Sleep_Physiology_Flashcards
(26 cards)
What are the two main types of sleep?
Non-Rapid Eye Movement (NREM) sleep and Rapid Eye Movement (REM) sleep.
How does sleep progress throughout the night?
Sleep cycles between NREM and REM, with REM increasing as the night progresses.
What characterizes Stage 1 (N1) sleep?
Light sleep, transition from wakefulness, lasts 1-7 minutes, low-voltage mixed-frequency waves.
What are sleep spindles and K-complexes, and in which stage do they appear?
They appear in Stage 2 (N2). Sleep spindles are bursts of high-frequency waves linked to memory, and K-complexes are large waves responding to external stimuli.
What is the function of Stage 3 and 4 (Slow-Wave Sleep)?
Deep sleep, tissue repair, immune strengthening, growth hormone release, hardest to wake from.
What brain waves dominate Slow-Wave Sleep?
Delta waves (low-frequency, high-amplitude).
What is a defining feature of REM sleep?
Rapid eye movements, muscle atonia (paralysis), vivid dreams, irregular breathing and heart rate.
Which neurotransmitter is most active during REM sleep?
Acetylcholine (ACh).
Why does muscle atonia occur during REM sleep?
To prevent acting out dreams.
Which part of the night has the longest REM sleep periods?
The last third of the night.
What are the two main processes regulating sleep?
Process S (homeostatic sleep drive) and Process C (circadian rhythm).
What role does adenosine play in sleep?
Adenosine builds up during wakefulness and promotes sleep by activating VLPO neurons.
How does caffeine affect sleep?
Caffeine blocks adenosine receptors, delaying sleep onset.
Which brain structure is responsible for the circadian rhythm?
The Suprachiasmatic Nucleus (SCN) in the hypothalamus.
Which brain region promotes sleep onset?
Ventrolateral Preoptic Nucleus (VLPO) in the hypothalamus.
Which neurotransmitters promote wakefulness?
Norepinephrine, serotonin, dopamine, histamine, acetylcholine, and orexin.
What is the role of the Locus Coeruleus in sleep-wake regulation?
Releases norepinephrine to promote wakefulness.
What happens in narcolepsy?
Loss of orexin neurons leads to sudden sleep attacks and muscle weakness (cataplexy).
How is REM sleep initiated?
Cholinergic neurons (REM-on) activate, while monoaminergic neurons (REM-off) are suppressed.
What happens to norepinephrine and serotonin during REM sleep?
They are nearly absent, allowing REM to occur.
How does sleep affect heart rate and blood pressure?
Both decrease during NREM but become irregular in REM.
What happens to breathing during REM sleep?
It becomes shallow and irregular.
Which hormone is released during sleep to regulate circadian rhythms?
Melatonin, produced by the pineal gland.
What is insomnia?
Difficulty falling or staying asleep due to overactive arousal centers.
