What are the basic patterns of normal sleep relative to understanding abnormal sleep architecture in fibromyalgia?

Updated: Apr 23, 2020
  • Author: Chad S Boomershine, MD, PhD, CPI, CPT; Chief Editor: Herbert S Diamond, MD  more...
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To understand abnormal sleep architecture, it is essential to know the basics of normal sleep. Sleep can be divided into 2 main parts: nonrapid eye movement (NREM) and rapid eye movement (REM), which alternate cyclically through the night, always starting with NREM sleep. In each successive cycle through the night, NREM sleep decreases, and REM sleep increases. Each cycle, NREM plus REM, lasts about 90 minutes.

NREM is divided into 4 stages:

  • Stage 1 – Initial drowsiness

  • Stage 2 – Light sleep

  • Stages 3 and 4 – Progressively deeper levels of sleep.

In stages 3 and 4, an electroencephalogram (EEG) will show delta waves, which are high-amplitude (>75 mV) waves that move slowly (0.5-2 Hz). Much of the body's regulatory work, as well as the synthesis of many substances (eg, antibodies, growth hormone, other neurochemicals), occurs during NREM sleep.

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