Circadian Rhythms
Zeitgeber
Why do we stick to circadian rhythms?
Hamsters: nocturnal
hamsters sleep:
Constant lighting:
Why do we stick to circadian rhythms?
Circadian rhythms
What happens without the SCN?
Lesion of the SCN
SCN lesion & dim lighting
Why do we stick to circadian rhythms?
interim review
the optic nerve
Melanopsin
Melanopsin
Melanopsin - light
Melanopsin : dark
Melatonin & circadian rhythm
exogenous melatonin - a sleep aid?
Melatonin (relative to placebo)
insomnia
melatonin
EEG
REM
Spetogram of EEG
What is sleep?
Awake/alert
Eyes closed, relaxed
Stage 1
Stage 2
Stages 3&4
REM sleep
Stage 2: K-complexes reflect neuronal "down-states"
cortical neurons "down-states"
K-complexes in stage 2 lead to theta and delta waves in slow-wave sleep (SWS) in stages 3 & 4
Sleep Cycle
REM sleep looks like wakefulness
Motor neurons are inhibited during REM
REM sleep looks like wakefulness
REM sleep & dreaming
Broad categories of sleep disorders
insomnia
Insomnia (lack of sleep)
Most sleep-aide drugs come with chance of dependency
Hypersomnia (too much sleep)
orexin neurons in the hypothalamus serve as sleep/wake "switch"
Narcolepsy treatment
