Don't sleep much and don't feel that tired? Maybe you have a case of hypomania.
Hypomania is usually described as a mood state or energy level that's elevated above normal, but not as extreme as mania. In other words, it is "hypo" - or less than - mania.
A decreased need for sleep is one of the hallmarks of both hypomania and mania. Some people sleep only a few hours a day, and yet they say they feel rested. At the same time, many creative people are energetic and while they are in the "flow" may need less sleep than normal. That does not necessarily mean they (or you) are hypomanic except in an informal, descriptive sense.
In addition to needing less sleep, symptoms may include:
If you truly have none of the other symptoms described above, then maybe you are one of the lucky people who can burn the midnight oil without troubling consequences.
But if you run into trouble because of sleeplessness - it might show up in periods of depressed mood, or relationships or work may suffer, or you may notice some of the other listed symptoms - you should consider consultation with a professional.