Sleep and Wakefulness Flashcards
(27 cards)
What are circadian rhythms? Internal mechanisms operating on a 24-hour cycle affecting sleep
temperature
What is a zeitgeber? A stimulus that resets the circadian rhythm
such as sunlight
What is jet lag? Disruption of circadian rhythms due to crossing time zones; harder when flying east.
How does shift work affect sleep? It disrupts circadian rhythms; adaptation is better with complete darkness during day and bright light at night.
What brain structure controls circadian rhythms? The suprachiasmatic nucleus (SCN) in the hypothalamus.
How does light reset the SCN? Via the retinohypothalamic path
involving ganglion cells with melanopsin.
What genes influence circadian rhythms? Period (PER) and timeless (TIM) genes.
What does melatonin do? Secreted by the pineal gland; increases sleepiness and resets the biological clock.
What is sleep? A state produced by the brain with decreased activity and responsiveness.
What are the stages of sleep? Stage 1
2
What are sleep spindles and K-complexes? Stage 2 sleep features: spindles are bursts of 12–14 Hz waves
K-complexes are sharp waves that inhibit neurons.
What characterizes slow-wave sleep (SWS)? Stages 3 and 4; slow
large EEG waves
What is REM sleep? Rapid Eye Movement sleep with fast EEG waves
muscle relaxation
What is the function of the reticular formation? Part of the brainstem involved in arousal and wakefulness.
What does the locus coeruleus do? Releases norepinephrine
enhancing alertness and suppressing REM.
What neurotransmitters are involved in sleep/wake cycles? GABA (inhibitory)
acetylcholine (excitatory)
What are PGO waves? Electrical potentials seen during REM sleep starting in the pons
then LGN
What is insomnia? Inadequate sleep due to various causes including stress
meds
What is sleep apnea? Inability to breathe while sleeping; linked to heart problems and cognitive issues.
What is narcolepsy? Sleep disorder with sudden sleep attacks
cataplexy
What causes narcolepsy? Lack of hypothalamic cells that produce orexin.
What is periodic limb movement disorder? Involuntary limb movement during sleep
mostly in NREM.
What is REM behavior disorder? Vigorous movement during REM due to inadequate GABA.
What are night terrors and sleepwalking? Night terrors involve intense fear in NREM; sleepwalking occurs in stages 3–4.
