A patient taking a monoamine oxidase inhibitor for depression reports total absence of REM sleep on polysomnography over 3 weeks. After the drug is stopped, which phenomenon is expected?
- A Permanent loss of REM sleep capacity
- B Gradual return of REM sleep to normal proportions over 6 months
- C REM rebound — an immediate, prolonged increase in REM sleep duration and density ✓
- D Conversion of REM sleep time to slow-wave sleep time proportionally
Correct answer: C. REM rebound — an immediate, prolonged increase in REM sleep duration and density
Explanation
MAO inhibitors suppress REM sleep by elevating monoamines (serotonin, norepinephrine) which inhibit REM-generating cholinergic neurons in the brainstem. Upon discontinuation, there is an intense REM rebound — REM sleep increases markedly in both proportion and eye movement density as the homeostatic pressure accumulated during suppression is discharged. This rebound can precipitate nightmares and is the physiological basis for the 'rebound' phenomenon observed with any REM-suppressing drug.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
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