We’ve had a wave of unusually warm weather here over the past couple of weeks; the early spring flowers are in full bloom and the trees are starting to show their first green. It’s safe to say that spring has arrived. (Time to see if my wireless signal is strong enough out on the patio to work out there…) This article from Scientific American Mind talks about a possible biochemical basis for the physical manifestations of springtime in humans known collectively as spring fever. Although the phenomenon is not as obvious now as it was in earlier centuries, the number of human births shows a peaks in March, hinting at a peak of sexual activity in June (which is when luteinizing hormone production, linked to reproductive functioning in both sexes, also peaks). It’s not clear yet what causes this in humans; in other mammals, similar changes are triggered by the changing length of daylight.
There’s a little bit in the article about SAD (seasonal affective disorder) and how day length affects that. (Incidentally, I wrote this essay a year and a half ago that covers some research into the possible adaptive value of SAD.) I hadn’t realized that it’s the increase in morning daylight that is most important for driving off the winter blues; someone’s found that on the western edges of time zones, where the sun rises later, there’s more depression. Indiana is on the western edge of a time zone, and it’s always a big deal to me when, in late January, the sun here starts rising before 8am. The difference is mostly symbolic, but it matters to me to turn that particular corner. (This is one reason, by the way, that Daylight Saving Time (DST) makes less sense in Indiana; we tend to have darker mornings and lighter evenings anyway. There’s also a fundamental lunacy to DST that I will not go into here, but I’m generally willing to expound on the subject indefinitely for anyone who cares to listen.) Going clear back to an 8am sunrise when DST started in March this year was disheartening, to say the least. (See this article from the Los Angeles Times for more about DST and SAD.)