When you get less sleep than your body needs, you acquire “sleep debt.” All adults need about 7–8 (or more) hours of sleep per night in order to stay healthy and perform their best. If you get less, then you need extra sleep to make up for whatever was lost. There are times when sleep deprivation is unavoidable (for example, a new baby, studying for a test, a night training mission, or night ops), but you can engage in strategic napping before and after sleep loss to ensure that you don’t suffer the consequences of a big sleep debt. Read HPRC’s “Nap to be at your best mentally” to learn how to nap well.
Banks, S., & Dinges, D. F. (2007). Behavioral and physiological consequences of sleep restriction. Journal of Clinical Sleep Medicine 3(5), 519–528.