Sleep Phys Exam 1
Mechanisms on how sleep disruption might cause a physiological problem
In sleep apnea there is a lack of oxygen delivery and this could lead to myocardial ischemia/stroke because lack of oxygen going to brain or heart leads to reduced blood flow to that area.
2 process model of sleep
Process C (sleep propensity oscillates with a daily variation) -> affected by light/sun Process S (sleep propensity increase as waking accumulates and dissipates with sleep) -> affected by how much sleep you got last night
What is process S? What role does it play in sleep homeostasis?
Process S associated with hypnotoxins. Hypnotoxins are chemical basis for making an individual feel "tired". If you wake up tired you are likely to still have elevated hypnotoxins
EEG: wakefulness-concentratin
beta >12Hz
circadian controller? ultradian controller?
circadian controller is superchiasmatic nucleus in hypothalamus, and ultradian controller is unknown
how does cortical synaptic density change during first year and what does this do
cortical synaptic density increases during first year, provides appropriate substrate for synchronous EEG activity
As animal ages and develops, the time spent in REM
decreases
if brain is more developed at birth then
don't need as much as REM sleep during birth
Quiet sleep (QS) in newborn infants
even respiration, inactive, discontinuous EEG (trace alternant), no eye movements similar to NREM in adults
Light is a critical zeitgeber. how does it reset rhythms in a phase-dependent manner?
evening light (before 12am) pushes phase later (phase delay) -> wake up later and go to bed later morning light (after 12am) pulls phase earlier (phase advance) -> wake up earlier and go to bed sooner
how does advance sleep phase syndrome alter circadian rhythm
go to bed sooner, wake up earlier
SWS characteristics on EEG
high amplitude, low frequency
NREM sleep in mammals is characterized by
high voltage, slow synchronous EEG activity of the brain
what is phase advance vs phase delay
if wakeup and bed time are earlier than that is phase advance if bed and wakeup time are later than that is phase delay
vicious cycle of sleep apnea
increased CO2 and decreased O2 -> increase Q to maintain blood flow (SNS) ->Wake up and breathe -> go back to sleep -> decreased O2 -> increased SNS -> etc. *overactive sympathetic nervous system! (Both apneas)
name some behavioral and circumstantial factors that affect sleep patterns
life-style choices, SES, health, employment, school
REM sleep in mammals is characterized by
low voltage, fast asynchronous EEF activity of the brain
which animals sleep?
mammals and avians have NREM and REM sleep bc homeotherms (endothermns)
Why do old people sleep less than younger adults
medical illness, medications/polypharmacy, circadian rhythm disturbances, primary sleep disorders
loss of hypocretin cells, or mutations in the hypocretin receptors are associated with which sleeping disorder
narcolepsy
How did we measure respiratory airflow?
nasal cannula and oral thermistor
difference between ultradian and circadian rhythm
ultradian rhythm is a recurrent cycle repeated throughout a 24hr day circadian rhythm is a complete one day cycle, and is a self-sustained biological rhythm that is normally synchronized to a 24 hr period
Active sleep (AS) in newborn infants
uneven respiration, muscle twitches, continuous EEG activity, rapid-eye movement similar to REM in adults
EEG: wakefulness
alpha 8-12Hz
what percentage of sleep is spent in REM in mammals (endotherms)?
25% (5x energy requirement of ectotherm)
Key points of Yetish et all paper (pre-industrial societies)
-pre-industrial societies have similar sleep patterns to that of industrial society -light is not primary factor in regulation of sleep (most pre-industrial societies woke up BEFORE sunrise unlike modern society) -temperature is major regulator (sleep was associated with a decrease in core temperature) -seasonal affect (sleep on average 1hr longer in the winter)
NREM stages in newborns differentiated by
1-2months
when do sleep spindles appear in newborns
2-3months
SWS emerges at
3-6months
why do avians spend less time time in REM than mammals?
5% is REM compared to 25% REM in mammals (less body temp to maintain?)
sleep cycle length at birth vs mature
50min cycles at birth vs 60-90min cycles in adults want to get into REM more often
How much time does it take before first REM sleep
60-90minutes
sleep onset at birth for newborns
ACTIVE --> NREM (NREM--> REM in adult)
What is the subject of Siegel Paper (unearthing phylogenic roots)
Address diversity of sleep behaviors among mammals and the conservation of basic sleep mechanisms using genetic model organisms
In each successive cycle during sleep, amount of time spent in REM
Amount of time spent in REM increases throughout the night (every 60-90minutes)
REM sleep in amphibians and reptiles is characterized by?
Amphibians and reptiles do NOT have REM sleep
Active sleep at birth vs at 12mo
At birth active sleep is at 50% vs at 12mo its at 25% at birth need more REM for brain maturation
Stages in sleep in order (usually)
Awake-1-2-3-4-3-2-REM (enter REM sleep through stage 2)
Narcolepsy hypnogram
Being able to go from wakefulness to REM sleep (does not require stage 2 to enter REM)
Breathing in REM vs NREM
Breathing and tidal CO2 are variable in REM NREM- all breaths are identical
basic circadian clock tx factors
CLK(clock) and CYC (cycle) activates PER(period) and TIM (timeless) genes. PER and TIM proteins feedback and repress CLK and CYC
characteristics of sleep (5 characteristics)
DBHEN -Distinguishable from wakefulness (rapidly reversible) -Behavioral quiescence (reduced motor behavior) -Homeostatically Regulated (miss some, get more next time) -Elevated arousal thresholds (sensory and motor systems less active) -Not one homogenous state (NREM/SWS, REM/PS) -
Where did you place EEG, EOG, EMG electrodes
EEG: multiple electrodes placed on head, behind ears, glabella, and inion EOG: 2 electrodes placed on right and left temples EMG: 2 electrodes placed on chin
how would you know if REM or NREM? how would you know REM from wakefulness
EOG: increased EOG firing in REM EEG: low amp, high freq in REM similar EEG and EOG, but EMG would be different (v little activity during REM)
Components of the circadian rhythm
Input (light) -> transducer (retinal ganglion cells) -> pacemaker (superchiasmatic nucleus) -> regulated system -> output rhythm (melatonin, sleep-wake)
Sleep time for infants?
Is scattered, sleeps throughout the day and night regular sleeping pattern does not develop in newborns until 16-17 weeks
More SWS towards front of night/end of night?
Less likely to have SWS towards the end of the night
How would you know if subject is awake or sleep using EEG?
Low amplitude, high frequency: wakefulness or REM high amplitude, low frequency: SWS
Fact about history of sleep
Mairian (1729)- circadian rhythms discovered in plants Pieron (1910)- hypnotoxin (plasma of sleep deprived dogs induced sleep in non-sleep deprived dogs) Berger (1928)- brain electrical activity differences in sleep-> slow waves Brem Kleitman (1957): cyclical variation in EEF and eye movements Dement (1958) found out that there was an "activated" EEG during behavioral sleep
What tools was used to measure state of consciousness in sleep lab?
Measured using AlicePDX: -oral thermistor -nasal cannula -respiratory effort belts (thoracic and abdominal) -pulse oximetry -ECG -EEG -EOG -EMG
Breakdown of percent of time spent in stages
NREM (75%) REM (25%) S1: 5% S2: 45% (K complexes and sleep spindles) SWS: 25%
If you travel East and the time zone is 5 hours later than your hometown then how do you correct it?
So if you usually go to sleep at 10pm (3am in East) then should do a phase advance and go to sleep earlier and wake up earlier. (wear shades in the evening time so you can go to sleep earlier, less exposed to evening light and be exposed to light in the morning so you can pull phase earlier) gonna take you 5 days to adjust tho
If you travel West and the timezone is 5 hours before than your hometown then how do you correct it?
So if you usually sleep go to sleep at 10pm (7pm in West) then should do a phase delay and go to sleep later and wake up later. (be exposed to light in the evening time and wear shades in the morning so you can avoid your phase being pulled earlier-> phase delay)
How does daily REM sleep correlate with neonatal percent of adult brain weight?
The more potential your brain has to grow, the more REM sleep because you need more brain development/maintenance after birth.
EEG: Stage 1-2 EEG :Stage 3-4
Theta 3-7Hz Delta 0.5-2Hz
Total sleep time and REM changes with aging
Total sleep time generally decreases but REM stays pretty constant at 25%
Apnea hypnogram
airway closes everytime they fall asleep Minimum REM and consolidated sleep
without zeitgeber circadian clock
no light time giver, circadian clock shifts by 1hr every day (process C doesnt occur at the right time), slowly start sleeping later (delay) bc human circadian rhythms is greater than 24hr (25hr) ex. if no light for 20 days, circadian clock would shift 20 hours delays without light cue
How to distinguish between central and obstructive apnea?
obstructive apnea show effort in trying to breath (chest belt), central apneas do not(usually bc of brain problem not anatomical)
Sleep in elderly vs young?
older adults have less SWS (SWS decline by 40% in 2nd decade) ability to sleep decreases with age circadian clock naturally advances with age (older adults may get sleepier earlier in the evening and awaken earlier in the morning)
outputs of circadian timing system (melatonin, temp, cortisol)
plasma melatonin peaks during the night (pineal) core body temp decreases throughout the night (ANS) plasma cortisol is lowest at middle of night. increased melatonin leads to decreased temperature.
precocial vs altricial
precocial: developed ready to go at birth altricial: brain increased potential to develop over time
how is sleep distinguishable from wakefulness how is REM distinguishable from wakefulness
rapidly reversible EEG would have same high brain activity, EOG would be kinda the same, EMG is where it would be different where REM is not active and wakefulness is active
how does plasma cortisol change during sleep
reaches a low while you are sleeping peak cortisol levels upon waking
affect of pruning of cortical synpases across adolescent development (12-15years)
reduces EEG amplitude and SWS underlies development changes from childhood to adolescence
In precocial animals time in REM
remains constant as animal age and develops
Electroencephalogram (EEG) signals come from
signals from the cortex only (summation of cortical neuron firing)
where is sleep thought to have evolved?
sleep is thought to have arose from the need for endothermy
what does the diversity of sleep behaviors among mammals mean to functions of sleep?
sleep serves specific functions
ectotherm sleep
sleep with no SWS rapid eye movements during sleep with no REM sleep
what does it mean by sleep is "homeostatically regulated"
sometimes you get more or less sleep than usual, so if you get a poor night's sleep, the next night will result in more sleep
Species with greater brain maturation at birth have state concordance
state concordance(sleep patterns shifts to stage oriented (1-2-3etc.) precotial (increased brain maturation at birth) have state concordance earlier after birth
How did we measure respiratory effort?
thoracic and abdominal belts