Sleep, Circadian Rhythms, and Sleep Disorders Flashcards
Where in the brain is the biological/circadian master clock?
The suprachiasmatic nucleus (SCN)
What two “systems” provide the drive for sleep? What’s the take-home point about their interaction?
Circadian (SCN, light, etc.)
Homeostatic sleep need.
Sometimes you have a homeostatic sleep need, but you can’t sleep well because it’s not lined up with what you’re circadian system wants.
What color of ambient light most promotes wakefulness?
Blue light. (it’s why it’s bad to look at computer screens at night)
What’s the path for ambient light information to the pineal gland?
Retina -> retinohypothalamic tract -> SCN -> superior cervical ganglion -> pineal gland (for melatonin release, or not)
What’s the main hormone telling you to go to sleep?
Melatonin
What’s the main hormone telling you to wake up?
Cortisol.
Is the SCN the only circadian rhythm clock in the body?
No. Every organ appears to have circadian rhythms, but they’re controlled to some extent by the SCN.
Do people’s circadian rhythms ever adjust to night shift work?
Nope. Working at night produces additional sleep pressure that can’t be slept away because people have trouble sleeping during the daytime.
6 elements of a polysomnography?
EEG Eye movements Muscle activity EKG Respiration Behavioral activity
3 important factors for full “recovery” during sleep?
Continuity (passing through the proper stages at the proper time)
Depth (getting to proper sleep stages)
Duration
What is slow wave sleep (SWS)? What parts of the brain are synchronized?
Deep sleep. High amplitude, low-frequency brain waves.
Thalamo-cortical and thalmo-reticular connections are have slow oscillations.
What does the EEG for REM sleep look like?
It looks like the person is awake, but the person is paralyzed.
What’s a hypnogram? How does the beginning of the night differ from the end of the night?
Graph of different sleep stages and the time in which the patient is in them. People have more slow-wave sleep (SWS) early in the night, with more frequent bouts of REM before waking.
Is muscle tone (except for the eye muscles) normal, or low during REM?
low
Is muscle tone normal or low during slow wave sleep?
Normal.
What might be the key “sleep switch?”
The VLPO - ventrolateral preoptic nucleus of the hypothalamus.
Do newborns sleep less than adults?
Nope. They sleep a lot more, but they sleep in short, rapid cycles.
What areas of the brain have been shown in PET scans to have less activity when sleep-deprived? (4 areas)
Thalamus, prefrontal cortex, inferior parietal lobe, occipital cortex.
Clinically, if you have a patient who’s really sleep deprived, what’s an immediate concern you should address?
How are they getting home, i.e. will they be driving?
What is “wake state instability” and how is it measured experimentally?
Wake state instability refers to stochastic variability in attention / response time that occurs when sleep-deprived.
It’s measured by recording latency when trying to press a button after a light blinks.
Are people generally conscious of how poorly they perform when sleep deprived?
Nope.
Can you still learn while sleepy?
Yes, but your cognitive speed is much lower.
Should you ever stay up all night when you have a running sleep debt?
No. Your cognitive performance falls through the floor.
Does everybody need the same amount of sleep / do poorly on little sleep?
No. Some people are very susceptible to missing sleep, some people barely perform worse at all when sleep deprived.
Is the danger of residency more about working long hours or not getting enough sleep?
Not getting enough sleep.
Are naps effective at increasing performance when sleep deprived?
Yep.
