a lot
Study of 3 different cohorts in Switzerland (1974, 1979, 1986) results
- Seeing a gradual decrease in the total duration of sleep
- That observed decrease in sleep over time is most pronounced in younger ages (about an hour difference in total — that is a big chunk of sleep)
- Decreased sleep large because of progressively later sleep onset times — these are believed to be cultural differences
recommendations for sleep duration: infants 4-12 months
12-16h per 24h including naps
recommendations for sleep duration: children 1-2 yrs
11-14h per 24h including naps
recommendations for sleep duration: 3-5 yrs
10-13h per 24h including naps
recommendations for sleep duration: children 6-12 yrs
9-12h per 24h
recommendations for sleep duration: teenagers 13-18 yrs
8-10h per 24h
sleep in adolescence findings
Longitudinal study found steep decline in EEG delta power density during NREM sleep from ages 12-14 years — less delta waves, then continues to decreases
when did decline in delta power density occur for adolescents
began 1 year earlier in girls than in boys (drops around 11 in females, 12 in males)
similar sleep decline in ______ as we age
cortical theta power
campbell and feinberg propose cortical theta power decrease might be linked to decline in
Cortical synaptic connectivity
Grey matter volume
what happens during puberty and its effect
decline in cortical synaptic connectivity and grey matter volume occurs during puberty, resulting in reduced local neural synchrony — fewer connections in the same area because there is an overall decrease in connections being made after puberty
what does reduce local neural synchrony result in
more desynchronization
from birth to 5 years old, huge amount of
synpatogenesis — forming a lot of new connections when really young
between 10-15 (puberty), huge amount of
synaptic pruning, use it or lose it concept
the degree of local synchrony in neural activity contributes to…
the amplitude of EEG fluctuations
a decline in local synchrony of neural activity would result in a
educe the amplitude of EEG voltage changes, leading to reduction of cortical EEG power in theta and delta ranges (waking and sleep)
What accounts for the increase in the ratio of white to grey matter seen in adolescent girls?
increased myelination (not seen in boys they have testosterone-dependent increases in axon diameter)
adolescents show a ______ and gradual ____ in total time slept
delay in timing of sleep onset, redution
what has delay in sleep onset and reduction of total time slept in adolescents been attributed to?
- Change in the underlying period of the circadian clock regulating sleep-wake timing
- A change in sensitivity to the phase-shifting effects of light — eg. If you are exposed to light in the evening you just end up staying up later
- Fixed waking times determined by school schedules — regardless of when you went to bed and wanted to wake up. Leads to quite negative effects
- Regardless of changes in underlying changes in sleep-wake, school doesn’t take that into account
what reflect different preference for sleeping/waking time?
Remember early risers (phase lead) and night owls (phase leg) — different preferences for timing of sleep and waking represent different chronotypes (reflect differences in the phase of entrainment of the circadian clock to the 24h day)
what are early risers
phase lead
what are night owls
phase lag
roenneberg MCQ study participants
~25000 participants from Germany and Switzerland, had a bunch of ages measured on free days
roenneberg results
From a young age people tend to have an early chronotype, as you age until about the point of 20 that slowly gets later. After about 20, we see it starts to shift towards an early chronotype again
what are free days
‘free days’ — days when there was nothing to do, eg. No social obligations in the morning. Trying to get a measure of common chronotypes regardless of social pressure
female findings for free day patterns
Females start to shift earlier in development (19 rather than 20/21) — see that they converge in 40s to 50s
male findings for free day patterns
Males tend to develop a much more extreme late chronotype — prefer to stay up a lot later and wake a lot later
evidence that ____ act on the period of the circadian clock
sex hormones
delaying of circadian clock tendency begins at…
Delaying tendency begins at puberty, with differences parallel to differences in timing of puberty
what is true about age of reversal from delayed to advanced phase preference
differs in young men and women
there is a sex difference difference in ____ throughout ____
phase preference, young adulthood
when is the phase preference sex differene lost
Difference lost around menopause — as hormones kind of even out between sexes, women develop more testosterone. This is where the timing becomes much more similar
evidence that young adult men with higher levels of testosterone were…
positively correlated with more extreme evening chronotype scores
there is some ____ basis for sleep and wakening time preferences
genetic basis
genetic cause: familiar advanced sleep phase syndrome
mutation in CASEIN KINASE I that regulates expression of criciadna clock gene (PER2)
genetic cause: delayed sleep phase syndrome
polymorphisms in the circadian clock genes PER3, CLOCK and CRY1
triggers for typical sleep phase
close to when dark outside
triggers for delayed sleep phase
doesn’t go asleep until its been dark for a while, sleeping into daylight
triggers for advanced sleep phase
might wake up when still dark outside
delayed/advance sleep phase
actual conditions, can really impact peoples lives
lund american uni students: how many get less than 6.5h of sleep
25%
lund american uni students: how many missed an entire night of sleep in the last month
20%
lund american uni students: how many stayed up until 3am once per week
35%
lund american uni students: how many fall asleep in class once per week
15%
school average start times in the US
7:30-8:30am
students with school start times before 8:30 had…
shorter sleep durations than those with later start times
racidalized people and lower SES groups were…
less likely than others to get a least 7h of sleep nightly
school start times and social jet lag
Average duration of sleep is much higher (an hour more) on weekends and vacation (free) compared to school nights
those getting less sleep report ___ grades, same with really high amount of sleep. best grades with ___ amount of sleep
slightly lower, 8/9hr best
people with less sleep duration =
more depressed moods, more risk-taking behaviour, engage in more self-harming behaviour, increased risk of automobile accidents compared to those with later start times
social jetlag
mismatch between external societal demands and internal temporal physiology
how is social jetlag measured
as the difference between the time of the mid-sleep phase on free days to the mid-sleep phase on school/work days
social jetlag has been linked to
- Poorer academic performance in university students
- Inadequate control of glucose levels in adults with T1D
- Increased cardiovascular risk in adult shift workers
- High body-mass index in preteen girls
school performance in adolescents:
- Those with morning preference performed better during tests in the morning
- Those with evening preference performed better later in the day, independently of preceding sleep durations
school performance in secondary school students:
- Those with evening chronotypes performed poorly on test in the morning relative to those with morning chronotypes
- Performance was similar on afternoon tests, regardless of chronotype
haraszti social jetlag and academic perforamnce results:
- Seeing correlation between high SJL and lower grades
- Appears SJL in the term is not good (SJL = free days - week days of midpoint sleep time) — catching up on the weekend doesn’t seem to do as much as you’d want it to
delayed sleep phase syndrome
Extreme form of a delayed sleep phase preference
delayed sleep phase syndrome actigraphy results
we see that the chronotype is so delayed that we can see that sleep onset is around 5-6am. Wake times are around noon, however, quite variable.
delayed sleep phase syndrome related to
having a longer period circadian rhythm
comparing delayed sleep phase syndrome people to regular people
- resting and core temperature phases are significantly longer in those with this syndrome
- regular people have rhythms around 24 hours
one of the causes of delayed sleep phase syndrome is believed to be
increased sensitivity to the delaying effects of light in the evening
increased sensitivity to the delaying effects of light in the evening causes
- Greater light suppression of melatonin levels
- Larger phase shifts of the melatonin rhythm
what happens if even longer-period circadian rhythm fails to entrain at all
development of non-24 hour sleep-wake disorder (N24SWD) with free-running sleep-wake rhythms in the presence of day hour day-night cues
what happens with N24SWD
- Rhythms constantly move around
- Their melatonin and core temperatures are even longer than those with DSWPD and significantly different from controls
best way to diagnose DSPS
- to observe the persistence of the extreme preference for delayed sleep onset despite best efforts to achieve an earlier bedtime
- strategies could include: ideal sleep environment, really limit exposure to light in evenings, create consistent schedule throughout the week
- assess sleep timing and quality on free days with no externally set wake time
- If all of this is the case and they still go to bed really late, the likely have DSPS
in diagnosing DSPS, need to rule out sleep onset insomnia which is
inability to fall asleep at a person’s desired bedtime
- Occurs due to anxiety related to social or academic issues
treatment for DSPS
- Rigid sleep scheduling
- Avoiding evening light exposure
- Using melatonin in the evening
- Strong light exposure in the morning
- Chronotherapy:
what does strong light exposure in the morning work for
These treatments only really work for moderate cases and can advance the sleep phase by ~1 hour
chronotherapy
delaying sleep phase 2-3 hour daily around the clock until reaching a more suitable sleep time
- This won’t work for some people and then they end up with an uncontrolled free running rhythm, could be even worse than DSPS
DSPS, there could be
genetic component, some people just may not choose to treat it and build their life around it
with aging, sleep shifts to a
more preferred early chronotype
in aging there is
Less slow wave sleep (3), longer latency to fall asleep, more waking in the night
difference in sleep throughout aging could be due to the following sleep disorders…
- Sleep apnea
- Periodic limb movement
- Restless leg syndrome
differences in sleep throughout aging could be due to the following conditions…
- Joint inflammation/pain
- Frequent urination
- Mood disorders
ohayon meta-analysis found the following changes in sleep from adolesence through adulthood and into old age:
- Increased latency to fall asleep
- Increased percentage of WASO, decrease in total sleep time
- Increased percentage of N1 and N2 sleep
- Decreasing percentage of REM sleep, small decrease in REM sleep latency
- Decreased percentage of N3 (and Slow wave activity)
females have more stage ___ sleep than males
3/4
males have more stage ___, way less ____
more N1, way less N3
much more pronounced sleep changes in male sleep ___ than females
architecture
what is bizzare about the pronounced sleep changes in males vs. females?
Despite those objective differences, that is not matched by subjective reports between males and females
women report a lot higher ____ than men
incidence of insomnia
chronic insomnia
complaints of chronic (>3 months), difficulty initiating or maintaining sleep, early awakening, interrupted or non-restorative sleep, resulting in clinically significant distress or impairment in social, occupational, educational, academic, behavioural or other important areas of functioning
women consistently report more….
significant disturbances
role of menopause
Peri- and postmenopausal women report more sleep problems than pre-menopausal women, same problems with women that have had hysterectomies
Might not just be due to the aging process
some studies report… (in relation to menopause)
no objective evidence using PSG of disrupted sleep during and after menopause
some studies have found… (after menopause)
- Strong objective evidence for a temporal relationship between hot flashes and awakenings
- More total wake time, and reduced sleep efficiency
- Increased incidence of sleep apnea symptoms
relationship between… (pre and post menopausal women)
Relationship between increased high frequency (beta-band) EEG activity during NREM and REM sleep in post-menopausal women compared to pre or early menopausal women
change between pre/post menopausal behaviour
- Poor perception of sleep
- Increased probability of waking
- *beta bands occurs during N1/being wake
what is follicle-stimulating hormone (FSH)
often a measure of what degree of menopause they have gone through
after menopause women showed…
increased hot flashes, more N1 sleep, less N2 sleep, more awakenings during the night, more signs of sleep-disordered breathing, shorter latencies to sleep onset and increased N3 sleep
what do sleep changes appear to be related to
aging, rather than extent of menopausal transition (indexed by FSH levels)
longitudinal menopause study caveat
- 21 participants were excluded because they started hormone replacement therapy (HRT)
- Those with most severe menopause-associated symptoms would be most likely to seek out HRT
- Therefore, those most affected my menopause were not represented in the study
older women have…
objectively better sleep quality (more N3 and less N1 sleep) than older men, but report more sleep disruption
what does N3 delta wave activity reflect
homeostatic sleep regulation and recuperative functions of sleep — N3 is the restorative phase of sleep, been associated with things like tissue repair, growth, cell regeneration — your body is fully relaxed in N3
REM delta power is…
not relevant to recuperation — really want to see delta waves in stage 3 of sleep
analysis showed that older men had a higher ratio of…
NREM to REM sleep delta activity compared to older women
men have been suggested to have…
better homeostatic regulation of NREM delta power (in N3, important part) even though their raw NREM delta-band activity was lower than in women
- Getting less but maybe much more efficient
women may be…
satisfying their homeostatic sleep needs less effectively than older men
- Men getting more of the restorative properties in less time, could explain the differences
skull
women have a thicker skull than men!
seidler: seasonality of human sleep aim
o determine objective sleep duration and architecture over 1 year in a large group of patients attending a neurologic/psychiatric sleep laboratory
seidler diagnoses (most to least prevalent)
insomnia, depression, sleep-related breathing, periodic limb movement restless leg, REM
seidler medication (most to least prevalent)
none, other meds, antihypertensive, thyroid, beta blockers, melatonin
what was seidler standard protocol
- Conducted PSG with patients for 3 nights: adaptation, diagnosis/data, treatment evaluation
- Standard protocol encourages patients to sleep during their preferred time and to sleep in. After the EEG- setup, “lights-out” is performed at a time individually determined by the preference of the patient.
seidler results
- Data from our study obtained from a heterogeneous patient group with sleep-related disorders show a significant variation of REM-minutes and-percentage of TST, with more REM-sleep during winter and less REM-sleep during summer
- Our findings suggest that improvements can be made by accounting for the increased sleep need in winter, by going to bed earlier. Furthermore, the current twice-annual turning of the clock may facilitate adjustments to seasonal changes in human physiology underlying the findings we report here.
age related changes in EEG features
- women have thicker skul than men
- Reduced cortical thickness, general loss of neuron numbers during aging
what does reduced cortical thickness and loss of neurons result in
- Fewer synchronized neurons contributing to EEG signal
- Electrodes further from the cortex
all EEG waves (Regardless) of amplitude in men?
similar SWS percentage as in younger adults
was there a sex density difference in density of SWS from young and older adults?
no sex difference
young and old decided age ranges?
young = 20-30
older = 50-70
amplitude of SWS finding in women
higher in women
what happened to number of SWS in older groups of both sexes
robust decline
wha could difference between male and female SWS be attributed to?
differences in chronological age versus physiological age
are there actually functional implications for differences in SWS as we age?
- Reduced EEG delta and theta power in older people correlated with reduced benefits of overnight sleep for memory performance – but not consistently!!
- Poor memory performance associated with prefrontal cortical atrophy; mediated by reductions in SWA during N3 sleep
- Performance on executive tasks positively correlated with prefrontal EEG power in the slow delta range (0.5-1.0 Hz, slow oscillations) during first N3 period / reduced prefrontal EEG power in this band during sleep associated with worse executive performance
ideally, studies of age related changes in sleep would be…
longitudinal
most studies of age-related changes in sleep are
cross sectional
cross sectional studies of sleep cannot…
demonstrate whether differences in sleep variables results from effects of aging on sleep-regulatory mechanisms
what does light have an effect n…
Effect of different light intensity exposure on melatonin suppression and phase delay
challenge in studying aging effects on sleep and circadian mechanisms?
- Older participants have many more life experiences that can affect sleep and circadian rhythms
- We cannot equate such life experiences
- Survivor effects: sample of any older participants is drawn from a pool of survivors of a larger age cohort that inevitably got smaller with the passage of time
- Better quality sleep and preserved daily rhythms are correlated with healthier aging and longer survival
People who live into their 80s are likely to have more of the - Those who participate in research studies are generally healthier
- Older participants differ more from the population they represent than younger participants
- When considering exclusion criteria for a study, different conditions occur with different frequencies in different age groups. Young people are excluded from studies for different reasons than older people.
can we equate life experiences?
Can use statistical methods to try to exclude variables with potential influences on sleep, but those variables can be difficult to identify
impact of survivor effects?
- Younger participants in a study will be more diverse than older participants with respect to factors (e.g., genetics) that influence longevity
- All of the older population, but only half of the younger population, will have characteristics that permit them to survive into their 80s
impact of better quality of sleep with healthier aging and longer survival
- people who live into their 80s are likely to have more of the characteristics that preserve sleep and circadian rhythm quality than others in their full birth cohort
- Those in their 20s would be a mixed group
considering old vs. young exclusion criteria for a study
- When considering exclusion criteria for a study, different conditions occur with different frequencies in different age groups. Young people are excluded from studies for different reasons than older people.
- “older subjects were excluded primarily for medical problems whereas younger subjects were excluded for personality disorders, substance abuse, obesity, and family history of depression”
20th century industrialized sleep conditions include
- individual sleeping space
- Heavily padded sleep surface
- Complete darkness or very low light intensity
- Physical barriers that reduce environmental noise
- Regulatory systems for stable room temperature
- A single, continuous nocturnal sleep opportunity
siestas are considered normal in…
many places (eg. Some African, asian, and mediterranean cultures, and those in the west influenced by them)
siestas are common in places that are
really hot!
siestas are considered rare and unusual in…
in other places (eg. Some asian countries, northern Europe and north America)
midday naps are common in…
traditional societies! and a lot of animal species (eg. kangaroos)
study of greek adolescents (14-18) napping?
- Nearly half reported regular siestas
- Equal proportion reported occasional siestas
- Median duration of 2h (range: 0.5 to 4.5 hours)
- Those with regular siestas less likely to complain of sleepiness
study of 500,000 people in china, how many report daytime napping
20%
china study, of those that report napping they have…
significantly lower risk of reporting insomnia symptoms than those who did not nap
*could just be that these people just sleep better, independent of napping
naps are thought to
increase productivity, being implemented by businesses, in airports, libraries
differences in nap and sleep timing across cultures
- Parents across 17 countries report that their children take similar length naps
- Parents in some asian countries report later bedtimes, but also more commonly, daytime naps than Western countries
nap discrepancy by age 5 in asian vs. western countries
By age 5, 60.7% of parents in Asian countries report their children taking naps, 6.8% in Western countries
impact of ramadan
Delayed sleep onset, reduced total sleep time
Increase tendency to sleep during the day
timing of major meals in the mediterranean
Largest meal eaten in early afternoon
Lighter late-night meal
average sleep duration across the world
~7.5h
range of average sleep time
6.9h in Japan to 13.4h in Portugal
regular napping japan vs. brazil
12% of Japanese respondents, 42.4% Brazilian respondents
poor sleep, insomnia china vs. south africa
6.2% of respondents in China, 24.5% South African respondents
australian adolescents slept ___ on school nights compared to american adolescents
~47 minutes longer
in ethnically homogenous samples within single nations: african american
hihger levels of psychosocial stress associated with more reports of poor quality, short sleep
in ethnically homogenous samples within single nations: longitudinal study of white children in the UK
Sleep problems increased as a function of reduced family income, lower maternal education achievement, and maternal anxiety and depression
in ethnically homogenous samples within single nations: china
insomnia symptoms associated with lower socioeconomic status, living alone, or a history of health problems
hale: sleep in middle-aged women - immigrant report
- Immigrant women reported fewer sleep complaints than those native to the USA
- Immigrant women reported fewer sleep complaints than those from same ethnic background but born in the USA
hale: more-established immigrant reports
Those more-established immigrants most strongly acculturated to English language usage showed largest increase in sleep complaints
hale: more-established immigrant theories
Could be due to adopting more American lifestyle, poorer diet, less exercise, more physical/social stressors, work ethic, developing more American/English terms about describing sleep — tendency to boast about not getting enough sleep is a north American thing
worthman and melby review of pre-industrial sleep methods
- Used self-reports and observations by anthropologists
- Mention of sleep was often incidental — happened to talk about sleep, but not reporting on sleep specifically
worthman and melby features of sleep that tend to vary among cultures include
- Where individuals sleep
- What structures they sleep in (if any)
- Who sleeps together or separately
- How sleep patterns change with age, social status, or current events
in traditional societies…
people are rarely physically isolated from others when sleeping
traditional society features of sleep
- Either sharing a bed or a sleeping space — one big room where everyone sleeps
- Not isolated from external stimuli — anything involved with having people in the same room; social activities, eating, sex, animals, babies, etc.
Sleeping arrangements within a society/group of people depend on a number of factors:
- Wealth
- Social status
- Sex
- Age
- Nighttime temperatures
- Nocturnal predators
- Parasites
- Disease
- Protection from other groups
- Witches or nocturnal spirits
sleeping arrangment indigenous australians
Indigenous in Australia — single men or families sleep in rows with the most capable in terms of defending everyone, sleeping on the outside. Determined by age and social status.
many societies sleep with…
other species nearby! or by a fire
implications of sleeping near a fire
- Sleeping around a fire provides warmth and defense, but fire also carries a number of dangers
- Must be maintained and contained by someone throughout the night
- Scares off animals, however, can attract a lot of things — like other people
- Fires can spread, need to be careful
- While the smoke prevents bugs, it also worsens your breathing environment
without schedule work hours…
sleep times are much more flexible
work and rest periodically
parents may not set sleeping time for children
daytime naps are common especailly after
extended wakefulness
sleep loss may be used to
encourage a dissociative state and as a test of endurance
in some cultures, people may engage in…
check-out sleep” during boring social interactions
When having a conservation with something and is bored, just go to sleep
history of nocturnal illumination
- Our visual system is strongly adapted to the daylight
- Humans’ evolutionary control over light gradually developed over time
- Fires from wood, coal, oil etc.»_space; candles, kerosene lamps»_space; electric power
- Commercially viable electric light bulb»_space; electric grids for power distribution allowed an extension of the personal “day”
- Factories lighting and electrically powered machines (not steam) allowed for continuous work
strong correlation between
satellite-measured, local light intensity and reported sleep problems among inhabitants
higher light intensity linked to
shorter sleep, delayed sleep onsets, earlier awakening, more dissatisfaction with sleep quality
controlling for population density…
did not eliminate the link between brightnights and delayed/problematic sleep
male birds living near artificial light sources showed…
earlier signing in the morning and had more mating success
female birds living near artificial light sources…
laid eggs earlier in the year than did those in similar habitats without artificial illumination
do people show photoperiodic responses (eg. seasonal changes in sleep)?
- Had people spend 8h versus 14 h in darkness over 4-week period
- During long nights, people extended their sleep time (7.6 h to 10.6 h)
- Divided their sleep in to early and late bouts with intervening awake period
- Showed less fatigue, better moods, and more energy in 14 h condition
- Duration of active secretion of melatonin lengthened (10.3 h to 11.9 h)
Did our improved control of lighting change the duration and pattern of sleep, and its linked physiological functions from pre-industrial to industrial societies?
??? should be in chapter 4 text
how do we study sleep in pre-industrial era ancestors?
- Examine written records
- Anthropological reports
- Extrapolating results from lab studies that mimic long nights etc.
studying people that choose to live without electricity/live in traditional societies example
- german TV show participatnts
german tv show participants finding
- Studied people before the show, during and after — they were there for 8 weeks total in Germany
- All subjects were quite variable in how much time they spent in bed before the study, they all increased their estimated time in bed during the experiment and then when they went home, it went down again (but not as low as before). Same pattern with actual sleep time.
- Shows that time without electricity led to more sleep
- All got a phase advance during the experiment (going to bed earlier). During the experiment they were also getting up a little earlier.
studies of people living in traditional societies without access to electricity - sleep variables?
- some studies reported segmented sleep patterns, others did not
- No naps, occasional naps, frequent naps
- Long times in bed
- Relatively similar sleep durations
- Fairly high levels of WASO (wake after sleep onset)
- Impact of light exposure was inconsistent among studies
how was sleep studied in people currently in traditional societies
Actigraphy, portable PSG, questionnaires
traditional society and sleep variables other findings
- High humidity and high levels of noise were associated with increased WASO
- High temperature increased sleep duration
- In general, because it takes energy to do things.
- High temperature early in the evening inhibited sleep»_space; more sleeping in cooler second half of the night
- Humidity and temperature really seemed to effect sleep. Really high temperatures in the evening inhibited sleep.
Studies with comparisons between related groups living near one another – one group with access to electricity, the other without (or very little) electricity: argentina
- Those with electricity slept 0.75-1.0 h less than those without electricity
- In argentina those who had access to electricity were sleeping up to an hour less than those without
Studies with comparisons between related groups living near one another – one group with access to electricity, the other without (or very little) electricity: vanuatu
- Similar to Argentina results
Studies with comparisons between related groups living near one another – one group with access to electricity, the other without (or very little) electricity: brazil
- They’d be transported from their villages during the week to the area where they would be working, sometimes wouldn’t have access to electricity
- Those who had access to electricity on both work days and not — going to bed later than those without. Same relationship with melatonin rise. If they have access to electricity it starts later in the night.
What do all of these studies of traditional soceities tell us about sleep?
- Lots of variability!
- Some support for the impact of electric lighting
- Factors other than light (humidity, noise, temperature) affect timing and duration of sleep
- There was probably never a single way of sleeping. Rather, many specific adaptations to local environmental conditions that varied across groups, geography, and time.
- In some cases electricity affected sleep, in others not
What effect has recent technological developments had on sleep? (Talking about phones, computers,): Bin?
Sleep durations increased in some countries and decreased in others–no universal trend across countries
What effect has recent technological developments had on sleep? (Talking about phones, computers): ford (american)
Up to 2004 = Weak trend towards shorter sleep and increased in percentage of people <6 h of sleep
What effect has recent technological developments had on sleep? (Talking about phones, computers): sheehan (american)
No increase in reported short sleep
2013-2017 = significant trend toward more reports of short sleep
Other studies conducted in Canada and USA reported minimal changes from 1980s onward reported…
- little change or slight increase in sleep duration for some subgroups of adults — were not seeing huge effects in technology on sleep
- Racialized groups and those already at high risk for short sleep appear to further reduce sleep durations
results for children and adolescents about sleep duration throughout time are…
more consistent
children: strong association between…
use of media devices near bedtime and shorter sleep, poorer sleep quality, and increased daytime sleepiness
american adolescents report an…
increase in short sleep durations from 2009-2015, associated with increased use of new media
what can electronics do?
Use of electronics that emit light in the blue part of the spectrum can delay sleep — leads to suppression of melatonin and phase delay in staying up to look at phone
blue light electronics study:
- Participants wore glasses that blocked blue-light wavelengths
- Used social media for 30min before sleep
- No effect on arousal levels or subsequent sleep quality
- Not the social media content itself…. — what you look at on social media may have an effect, eg. With stress
is concern about children’s sleep unique to this decade
no!
- eg. Letting a baby sleep on it’s back is likely to damage its skull (1983) — now told to put baby to sleep on back up to a year old
chidlren’s sleep findings around the 20th century
Around the 20th century, concern about children’s sleep was publicized as being a problem that needed a lot of attention
why was children’s sleep around the 20th century publicized as a probelm?
- Ownership of larger houses
- Reductions in family size and infant mortality rates
- People are having fewer kids and the kids they did have are living longer
- Reductions in the number of live-in maids that were responsible for childcare
- Growth of disciplines of medicine and behavioural psychology and popular media providing advice about health issues
- Modern inventions of the time (20’s and 30’s) were believed to disturb babies (e.g., electric lighting, radio, movie theatres, cars, appliances)
- Activities like listening to the radio and reading were believed to deprive children of sleep — experts believed this at the time
- Magazines aimed at women often had stories about inadequate sleep in children
what is co-sleeping?
Co-sleeping is practice of a newborn or young infant sharing a sleeping surface with a mother
prevalence of co-sleeping?
- Co-sleeping is virtually universal in some countries (e.g., some African countries, Mongolia)
- Only 6% respondents practiced co-sleeping in other countries (e.g., Italy, Israel, Ukraine)
published opinions on co-sleeping?
41% were negative, 28% positive, rest didn’t say anything
what is the controversy about co-sleeping?
- For: It is natural, consistent with primate and human biology
- Against: Increased the risk to infants of smothering, may slow the development of independence and self-regulation
reasons for negative opinions of co-sleeping?
unresolved issue of SIDs
American association of paediatrics opinions of co-sleeping?
- Risk of SIDS or smothering infants if they co-sleep on soft surfaces
- Increased risk if parents overly sleepy due to drugs or alcohol
- Increased risk if infant exposed to smoking
- Recommends that infants sleep on their backs in same room, but in separate side bed without bedding
advocates of co-sleeping?
- Co-sleeping reduces risk by facilitating rapid response
- High risk conditions mostly attributed to points mentioned previously
- Statistical association of co-sleeping and SIDS does not mean co-sleeping is the cause of SIDS
how to respond to an infant crying during the night - St. James-Robert?
- close infant contact reduces total amount of crying relative to infants mostly sleeping in another room
- No differences in amount of inconsolable crying and fussing/crying for >3h daily
how best to support breastfeeding - Ball?
Correlational evidence that co-sleeping babies breastfeed longer than those in a side-bed
other health correlates of co-sleeping?
- Some studies find an association between infant sleep problems and co-sleeping
- Little evidence for long-lasting effects of infant co-sleeping on development (sleep quality and functional variables), compared to those that did not co-sleep
what about mothers - co-sleeping?
- Mothers who room-shared showed objectively poorer sleep quality than those who did not
- Fussy infants unable to self-soothe brought into parental bedroom and therefore disrupt sleep?
- Infant in the bed means mother more likely to detect and respond to normal sounds?
describing and recording motivations for co-sleeping is…
difficult
types of cosleeping
reactive and intentional
reactive cosleeping?
baby is fussing, going to bring it in the bed with me
intentional cosleeping?
mom intended from the start to have the baby in the bed
important to consider regarding cosleeping: pre-industrial societies?
fertility rates were high, but so were infant mortality rates
important to consider regarding cosleeping: industrialization
fertility rates and infant mortality rates decreased
was cosleeping likely a risk in pre-industralized/traditional socieites?
Co-sleeping was likely a very minor risk in pre-industrialized/traditional societies and likely did not impede population growth
sleep in animals!!
We can pick out what sleep looks like in mammals, but with other animals it can be very difficult
measuring sleep across species, what is often used in neuroscience?
fruit flies are often used as a model in neuroscience, but how do we know if they’re sleeping?
can EEG criteria for sleep in humans be useful in other animals
yes, can be used to a large extent in mammals/birds
where do EEG signals come from in mammals?
neocortex
what is a comparable structure to cerebral cortex/neocortex in birds?
hyperstriatum
many of the basic cellular elements that make up the mammalian neocortex appear to be…
- homologous to those found in birds (ancient, common evolutionary origin)
- Being conserved among species, important
EEG patterns in birds and mammals?
- Low-amplitude activity during REM sleep
- REM episodes typically very brief in birds (<10s) relative to mammals
- No evidence of sleep spindles (or K-complexes) in birds
EEG patterns in other vertebraes?
- It is clear that reptiles, amphibians, and fish sleep
- Some evidence for homologous brain structures between reptiles, mammals, and birds, but the anatomy is quite different
- Electrophysiological features recorded from reptile cerebral structures not identical to those seen in NREM and REM sleep in birds and mammals
– > Most researchers argue that reptiles lack REM sleep
invertebrates examples?
insects, snails, starfish, jellyfish
are nervous systems similar in vertebrates/invertebrates?
- Nervous systems are very different than mammals and reptiles
- It is unlikely that EEG recordings would appear similar to those from mammalian brains
- So, are invertebrates sleeping? How do we tell?
behavioural criteria for identifying sleep in any species?
- During preparation for sleep, the animal orients towards a specific sleeping site and adopts a species-characteristic posture — orangutangs build a nest
- The animal becomes immobile (i.e., stops voluntary activity and show reduced mobility)
- The animal shows an elevated threshold for reactivity and arouse in response to external stimuli
- Moderately intense stimuli lead to more or less rapid reversal of state to full waking
- Deprivation of the opportunity to sleep leads subsequently to increased pressure to sleep (i.e., an increased probability of falling asleep) and to a rebound increase in sleep duration
what is deprivation of opportunity to sleep and implications?
(i.e., lost sleep is, at least partially, compensated for during a recovery opportunity). In other words, sleep is homeostatically regulated
- depriving them of sleep/disturbing them when sleep we see more of that
in what animals are deprivation effects time-of-day dependent?
fruit flies and cockroaches
what can the behavioural criteria for identifying sleep in any species be used to do?
distinguish sleep in animals from other states like stupor, torpor, or coma
broadly applicable definition of sleep across species?
Sleep consists of one or more neurobehavioural states that are rapidly reversible to waking by moderate sensory stimulation. It is characterized by unique patterns of neural activity and regulated by homeostatic and circadian mechanisms. During sleep, animals adopt a species-typical posture/location, show reduced activity and diminished, but not absent, responsiveness to environmental stimuli.
behavioural criteria for assessing sleep - invertebrates
all criteria can be used, although seeing 3/4/5 can be more challenging for invertebrates
do invertebrate and mammalian sleeping states serve similar functions?
In fruit flies and honeybees, there is evidence that sleeping after learning facilitated later retrieval of learned information
honey bees and sleep, sleep deprivation..
impairs precision of waggle dance signaling in honeybees
honey bee sleep deprivation
Directional precision was lower (i.e., greater SD of dance angles) in the treatment bees than in the control bees after a night of sleep deprivation compared with on the control day after DD (z= 2.36; one-tailed, P= 0.0499;n= 545 observations of 17 bees)
