Sleep Flashcards
(38 cards)
circadian rhythms
functions that have a 24 hr rhythm
may be behavioral, physiological, or biochemical- eg. thirst, body temp, hormone levels= all have biological origin
diurnal
active during the light
nocturnal
active during the dark
biological clocks
leads to precise timing
endogenous- not quite 24 hr
entrain- (set) to light-dark cycles
entrain clock
with continuous dim light, behavior becomes free-running
when the light cycle shifts, the behavior also shifts
what allows for entrainment?
light (visual input)
meals
sleep
jobs/class
activity (exercise)
several of these inputs are also regulated by the biological clock
suprachiasmatic nucleus (SCN)
biological clock in SCN in hypothalamus
when SCN is damaged
if light/dark cycle maintained, no change in behavior
if only dim light, random behavior
isolated SCN neurons
can create circadian rhythm via chemical release (encapsulated in plastic)
SCN sequence
happens in a cycle (takes around 24 hrs- per/cry rises in light)
1. clock and cycle bind to form dimer
2. clock/cycle cause per and cry transcription
3. per and cry dimerize
4. per/cry inhibit clock/cycle activity
5. over time, per and cry degrade
6. allow clock and cycle to dimerize
molecular clock based on cyclical levels of :
clock and cycle/Bmal1
per (period) and cry (cryptochrome)
how does light information reach SCN?
retinal ganglion cells (RGC) project to SCN (retinohypothalamic pathway)
retinal ganglion cells (RGC)
RGC do not get information from rod and cone cells
RGC contain melanopsin (sensitive to light, especially blue light)
retinohypothalamic pathway
- light causes glutamate release in SCN
- glutamate increases Per and Cry transcription
- synchronizes SCN neurons to each other and light/dark cycle
classes of sleep
non-REM sleep (NREM)
rapid-eye-movement sleep (REM)
monitoring sleep
electroencephalography (EEG)
electro-oculography (EOG)
electromyography (EMG)
EEG
measures brain waves- brain potentials
synchronized routes of action potentials
EOG
eye movements
EMG
muscle tension
non-REM sleep
has 3 stages and a reduction in postural tension
REM sleep
has small-amplitude & fast EEG waves, no postural tension, and rapid eye movement
stages of sleep
90-110 min
NREM (stages 1-3)
REM
waking
while alert: mix of fast frequencies and low amplitude waves
called beta activity of desynchronized EEG
stage 2
sleep spindles
if waken up during stage 1 or 2, the person may deny they were sleeping
