Personal Health: Steps for More, and Better, Sleep

In general, adults need at least seven hours of sleep, and being mindful of diet and exercise during the hours leading up to bedtime can help ensure a restful night.

Source: http://well.blogs.nytimes.com/2013/06/24/steps-for-more-and-better-sleep/?partner=rss&emc=rss

I found it found here as an example for more info