This is a story about love cycles (not the ferris wheels that moonstruck couples ride on the boardwalk). They are rhythms that link sexual behavior to hormones.

Biologist Winnifred Cutler found that regular sex is good for you. It orchestrates a woman's body biologically, regulating the flow of hormones that make it fertile and, in turn, increase well-being. It also props up testosterone levels in men.

Embrace once a week. Weekly intercourse—but not less—tunes the menstrual cycle to 29.5 days, optimal for fertility and general endocrine health.

Here's the tricky part: the findings mandate monogamy. Only committed relationships allow sex so regularly. If regular sex is not possible, then it's better to abstain altogether. That's because intermittent sex drives hormones wild, sending estrogen to lower lows (and higher highs) than the more moderate lows of celibacy. (Lows are responsible for bone loss, depression, and even heart disease.)

Banish the thought that you can keep yourself hormonally humming with your own hand. It isn't the orgasm but the presence of another person, preferably male, that does the trick. Men add chemicals that fire off nerve signals to the brain and alter endocrine patterns.

And by the way, riding the cycles of love is definitely an indoor sport.