Balance your daily activity
The National Sleep Foundation recommends 7 to 9 hours of sleep for adults, but a good night's sleep is not only a matter of quantity - sleep quality plays a major role, as well.
While you sleep, you go through cycles of sleep states. The first one is called light sleep and is followed by deep sleep and REM-sleep (a dream state).
A full sleep cycle lasts about 90 to 110 minutes and is normally repeated several times each night.