Why am I always so tired and sluggish?

Sure my diet could be more refined. Could I become more active, yes. But I walk daily and am stimulated with work, yet I'm tired. I sleep from 10:30pm to 3am, get up for a half hour (don't know why and go back to sleep till 8am. Like right now, I could lay down (its noon). I'm 47 yo male. No health problems. I even stopped drinking. I don't smoke.