Getting enough sleep and sleeping at the right time of night is important for your physical, mental and emotional health. Your body needs time to repair itself and your mind needs time to assimilate and process all the happenings from the day. Things like alcohol and sleep aids can actually interfere with this by affecting the quality of your sleep.
It's also important to develop healthy pre-sleep habits like:
Don't watch the news or disturbing television shows or videos right before going to bed. Better yet turn the television off and read a book or listen to relaxing music. Wayne Dyer used to say that whatever you are thinking about right before you fall asleep is what you will "marinate" in all night.
Don't wait until you get into bed to figure out your to do list for the next day. Prepare for the next day before getting into bed.
Do take a break from electronics 1-2 hours before bed.
Do give yourself a dark, quiet and cool place to sleep.
Do think peaceful, calming thoughts once you are in bed. Leave the stress and worries for the next day.
For more tips you can check out this article, Relaxation Techniques for Sleep.