What phenomenon occurs when someone misses REM sleep in a night?

When a person misses REM sleep during a night, the phenomenon of REM rebound occurs. This means that after a period of deprivation from REM sleep, the body compensates by increasing the amount of time spent in REM sleep during subsequent sleep periods. This is a natural response of the body, as it strives to fulfill its need for REM sleep, which is believed to play a critical role in mood regulation, memory consolidation, and overall mental health.

Following periods of REM sleep deprivation, the brain can enter REM more quickly and for longer durations in an effort to restore the balance. Thus, if an individual experiences a night lacking REM sleep, the following sleep session may include extended bouts of REM to make up for the lost sleep, illustrating the body’s adaptive mechanism to prioritize REM stages when they're missed.