Less is more: Do you need eight hours of sleep to maintain good health? Scientists are not too sure. It's possible that sleeping too much, like eating too much, is bad for you. An American study on 1.1 million people shows that those who sleep for eight hours a day are 4-5 per cent more likely to die than those sleeping 5-6 hours. And those sleeping 9-10 hours a day have the highest mortality.

93% of Indians are sleep deprived.

Pay a sleep debt: It takes more than a night of extra sleep to pay off a sleep debt, especially if you slept only three to five hours--scientists say. But you recover faster from a week of poor sleep when it's preceded by nights with 10 hours of shuteye. So if you know you have a week of little sleep ahead, try loading up on sleep beforehand, not later.

Bedtime tales: Lack of sleep hits a woman harder and raises her risk of heart disease more than it does for a man, reports the journal Sleep. The study suggests that women require more sleep than men, but generally their sleep is of a higher quality, and less fragmented. Women also seem to use sleep medication more than men. For men, use of alcohol is more common, which shortens their sleeping time, though. Men tend to start losing deep, slow wave sleep much younger than women, which can make sleep lighter and more easily disturbed.

Dreams interpreted: To Freud, dreaming was a playground for the unconscious mind.To others, it helps the brain sort through emotional memories or current problems. Nowa report in Nature Neuroscience argues that dreams tune the mind for conscious awareness.We dream when the brain warms its circuits, anticipating the sights and sounds and emotions of waking. It explains why people forget so many dreams.

Should you nap?: We've heard that grabbing an hour's sleep during the day is as beneficial as a whole night in bed. But now experts from Harvard University, US, say, powernaps work only if the sleep is of the right quality. And a full night's sleep is still necessary for many vital body functions, even though a short sleep may boost learning and memory.