I have a friend a few years younger than me. We were recently at a bar talking about his girlfriend and my wife. After a time, he confided to me that in the past few weeks he has been having trouble getting it up and was very concerned that he would have to take erectile dysfunction meds for the rest of his life or that he was losing his edge. We are both in our early 40s and in good shape and health.
My answer to him was that he should not panic. It seems to me that as the weather gets colder, the days become shorter, and we set the clocks back, our bodies, which are much more attuned to nature than we are generally aware, prepare for winter and slow down. I noticed that my sleep patterns changed at the visible onset of winter. I've been less interested in sex and other physical activities. I also remember that in the spring, when the days get longer and the sun shines, I get really horny all of the time or at least I did last spring.
Are there any studies to support my thesis? Is any of this quantifiable?
Pretty much, yes. What a great question to get on a gloomy winter day just a few days shy of the solstice. Let us thank all the little gods and goddesses for the end of the %#@&*%@ darkness, with extraspecial gratitude reserved for Flora, Persephone, Maia, and anyone else who is usually depicted wreathed in posies and scattering petals through the newly verdant forest while the little animals frolic ... ahem. Why do I have spring fever when it isn't even spring?
I'm not sure if there has been any serious research done on humans and libido fluctuation through the seasons, but because the slightest fluctuations in reproductive capacity can cost high-stakes meat producers serious money, plenty of hormone-titer and testicle measurements have been done on bulls and boars and other large horned or tusky beasts, and yes, those characteristics do fluctuate with the seasons, and by quite a bit too. Mostly, though, males get all maleish during their breeding season, whenever that may be, but one of the most striking differences between ourselves and most of our animal cousins is our lack of an estrus cycle and corresponding male big-balls cycle. However ...
It's nice that I happened to mention little animals frolicking, because have I got a frolicking animals story for you: "Sex Ends as Seasons Shift and Kisspeptin Levels Plummet" (at www.eurekalert.org/pub_releases/2006-12/iu-sea122806.php). It concerns a neuropeptide most excellently named kisspeptin. Oh, and it's about Siberian hamsters. Kisspeptin triggers the release of the important reproductive hormones gonadotropin-releasing hormone and luteinizing hormone, without which we (and the hamsters) would not experience puberty, libido (in the hamsters at least), or conception. Hamsters placed in a winterlike environment with short days and low light immediately experience a drop in kisspeptin and with it the hamster equivalent of mojo workin'. Happily, though, the winterized hamsters were just as sensitive to kisspeptin as the summer hamsters were; as the article emphasizes,
"What is really striking is the disappearance of kisspeptin in animals experiencing winter-like days, yet the ability to respond to kisspeptin when we provide it," said Timothy Greives, lead author of the study. "These data show that the disappearance of kisspeptin in the brain is likely critical in turning off reproduction during winter."
So is kisspeptin supplementation the answer to your problem? Oh, I wish, but hormone feedback loops are way too serious and complicated to mess with when we don't know what we're doing, and in this case we truly haven't the faintest. Plus, seen any kisspeptin on the supplement shelves recently?