What time do you go to bed? What time do you usually get up?
Personally, I always go to bed around midnight. I try no later than 00 hours. I usually get up at 7.00 at the alarm clock. On weekends I can sleep until 9 o'clock in the morning. If I sleep less than 7 hours, then I walk like a sick person all day. So 4 hours of sleep is not for me.
The best thing is that early to bed and early to rise should be the timetable. Like half an hour here and thee is fine but something like sleeping at early morning and then waking by next day afternoon is something which should be avoided unless your work is schedule during those hours or only in case of emergency. Morning vibes and freshness is something different which i have found once started getting up early in the day rather than late.