You crawl in bed & close your eyes. However, it does not always happen that way! Physical & mental processes can effect sleep. Look at your lifestyle.

Are you hungry before bed?
Are you exercising too late in the day?
Is your bed being used for a multitude of other than sleep activities?

A good sleep benefits more than just your energy. Take a look here:

http://www.worldhealth.net/news/the_sleep_prescription_getting_a_good_ni