Sleep Flashcards
What is responsible for controlling the circadian rhythm of the sleep-wake cycle?
Suprachiasmatic nucles
What is melatonin secreted by and what is its function?
Pineal gland
Modulates brainstem circuits that govern sleep-wake cycle
Synthesis increases as light decreases
Describe the interaction between the SCN and melatonin
SCN produces alerting signals and opposes the sleep load
Melatonin attenuates the alterting signals from the SCAN, causing wakefulness to decrease and sleep to occur
When melatonin levels drop in the morning, alerting signals increase again
What is sleep gate?
Time of maximum sleep drive (homeostatic) and minimum circadian drive (wakefulness)
What stages comprise NREM sleep?
Stages 1-3
Describe stage 1 sleep
Drowsy period
Slightly lower frequency and higher amplitude EEG waves - theta waves
Describe stage 2 sleep
Presence of sleep spindles on EEG
K-complex about every two minutes
Describe stage 3 sleep
Slow wave sleep
Deepest level of sleep
Low frequency, high amplitude EEG - delta waves
Difficult to awake people
What physiological changes occur in NREM sleep?
Decrease in muscle tone, HR, breathing, BP, metabolic rate, temp
Reduced movement, but tossing and turning can occur
Sleepwalking and sleep talking
Describe REM sleep
EEG similar to awake state
Increase in BP, HR, metabolism
Dreaming
Large muscle paralysis
Newborns spend more time in this stage than adults
What is REM rebound?
If deprived of REM sleep, the individual will make up for it at the next opportunity by going directly into REM sleep
Describe the cycles of REM/NREM sleep
After REM, brain cycles back through NREM
N3 generally occurs in the second cycle, but not again
4-6 additional periods of REM sleep, every 90 ,imutes
REM duration increases with each cycle
What is the role of the reticular activating system during sleep?
Cholinergic neurons project to thalamocortical neurons
Active during waking and REM sleep, quiet during NREM
Active RAS stimulates cortex and PNS, which sends positive feedback signals to RAS
RAS stimulation causes awakening of sleeping animal
What is the role of the Thalamus in sleep?
Gates sensory information, blocks input during sleep
Patterned interaction between thalamus and cortex important for sleep
When stimulated, causes awake animal to fall asleep
What NTs are present in wakefulness?
Monoamines: DA, NE, 5-HT
ACh
Histamine
Orexin/hypocretin
What NTs are present in sleep?
Adenosine
GABA
Melatonin
Galanin
What is the role of the ventrolateral preoptic nucleus in sleep?
Active, inhibit neurons responsible for wakefulness
What is Insomnia?
Inability to sleep of sufficient length of time
Stress, anxiety, caffeine, depression, medications
What is obstructive sleep apnea?
Interrupted breathing during sleep caused by partial or complete blockage of upper airway
Breathing efforts increase in an attempt to get more O2
Little or no SWS and REM sleep occur due to constant waking
What is SIDS?
Infants unable to arouse from SWS
May be caused by immature breathing control system
What is restless leg syndrome?
Discomfort in legs at night
Helped by moving legs
What is Narcolepsy?
Excessive daytime sleepiness
May have frequent REM sleep without going through NREM
Lose muscle control during emotional episodes
Hallucinations, sleep paralysis can occur
What is REM sleep behavior disorder (RBD)?
Affected individuals kick, punch, and otherwise act out aggressive dream scenarios while asleep
Affects men over 50
Brainstem disorder that prevents muscle paralysis
How does sleep change with aging?
Older individuals tend to sleep more lightly and for shorter times, but still need the same amount of sleep
Pineal gland produces less melatonin
