How many hours of sleep do you need to function properly? ——— it depends. Sometimes just 2 to 3 hours (usually if I'd been awake for 24 hours or longer and then went to sleep, or if I have an exciting new project going on), sometimes 8 hours. Lately, maybe more because my body's used to sleeping all the time. I wouldn't really know because I always get all the sleep I need plus a lot more.