Every night I usually get around 5-7 hours of sleep, and I wake up at 6 AM to get to school and get home at around 3 PM. Some days, this isn't a problem, but others, I feel very tired when I get home so I decide to take a nap.

Now here's my problem. When I take a nap, it becomes a very deep sleep and usually ends up wasting my entire day, which then causes me to wake up feeling "depressed" since it's already 6-7 PM. This really doesn't affect my sleep though, I still am able to get into bed at the normal time and fall asleep in the same amount of time (Which is, in my opinion, insanely fast. Pretty much instant :P).

I go to bed at around 11 PM to Midnight. Sometimes later, but I think we all have those days occasionally (And rarely, in my case).

I've thought about maybe going to sleep earlier, but I feel like I don't get enough done in the day if I go to bed earlier. Sometimes it's because I took a nap from 3 to 6 PM, so I feel like I got nothing done during the day.

This isn't affecting my schoolwork at all, and I don't feel that tired during school, so my question is, why do my naps end up being so deep? Is it because I'm sleep deprived? I take naps in my bed under the covers, so this could be why....Maybe I should try taking a nap on a couch or in a chair? I really love naps, so my goal isn't to necessarily eliminate them. :P