What is the term for the phenomenon where sleep-deprived individuals take longer to sleep during later opportunities?

Sleep rebound refers to the phenomenon where individuals who are sleep-deprived experience a significant increase in sleep duration and depth during subsequent sleep opportunities. This usually occurs when they are finally able to sleep after being deprived, leading to a compensatory response from the body to recover lost sleep. Essentially, the body tries to make up for the deficiency by inducing longer sleep episodes characterized by more time spent in the deeper stages of sleep, which is crucial for physical and cognitive recovery.

In the context of the question, sleep rebound captures the essence of how sleep-deprived individuals take longer to initiate sleep during their upcoming opportunities, typically as their bodies signal the need for increased restorative sleep. This response can sometimes manifest as longer sleep times or deeper sleep over the next few nights in an effort to counteract the impacts of the previous lack of sleep.

The other options address different sleep-related concepts. Sleep latency refers to the time it takes for an individual to transition from full wakefulness to sleep. Sleep fragmentation describes interruptions during sleep that can lead to poor sleep quality. Sleep deprivation itself is a condition resulting from inadequate sleep quantity or quality but does not specifically describe the increased time it takes to sleep later, which is distinctly highlighted by the concept of sleep rebound.