I go to sleep between 1 and 2 AM usually. Try to get between six or seven hours, which seems to be just the right amount for me. When I sleep too much or too little I feel groggy and out of it, and it even seems to affect my physical strength negatively.
Used to pull all nighters all the time, sometimes going 24 to 48 hours with no sleep. Decided to put a stop to that when I read up on how horribly that affects brain chemistry, especially the part about how people who forego sleep regularly may be causing permanent damage.
Because what I did was done so willingly, it wasn't difficult for me to correct it. If I had a true sleeping disorder it definitely would not have been so simple.
regardless of the time you actually fall asleep you should be getting a bare MINIMUM of 6 hours to function "properly" to function at full capacity, you need 8 hours on average. this varies from person to person.
I get off work at 12am(0000 hours) and stay up till roughly 5-6am(0500-0600) giving me at least 8 hours of sleep if i wake up at 2pm(1400)