Biological changes are an important part of the teen-sleep picture, but they don't tell the whole story. Combined with these biological shifts are environmental and lifestyle factors that also can interfere with teens' sleep.

Are you curious -- and sometimes maybe a bit baffled -- by your dreams? Do you wake up with fragments of a dream fresh in your mind and wonder: Why did I dream that?

Athletes at all levels of play have access to a powerful tool to improve their performance, one that won't break any laws or put anyone's health at risk. What's this wonder drug? Sleep.

Are you a lark, someone who likes being up and active in the early morning? Or are you a night owl, someone who tends to wake later and perhaps gains energy and focus as the day progresses, someone who likes to work (and play) in the evening hours?

2012 was bursting with great sleep stories that revealed the power of sleep to enhance our health and well-being. Here are my picks for the sleep stories of 2012 -- along with suggestions for ways you can bring the benefits of the latest in sleep science to your everyday life.