Yesterday we learned that women want to bang (but not marry!) wide-faced men. Today's chemistry lesson concerns seasonal sexiness changes. A study published on the Psychology of Human Sexuality blog shows that men get lustier in the winter months.

To figure this out, researchers surveyed 114 men every three months for one year. At each interval, the guys rated the attractiveness of their own girlfriends or wives and of female strangers in photos. Some of the photos showed women's faces only, some showed women's full bodies in bathing suits and some showed close-up shots of clothed breasts. Perceptions of women's faces didn't fluctuate throughout the year, but body shots were rated higher in the winter months. Men also gave their partners higher attractiveness ratings in the winter than in the summer.

No one is quite sure why — maybe winter layers make bare skin more exciting; maybe seasonal hormone changes are at play; maybe there's an underappreciated sexiness to the trapper hat. Despite all this alleged winter randiness, summer months tend to be when people say they have the most sex. In one recent study, August was the best month for sex and February the worst. Conception rates, however, reach their annual peak in December.