I'm not a doctor, but this sounds like a good way to get one's circadian rythms messed up. Thousands of years of evolution taught Man (and Woman) to adapt the rythms in his body to the revolutions of the earth around the sun. The first light in the morning "sets" the body's clock--and eating, growth, restoration, metablolism--even sex--revolve around the body clock and are affected by it and controlled by it.
I try to wake up with the sun and go to bed when my body tells me I'm sleepy. The sun, daylight, sleep, etc all control hormon balance, metabolism and lots of natural happenings in the body--and you can get them very messed up by playing with your sleep. Cancer, diabetes, cardiovascular disease, dementia, obesity, and lots of stuff is caused by sleep abnormality. I know because I have developed obstructive sleep apnea and I'm working as hard as I can to get back to normal, restorative sleep.