December 29, 2015

Feeling SAD this winter?


A new study shines a light on seasonal affective disorder, plus we offer mood-boosting tips to cope.

We’ve known for a while that lowered exposure to sunlight can affect our mood. Now a new Vanderbilt University study pinpoints the spot in the brain responsible for seasonal affective disorder, and theorizes that the time of year a person was born may affect whether he or she develops symptoms.

Study findings

Researchers need to do more work, but the study, conducted on mice, may give insight into how date of birth may enhance or reduce risk for wintertime depression in humans.

Biologists have found a small region in the midbrain called the dorsal raphe nucleus. It’s where many of the specialized neurons that control the brain’s levels of serotonin (an important neurotransmitter) are found. High concentrations of serotonin are associated with feelings of well-being and happiness; low levels are linked to depression. Thus, the dorsal raphe nucleus plays a role in regulating mood.

The researchers determined that mice born and raised in summer-light cycles exhibited less depression-like behavior than those born and raised in winter or even spring and fall. The summer mice had elevated levels of the neurotransmitters serotonin and norepinephrine. Additionally, when the summer-born mice were switched to exposure to winter light cycles, they continued to have relatively high serotonin levels.

“If such an effect occurs in humans, and is long-lasting, it could contribute to the season-of-birth modulation of SAD risk,” says Douglas McMahon, Ph.D., Vanderbilt’s Stevenson Chair in Biological Sciences, who supervised the study.

Symptoms and statistics

As many as 10 million Americans suffer from SAD, and based on national averages, thousands in Tennessee likely experience it. Women are four times as likely to have SAD than men. Symptoms usually appear between the ages of 18 and 30 but can affect people at any age. Those symptoms include fatigue, depression, difficulty concentrating, loss of sex drive, decreased physical activity, overeating and weight gain.

Natural tips for a brighter winter

Light therapy boxes and dawn simulators can help provide relief. Exercising outdoors in the daylight is not always an option, but even a walk on your lunch break will help boost your dose of natural light. Avoid alcohol and recreational drugs, which can exacerbate depression. Stick to a regular sleep-and-wake schedule. Increase your intake of vitamin D by taking a supplement, drinking fortified milk or eating fatty fish or egg yolks.

Questions? As always, talk to your doctor about possible treatment methods.