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Your monthly horoscope may point to astral elements as indicators of your sex life (or lack thereof), but what about seasonal influences? Here, a look at how weather changes can play a role in whether you feel like going on the prowl—or making a date with Ben & Jerry.

Spring and Summer

Summer lovin’ made a name for itself in Grease, and “spring fling” is in our vocabulary for the long-term. But in addition to its colloquial interpretations, hot-weather lust may have a scientific basis, too. Melanocyte Stimulating Hormone (MSH) has been linked to increased sex drive in women, and exposure to sunlight elevates the production and secretion of this substance. The reason: MSH regulates the synthesis of melanin, protective pigment that turns your skin a darker shade to protect it from harmful UV rays.

Serotonin, a feel-good neurotransmitter produced by the brain, may also be responsible for heightened mood and sex drive during spring and summer. Multiple studies have suggested that the production of serotonin is directly related to sunlight and that with increased luminosity comes increased serotonin levels.

But despite these hot-weather helpers, it’s possible that you may still get spring and summer blues (and the resulting lack of libido). Though rare, Reverse Seasonal Affective Disorder (SAD) is when warmer temperatures make a person feel cooped up instead of carefree. Characterized by anxiety, decreased appetite, insomnia, and irritability, the condition is triggered by longer days and too much heat and/or light. Those who experience Reverse SAD report feeling attacked by the sun and tend to go into Twilight mode—avoiding sunlight at all costs, taking frequent cold showers, and scampering from one air-conditioned environment to the next. To help patients escape from this ghostlike existence, doctors often prescribe therapy or medication.

Fall and Winter

Once fall hits, it’s no wonder your mojo goes into hiding—with less intense sunlight (and fewer hours of daytime), the sex-fueling serotonin from summer is present at lower levels. Replacing it is melatonin, serotonin’s Debbie Downer of a sister, which is produced in greater quantities when you’re in a dark environment.

This change in weather—and neurotransmitters—has a greater impact on some than others. But if you experience symptoms such as daytime fatigue and lethargy, excessive sleep, weight gain, sugar cravings, depression, and—oh, yeah—decreased interest in sex, you might have Seasonal Affective Disorder (SAD). To get your biological clock (and your sex life) back in order, make an appointment with a qualified mental health professional. As the first order of treatment, light therapy will likely be prescribed: According to the (NAMI), this method has a 50 to 80 percent success rate among patients. If you don’t respond to treatment, however, your doctor can suggest alternative options such as antidepressants or counseling. That said, expect your mood—and sex drive—to improve around March or April.