sleep (the natural state of rest during which you become unconscious): I suddenly woke from a deep sleep.
nap (a short sleep, usually during the day): I will take a nap after lunch.
doze (a light sleep, usually for a short time): I sat on the sofa and drifted into a doze.
snooze informal (a short period of light sleep, usually not in bed): This is a good place for a snooze.
forty winks informal (a short period of light sleep, usually not in bed): I pulled over to the side of the road to catch forty winks.
shut-eye informal (sleep): You look worn out! Go home and get some shuteye.