I used to crave sleep but only be able to sleep 1 night every 2 days. It was horrible! Now I sleep every night in bursts of about 3 hours. I usually go to bed between 10 & 12 PM, sometimes at 8 PM, even 6 PM. I wake up every 2 to 3 hours, usually the first 2/3. It's not set in stone, I can wake up anytime, actually. If I'm lucky I'll sleep 4 hours but usually I am awake for the rest of the night until it gets to be 5/6 AM, then I finally sort of crash and sleep for a longer amount of time, until noon and most times lately even beyond noon. It's like I'm in a different time zone. It's very hard to wake me when I crash. I have tried getting up in the middle of the night, avoiding the crash sleeping that I do, but it upsets the whole balance because I'll start falling asleep at noon if I do. I do tend to fall asleep during the day too no matter what. I have gotten very tired in the last couple of years or so, I don't know where it comes from. Maybe it's the lack of a good sleeping pattern.