How much sleep is enough? “The true answer is that it’s the amount each individual needs to have a spontaneous awakening that lets you feel refreshed and alert,” says sleep expert Michael H. Bonnet, PhD, professor of neurology, Wright State University. Studies in sleep labs show that for most people that means roughly seven to eight hours out of a 24-hour day, whether it’s all at once or includes a one-hour nap. Some people may need less (five or six hours) or more (nine) but they’re the exceptions to the rule.
“What’s crystal clear is that we do need adequate sleep to maintain health—and that truly disturbed sleep can be an early warning sign of a potential health problem, ranging from thyroid trouble to diabetes to depression. And while there are all sorts of theories about the role of sleep, from restoring cellular health to consolidating memories, laypeople don’t have to understand all the neurotransmitter connections to understand that they need to get enough sleep. “Trying to understand the neurochemistry of sleep,” laughs Dr. Bonnet, “Now that can keep you up all night!”
And, while it may be hard to believe, his research says that the average woman sleeps 20 minutes longer than the average man, says British sleep researcher Jim Horne, PhD, DSc, of Loughborough University. He theorizes that women “need more sleep because they use more different parts of their brains, on a day-to-day basis, than men do, and sleep’s major function is to allow the brain to recover.”
The time difference showed up “both in the sleep lab and in surveys. Age for age, there was a fairly consistent difference between how much women and men chose to sleep,” says Horne. The most common pattern was for women to go to sleep about 20 minutes earlier and wake up the same time as their partners. Professor Horne suspects that “either via multitasking, or continually making decisions about what to pay attention to and what not to, women, at least in the U.K., are using their brains in more challenging ways than men.”
Whether it’s coincidence or not, Dr. Horne also notes that “women’s brains seem to age more slowly than men’s.” So working your brain harder and giving it more rest in between may be the best life-long health recipe of all.