One scientist says you should have predictable sex. Huh?

If you feel like your sex life has gotten stale (read: Watch Letterman. Turn off lights. Get busy.) you'll love this!

Biologist Winnifred Cutler says regularly scheduled sex is good for you. Why? It keeps your reproductive system humming, regulating the hormones that make you fertile and, in turn, increases your sense of well being.

And men benefit too - bedding down on a regular schedule amps up his testosterone levels. And the more testosterone he has, the more he'll want to get busy.

Cutler recommends once a week romps. Weekly intercourse --but not less -- tunes the menstrual cycle to 29.5 days, which is ideal for a woman's sexual health.

But sadly, masturbation doesn't count. According to Cutler, it isn't the orgasm itself but the presence of another person that lets you reap these bedroom benefits, since feeling your guy's body alters your own body chemistry.

So if you're not boring if your sex life seems predictable - you're doing your body good!