"Sleep is the new sex," said Jackie Clune in Britain's Daily Mail. Modern humans think and talk about sex all the time, but in a recent survey 80 percent of Britons said they "would choose a good night's sleep over a night of passion." Even men said they were usually too tired "to be bothered with a fumble when the lights go out."

Sleep isn't sexy, said Brooke Burke in Modern Mom, but it's amazing what a good snooze can do for a girl. Like most people juggling career and kids, I'm exhausted, and sleep deprivation can hamper your sex drive, metabolism, memory, and many other things. "No wonder I can't find anything, I'm grumpy," and "my sex life isn't what it used to be."

This is a chicken-and-egg problem, said gossip blog The Frisky. Sex increases blood circulation, and that's just one of the health benefits. Hormones released during sex can soothe aches and pains, and a 2002 study found that women exposed to sperm through unprotected sex reported less depression than those who used condoms or abstained from sex. If you're still not sold—"sex helps you sleep better."