This information should not, however, be taken as a cause for alarm. I have a feeling we all get less sleep than we think, especially if the definition of sleep does not include activities such as watching the last 15 minutes of a movie in bed.
(What I want to know is whether they counted the time people spent half-awake after hitting the snooze bar for the first time but before actually getting out of bed.)
But if you'd be surprised by how much sleep you're actually getting, then that may be a good thing—it means you're getting enough sleep. Insomnia, they say, is largely a state of mind: If you're stressing about not getting enough sleep, then you've got a problem, regardless of whether the amount of sleep you're getting is actually enough to maintain good health.
If you're having trouble sleeping at night, I'm not going to dispense medical advice, because insomnia can be a serious problem. Then again, I started sleeping better —here I get a little plug in for Mellow Monk—when I switched from coffee to green tea.