- (C) About an hour into one’s first sleep cycle, people are typically in stage 3 or 4. In these stages,
they experience deep, slow-wave sleep, which is marked by the presence of delta waves. Alpha
waves indicate drowsiness, beta waves are present when one is awake and alert, and sleep
spindles and K complex waves occur mostly in stage 2.
marvins-underground-k-12
(Marvins-Underground-K-12)
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