Narrator: This is Science Today. What's the difference between one's actual sleep need versus their sleep habit? Allison Harvey, director of the Sleep and Psychological Disorders Laboratory at the University of California, Berkeley says it's often difficult to determine.
Harvey: We've just done a fairly big review of the existing literature on that topic and the methodologies to look at a question like that are very difficult because if you just ask people what's your sleep need? Then it's just going to confuse sleep need and sleep habit. You know, they might say, "oh, I only need six hours", but actually they need more than that. That's just their perception. And other people will be the opposite of that - they think they need nine hours when actually they probably do OK on eight hours. But from the literature that we reviewed, it did look like the adults it was about eight hours and recognizing that within that there are a lot of individual differences in sleep need. But eight hours is looking like it's the average.
Narrator: For Science Today, I'm Larissa Branin.