Final answer:
Sleep rebound is when a sleep-deprived person falls asleep more quickly during subsequent opportunities for sleep. It is a result of homeostatic regulation of sleep.
Step-by-step explanation:
When a sleep-deprived person takes longer to fall asleep during subsequent opportunities for sleep, it is called sleep rebound. Sleep rebound refers to the phenomenon where a sleep-deprived individual will fall asleep more quickly during the next chance to sleep, as a way of compensating for the lost sleep. This is due to the homeostatic regulation of sleep, which is the body's way of maintaining a balance in sleep-wake cycles.