I have to use two alarms to get up on time.
My main alarm clock is twenty minutes fast, and I set it an hour before I actually have to be up, because I sleep very deeply and I have to be able to hit the snooze button several times.
I also set the alarm on my cellphone, which is set to the correct time. Between the two of them, I can usually wake up on time.
My sleep schedule usually runs about like this:
Get home from work at 1230AM, stay up 'til about 3:30 or so, then go to bed. I don't fall asleep right away, but I'm usually out by about 4AM. I set my clock for 1PM, and I have to be up by 2PM to be at work on time.
So I get about 8-9 hours a night, unless I go to bed early.
I sleep with a sheet over my head for a variety of reasons, and that helps to block out the light while I'm daysleeping.
We see the world as "we" are, not as "it" is; because it is the "I" behind the "eye" that does the seeing.