During my adult life, I have alternated between getting way too little sleep (<4 hours) and way too much sleep (>8 hours). Call me strange but I have noticed that if I get sleep in 2 hour blocks, like 4 hours, 6 hours, 8 hours I feel well rested and refreshed, but if I sleep an odd number of hours I feel like I'm being robbed of sleep. I'm not sure if this is a mental thing or if it is my body's biological clock telling me to feel rested. Anyway, I've decided that 6 hours of sleep is the perfect amount for me to feel well rested and also to allow me to get more done in the day. I have been trying it out and it really does make me feel good and I don't even need to set my alarm as I tend to just wake up after sleeping 6 hours. Another nice benefit is that at night I actually feel tired when it is time to go to bed.