It’s April, and all the telltale signs are present: You can’t concentrate to save your life, you’ve got a rapidly blossoming crush on a coworker you didn’t look twice at all winter, and instead of hibernating like you have been for the past five months, you’re dying to get outside and soak up the sun and fresh air. When you do leave your office for lunch, you fantasize about taking the rest of the day off and wonder, Would anyone notice if I just didn’t go back there? Come to think of it, you feel this way every year around the same time. What’s the deal? You’ve got a classic case of spring fever, and you’re not the only one—millions of other people in the upper half of the Northern Hemisphere are experiencing the same symptoms you are.

The Body Electric
Spring fever isn’t just a state of mind; it’s a bona fide hormonal response to the stronger sunlight and longer days that the season brings about. As these factors become more pronounced, many scientists believe, our eyes let our brains know that spring has sprung. In turn, the pineal gland, located in the cerebrum (the expanded anterior portion of the brain where conscious mental processes occur), decreases its secretion of the hormone melatonin, which it’s been releasing in significantly greater quantities all winter. Because melatonin makes us sleepy and dampens our mood, we notice marked changes when our brains stop producing it so rapidly: good spirits, less desire to sleep, and reduced appetite—just in time to take advantage of those extra hours of daylight. As the Times (UK) summarized in April 2006, “Released from the chemical messages that make us withdraw in winter, the body feels energised, ready to hunt for food and to give birth.”

The combination of our waning appetite and our waxing wakefulness often leads to springtime weight loss, albeit relatively minor. Researchers at the University of Massachusetts who monitored the eating and exercise habits of six hundred people over a one-year period determined that the majority of the participants gained two pounds in the winter, both because they ate more carbohydrates and because they worked out less during that time. But as soon as spring began, the researchers found, the subjects’ caloric intake declined and their activity levels spiked. Maybe that explains why so many women love showing some skin come May or June: they’re not just enjoying the warmer temperatures, they’re also revealing slimmer figures.

Although some surveys indicate that a full 50 percent of residents of the northern latitudes of the United States experience palpable mood shifts related to the seasons, spring fever manifests itself most strongly in victims of seasonal affective disorder (SAD), most of whom are women. During the fall and winter months, SAD can be psychologically crippling for these individuals, so when their body chemistry alters with the arrival of spring, they “act as giddy as a puppet on a string,” clinical psychiatrist Normal Rosenthal told the New York Times in 1989.