^ you can sleep for less than 1 hours but in order to obtain GOOD rest you need 1 1/2 of sleep for you get your REM sleep. True story!!!! Humans sleep in 1 1/2 hour cycles, that's why a really long nap lasts around 3 hours!I love napsI always want longer than an hour though! My friend can put her head down for 20 mins and wake up feeling awesome but I feel groggy and more sleepy when I have so little.