Sleep Flashcards
List the stages of sleep and what happens in each
awake – alpha activity, regular, medium frequency 8-12 Hz (more prevalent with eyes closed); beta activity, irregular, low amplitude 13-30 Hz.
stage 1 – theta activity 3.5-7.5 Hz – transition.
- > starting to fall asleep
- > transition state, starting to sleep, easy to wake up,irregular activity of brain
stage 2 – irregular, periods of theta, sleep spindles (short bursts at 12-14 Hz – maintenance of sleep), K-complexes (≈1 per minute).
- > muscle tone decreases, heart arte slows
- > starting to enter deep sleep
- > ppl who have trouble sleeping have trouble staying in this stage
stage 3 – high amplitude delta >3.5 Hz.
-> more than 20%< 50% delta
stage 4 – 50% delta activity.
- 15% of time is spent here
- sleep walking talking terrors
- deep sleep muscles are relaxed
stages 3 & 4 - slow wave sleep.
REM sleep
desynchronized EEG, some theta, rapid eye movements.
- dream sleep
body largely paralyzed.
adults spend 25% of time here
newborns spend 50%
Sleep stages
90 minute cycle between REM and non-REM sleep.
Why do we sleep?
we spend 1/3 of our lives sleeping if we don’t sleep enough we can die
- it keeps us alive
- restores body metabolic product
- we don’t rly know why we sleep
1/3= restorative
last 1/3= dreaming
How can sleep disorders be characterized?
1) insomnia- can’t sleep
2) excessive- daytime sleep to much sleep
3) parasomnia- events happen while person sleep and person doesn’t know
Dreaming
increased cerebral blood flow to visual cortex and decreased to inferior frontal- protective mechanism
decreased activity (decreased planning, sequencing of events
increased activity (increased, vivid imagery)
- Insomnia
Margaret Thatcher (and Winston Churchill) slept only a few hours a night!
underlying cause – insomnia is a symptom.
medication can be a curse – sleep medication hangover!
sleep apnea
difficulty breathing while asleep (people who snore have brief periods of apnea).
- throat closes and lungs don’t get enough of oxygen brain gets message and wakes you happens many times
Narcolepsy
sleep attack – at inappropriate times (particularly during monotonous or boring conditions).
≈ 2 – 5 minutes.
sleep paralysis and hypnagogic hallucinations (hallucinations during the transitional state between being awake and sleeping) – alien abduction?
cataplexy
falling to ground - hypocretin deficiency – dogs.
REM sleep behaviour disorder
acting out! can be quite dangerous – males dreaming their wives are being attacked will hit out at the attacker – sometimes hitting their wives! women do it too… failure to inhibit movement during REM. * link between Rem and parkinson's
Slow-wave sleep
usually during stage 4 sleep.
nocturnal enuresis – bedwetting.
somnambulism – sleep walking – different than REM sleep acting out.
pavor nocturnis – night terrors.
usually evident in childhood – resolve naturally.
Why do we sleep?
brain rest?
only warm-blooded vertebrates exhibit REM.
necessary for survival? – Indus Dolphin. Deal with swift currents (sleep 7 hours a day but in 4 to 60s intervals).
bottlenose dolphin & porpoise sleep one hemisphere at a time!
- keeps one hemisphere alert.
What is REM sleep important for?
perhaps slow wave sleep is restorative but REM sleep is important for development (higher portion of REM during stages of development).
consolidation OR clean up?
Largest increase in REM sleep associated with largest increase in performance.
What happens with Sleep over the life span?
in general we require less sleep as we get older.
the proportion of REM sleep needed also decreases.
arousal
– level of alertness (a continuum).
adenosine
neuromodulator that plays a role in the initiation of sleep.
Acetylcholine
– agonists increase EEG signs of arousal; antagonists decrease EEG signs.
Norepinephrine
catecholamine agonists (e.g., speed) increase arousal via noradrenergic system in the locus coeruleus.
Serotonin (5-HT)
– increases relate to locomotion and cortical arousal – facilitating ongoing behaviours.
Histamine
– direct effect on cortex, indirect affect via ACh induced changes.
ventrolateral preoptic area:
A group of GABAergic neurons in the preoptic area whose activity suppresses alertness and behavioral arousal and promotes sleep.
areas are reciprocally connected by inhibitory GABAergic neurons.
What controls REM sleep?
REM sleep is controlled by a flip-flop similar to the one that controls cycles of sleep and waking.
The sleep/waking flip-flop determines when we wake and when we sleep, and once we fall asleep, the REM flip-flop controls our cycles of REM sleep and slow-wave sleep.
ACh release in the dorsolateral pons.
basal forebrain connections produce arousal & cortical desynchrony.
REMs arise from connections with the tectum.
Biological Clocks
90 minute activity / rest cycle
- every 1 hr 30 mins its good to take rest
24 hour sleep / wake cycle
Circannual
yearly
- migratory cycles of birds
Infradian
- less than a year
- human menstrual cycle
Circadian
daily
- sleep wake cycle
A daily rhythmical change in behavior or physiological process.
Ultradian
less than a day
- eating cycles
zeitgeber
a stimulus (usually the light of dawn) that resets the internal clock responsible for circadian rhythms.
passive response to changes in light conditions (living in Resolute would be tough).
direct projections from retina provide the zeitgeber information about light.
suprachaismatic nucleus (SCN)
contains a biological clock that is responsible for organizing many of the body’s circadian rhythms (including sleep/wake cycle).
Seasonal rhythms
breeding rhythms that begin as day lengths increase and end as they begin to decrease.
pineal gland secretes melatonin during the night – more produced during long nights of winter signaling the season.
SADS – seasonal affective disorder – a decrease in melatonin levels?
light phase of the circadian rhythm may be too short.
Jet lag
Shift-wo
