You're tired. You could put your head down on a desk right now and fall asleep immediately. You went to bed late last night, had trouble falling asleep and woke up too early. And let's not kid ourselves: Tonight will be the same unless ... well, read on.

This is the classic not-so-shut-eye experience of many Americans who think they are sleep-deprived and possibly need pills or other treatment to fix their insomnia, teeth grinding, jet lag, restless or jerky legs, snoring, sleepwalking and so forth.

Reality is quite different.

For instance, insomnia is said to be the most common sleep disorder, but these dissatisfying sleep experiences only get in the way of daily activities for 10 percent of us, according to the National Institutes of Health. And in almost half of those cases, the real underlying problem is illness (often mental) or the effects of a substance, like coffee or medication. [Top 10 Spooky Sleep Disorders]

Learn five scientific findings to help you rest easier.

5 Things You Must Know About Sleep