From: sai on
All of us would like to know how to sleep well so as to be at our best
when we get up. One of the important parameters involved in how to
sleep well is the time of going to sleep. Most of us have experienced
that we are not at our best in the morning when we go to sleep late.
Some of us are aware about the ill-effects of going to sleep late at
night at a physical and psychological level. However either due to
pressure of work or partying, more and more people are going to sleep
late at night.

More at : http://www.spiritualresearchfoundation.org/spiritualresearch/spiritualscience/how_to_sleep_well/sleeping_late.php