Narrator: This is Science Today. It's well known getting a good night's sleep is good for your health. But just how much sleep should one get? David Claman, director of a University of California, San Francisco sleep clinic says that all depends on the individual.
Claman: There are people who many only need seven hours or may really be better off if they're getting nine hours. The truth is that what you really need is enough sleep that you can really feel rested during the next day and functional.
Narrator: Our internal clock, known as circadian rhythm, dictates our sleeping patterns.
Claman: Most people have a circadian rhythm that is approximately 24 hours. Now, there is some information studying people's natural rhythms, that if you are younger, you're more likely to have a rhythm that is a little bit longer than 24 hours. It's not true for everyone, but it can be generalized that it's more frequently true as you get older that your biological clock becomes slightly less than 24 hours.
Narrator: For Science Today, I'm Larissa Branin.