Sleep physiology and disorders Flashcards
What is sleep?
Reversible behavioral state of perceptual disengagement from, and unresponsiveness to, the environment
Is sleep essential for health? Can sleep deprivation lead to death?
Yes and yes
What regulates sleep?
Dienchephalic and brainstem nuclei
What does ambient light impinge upon?
Ganglion cells that contain the photopigment melanopsin.
The retinal ganglion cells are inhibited and stimulated by what?
Inhibited by ambient light
Stimulated by darkness
What do the retinal ganglion cells do with decreasing ambient light?
Fire off electrical signals to the suprachiasmatic nucleus.
What does the suprachiasmatic nucleus do?
Activates the paraventricular nucleus (PVN)
What is the role of the PVN?
It is a sympathetic nucleus that activates neurons in the intermedilateral gray zone of the upper spinal cord that modulate neurons in the superior cervical ganglia
Where do the sympathetic neurons of the cervical ganglia travel and what do they activate?
the pineal gland
What does the pineal gland do?
Synthesizes and releases melatonin
Role of melatonin?
Stimulates a drowsy state by modulating brainstem neurons to facilitate the onset of sleep
When does melatonin levels begin to rise? When do they peak?
Early evening, ~2:00 - 4:00 am
How is sleepiness measured?
Polysomnography
EEGs can be segregated into what classifications?
Beta >13 Hz
Alpha 8-13 Hz
Theta 4-7 Hz
Delta <4 Hz
How many stages of sleep are there?
Five
What are stages I - IV called? Stage V?
Non REM Sleep
REM Sleep
What is the lightest stage of sleep? The deepest?
Stage I
Stage IV
What is stage II of sleep characterized by?
Bursts of activity called sleep spindles and K complexes
The EEG characteristics of REM sleep are what compared to the awake sleep?
Very similar
EEG activity in awake state?
Alpha and beta
EEG activity in Stage 1 and Stage 2 sleep?
Theta activity