REM rebound is described as which phenomenon?

• A. Decrease in REM sleep after deprivation
• B. No change in REM sleep after deprivation
• C. Increase in REM sleep amount/density after REM deprivation or withdrawal from REM-suppressing drugs
• D. Increase in slow-wave sleep

Answer: (C)

REM rebound comes from the brain’s need to compensate after REM sleep loss. When REM sleep is deprived or REM-suppressing drugs are withdrawn, the brain builds up a REM debt. In subsequent sleep, it delivers more REM than usual—increased total REM time and/or greater REM density—and often the first REM period appears sooner. This recovery is specific to REM, not a general boost in deep slow-wave sleep, which would be a different kind of rebound.