“There was constant exhaustion. It didn't matter how much I slept.” – Scott
Normally, wakefulness is promoted during the day by multiple interconnected neuronal systems, including acetylcholine, dopamine, histamine, norepinephrine, and serotonin neurons.1,2 Wakefulness is characterized by high muscle tone and fast-frequency neuronal activity that is necessary for alertness and higher-order neurocognitive functioning. 3,5 Learn more »
Non-REM sleep is a sleep state with slower-frequency neuronal activity and light to deep stages of non-REM sleep.3,5 Skeletal muscle tone is lower than during wakefulness.3,5 Nighttime sleep normally begins with an episode of non-REM sleep.3
During REM sleep, which is associated with dreaming and skeletal muscle atonia, neuronal activity is faster and desynchronized, with distinct wave patterns (e.g., sawtooth waves) on electroencephalogram (EEG).3,5,7 Episodes of REM sleep typically occur at night after non-REM sleep and become longer over the course of the night.3
Normal Sleep-Wake Cycle
A normal sleep-wake cycle is generally characterized by consolidated wakefulness during the day and predictable, alternating periods of non-REM and REM sleep at night, generally with infrequent awakenings.2,3,7
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