Sleep Physiology and Sleep Disorders Flashcards
What is sleep?
- normal, recurring, reversible state
- not conscious
- not fully aware of self and the environment
- not unconscious
- can respond when stimulated
Sleep lies in between- can be awoken therefore not coma
Regarding REM and NREM sleep, which is at the start of the night and which is at the end?
- More NREM at start of night
- REM mostly at end of night
Regarding REM and NREM sleep, which of these is very important for children but essentially disposable for adults?
REM sleep
throughout lifetime amount of NREM sleep you have stays fairly consistent whereas REM sleep hours drop dramatically
Describe the physiology of NREM sleep?
- synchronised, rhythmic EEG activity
- partial muscle relaxation
- reduced cerebral blood flow
- reduced heart rate
- reduced B.P
- reduced tidal volumes
Describe the physiology of REM sleep
- EEG shows fast activity
- fMRI shows increased brain activity
- similar to wakefulness
- atonic muscles
- muscle tone is amazingly relaxed
- this doesn’t include respiratory muscles, for obvious reasons
- also doesn’t include ocular muscles but we’re not sure why
- cerebral blood flow increased
- impaired thermal regulation
What kind of dreams do you get in REM sleep?
narrative dreaming
What kind of dreaming do you get in NREM sleep?
Some non-narrative images
When you wake up with a strong emotion (either good or bad) but not remembering it.
How should we think of REM sleep (for adults)?
What evidence is there to suggest it’s dispensiblity
See it as “non-wakefulness, not sleep”
Dolphins have no REM sleep but highly functioning brains
Common drugs (tricyclics) suppress REM sleep with no effect
Which 3 processes/responses are important to remember when considering sleep?
- Homeostatic response
- the longer you’re awake the more likely you are to need sleep
- Emotional response
- in time of stress (e.g. exam) don’t fully sleep
- makes sense evolutionarily
- Circadian response
- 4am and 2pm are the two sleepiest parts of the day
Does psychology or biology&physiology control sleep?
Biology and physiology control sleep
Look at WW1 soldiers falling asleep on sentry duty despite knowing they’d be executed for it.
If you get 8 hours sleep a night and feel sleepy at 2pm it’s not because you’re not getting enough sleep it’s because that’s the sleepy point on your circardian rhythm.
Sleep is controlled by physiology and biology; not psychology
What is the circardian rhythm involved in?
The circardian rhythm important for sleep-wake, appetite, hormone secretion
Do the timings of the Circadian rhythm remain the same throughout your life?
NO
adolescents show a delayed sleep pattern
elderly show an advanced sleep pattern
- educationalists in USA did a 6 week study where they had students come into school later and leave later. Student perfomance went up & attendance went up while sickness went down. But it had the opposite effect on teaching staff.
How long is the natural circadian rhythm?
Why is it not this length of time in real life?
From studies based on blind people and people in caves (closed environments where they could choose to have light but otherwise didn’t) show circadian rhythm is 25 hours.
Recent studies suggest it may be closer to 24 hours 20 mins.
In real life light modifies natural body clock
How does the body clock “re-set”?
Retinal ganglion cells projecting to suprachiasmatic nucleus
- the non-rod, non-cone cells recieve blue light/bright light and this is the cell we believe resets the body clock
