Behavioral Science

CHAPTER 6
Sleep Science and
Disorders
NORMAL SLEEP
What are the normal stages of sleep?
REM (rapid eye movement) and NREM
(nonrapid eye movement). NREM is
divided into four stages: 1, 2, 3, and 4.
Awake
REM
Sleep stage
Stage 1
Stage 2
Stage 3
Stage 4
Time asleep
Figure 6.1
What is slow wave sleep? Slow wave sleep occurs during stages 3
and 4 of NREM sleep. It is also known
as delta sleep and is the deepest portion
of sleep. Electroencephalogram (EEG)
shows delta waves, which are the
lowest frequency waves.
Delta waves = Deep sleep
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