28a - Sleep Physiology & Disorders Flashcards
How do circadian rhythms influence sleep?
ambient light impinges on retinol ganglia cells that contain melanopsin. Retinol cells are inhibited by light and stimulated by darkness and sends AP to Suprachiasmic nucleus that then activates paraventricular nucleus (sympathetic) activates intermedialateral gray zone that modulate superior cervical ganglion. These activate pineal gland to synthesize and release melatonin. Melatonin stimulates drowsiness in brainstem neurons.
What are the different stages of sleep?
Awake - alpha+beta
stage 1 - lightest sleep, theta
stage 2 - sleep spindles, K complexes, Theta
stage 3 - delta
stage 4 - deepest, delta (low freq, high V)
stage 5=REM - similar to awake (fast freq, low V), theta+beta
full cycle is 90 min.
What are the physiological effects of sleep?
NREM - few eye movments, decreased HR, BP, RR, temp, fewer dreams, sleep walking. All maxed out at stage 4. PPT and LDT inactivated
REM - rapid eyes, muscle paralysis, HR, BP, RR, temp near awake levels, vivid and emotional dreams. Amygdala, parahippo, anterior cingulate, pedunculopontine and lateral dorsal tegmental areas active.
Frontal cortex and posterior cingulate inactive.
What is the cellular and molecular physiology of sleep?
locus cerulius provides noradrenergic input, dopaminergic cortical input, medial and lateral raphe nuclei serotonergic circuits are all active during wakefullness.
Histamine from tuberomamillary nucleus is high during wakefullness and decreases during NREM and REM. antihistamines make you sleepy.
How do you diagnose narcolepsy?
clinical presentation or low CSF hypocretin levels.
loss of hypocretin/orexin from posterior lateral hypothalamus.
genetic HLA gene DQ1.
What are treatments for narcolepsy
methylphenidate and modafinil for daytime sleepiness
TCAs and SSRIs for cataplexy (instant drop into sleeping)
How do you diagnose sleep apnea
apneic periods lasting longer than 10 seconds causing oxyhemoglobin desaturation of more than 4%.
more common in men and fatties.
What are treatments of sleep apnea?
CPAP, lose weight
How do you diagnose insomnia?
difficulty falling or remaining asleep. transient affects 50% of adults throughout their life.
chronic > 6 weeks affect 25% of adults.
How do you diagnose REM sleep behavior disorder?
loss of atonia during REM sleep causing acting out.
Can be caused by EtOH withdrawals, TCA and SSRI use.
How do you treat REM sleep behavior disorder?
clonazepam
What parts of the brain are inactivated during REM?
frontal cortex and posterior cingulate cortex
What parts of the brain are activated during REM?
PPT and LDT (awake zones) as well as amygdala, parahippocampal gyrus, anterior cingulate cortex
What is main activator of sleep?
VLPO
What are somnogens?
sleep chemicals
adenosine - declines in sleep
IL1b and TNF promote sleep
melatonin, made in darkness
What is action of locus cerulius and when is it active/inactive?
provides noradrenergic input.
active during wakefullness.
Silent during REM and NREM.
What is source of histominergic input for sleep/wakefullness?
tuberomamillary nucleus
What is source of orexin?
lateral hypothalamic nucleus
What does orexin do?
excitatory stimulus to forebrain and brainstem nuclei to facilitate wakefullness.
absent in 90% of narcoleptics
What is the VLPO and what does it do?
ventrolateral preoptic nucleus. GABAergic and galanin neurons which inhibit arousal nuclei. Causes NREM sleep. Main sleep initiator
What does multiple sleep latency test measure?
time required to fall asleep. People with sleep problems fall asleep faster in middle of day.
What is epworth sleepiness scale?
self-report tendency to fall asleep
When do you get morning wood?
REM sleep
