How Much Sleep Do You Really Need?

Yes, we usually heard that 8 hours sleep is good for us. According to this article, people who sleep between 6.5 and 8 hours live longer. It also gives me a surprising result, sleep longer than 8 hours is worse than 5 hours.

Quote from TIME

Studies show that people who sleep between 6.5 hr. and 7.5 hr. a night, as they report, live the longest. And people who sleep 8 hr. or more, or less than 6.5 hr., they don't live quite as long. There is just as much risk associated with sleeping too long as with sleeping too short. The big surprise is that long sleep seems to start at 8 hr. Sleeping 8.5 hr. might really be a little worse than sleeping 5 hr..