as for me, i gave it a shot. i feel tired. i feel irritable. and just not ready for the day. four hours is clearly not enough. and take a look at this simple reaction test. without a full night's sleep, i can't catch this pen at all. but jen living on four hours of sleep her entire life, never misses. a night owl, and an early bird. unfortunately you can't train yourself to be a short sleeper because it's a genetic thing. experts say you shouldn't try, because consistently being sleep deprived can lead to health problems like obesity and depression. mara york. >> and that brings us to our facebook question of the day. how much sleep do you need and what happens when you get less? >> all right, if you are awake enough to type, logon to wnnfans.com. share your sleep stories. i'd have to think these people are blessed. >> absolutely. you are definitely not a short sleeper, right? >> i can get by on six or seven