By Mary Carpenter
PREVIOUS MyLittleBird columns on the effects of light on wakefulness and mood have appeared in the spring, when the “ blue” morning light that wakes us up and makes some of us happier is increasing every day. So-called blue light inhibits the creation of melatonin in the brain so that the body knows it’s time to wake up, and early morning light contains more wavelengths in the blue portion of the spectrum than light at other hours. On dark winter mornings, late sunrise can interfere with circadian rhythms, causing melatonin levels to remain high for hours after waking—which in turn can cause fatigue and depression. These winter blues affect about 14 percent of Americans, with another 6 percent suffering the more severe seasonal affective disorder, or SAD. An estimated 10 to 20 percent of all cases of recurrent depression follow a seasonal pattern, according to Medical News Today.
Women are more likely to be affected than men, and January and February are the most difficult months. Besides fatigue and depression, symptoms of SAD include weight and appetite changes, difficulty concentrating, loss of interest in social activities and feelings of anxiety and irritability. In the past, the best solution has been “light therapy,” either heading outdoors as early as possible in the morning or using a light box like the Verilux, with light measuring 5,000 lux—compared to 500 lux at sunrise, the 10,000 lux of full daylight and up to 100,000 lux for direct sunlight.
But in a recent study, six weeks of light therapy for 30 to 60 minutes upon waking worked about the same as an alternative, cognitive behavior therapy (CBT) in twice-weekly sessions over the same period. CBT taught participants to challenge negative thoughts about dark winter months and resist behaviors like social isolation. The study at the University of Vermont, published in the American Journal of Psychiatry, followed 177 subjects over three years. During the second winter, those in both treatment groups initially experienced “large improvements,” but these dwindled after a while, according to the study’s leader psychology professor, Kelly Rohan. And in the third winter, 46 percent of those using light therapy had a recurrence of depression compared to 27 percent of those who had undergone CBT.
Rohan compares light therapy to blood pressure medication, a palliative treatment that requires you to keep using it to be effective, versus CBT, which is preventive: Once learned, the impact should last because CBT teaches skills, Rohan said. And with some research showing that thoughts and behaviors play a role in SAD, CBT gives patients a sense of control, Rohan told the Washington Post. “We can think outside of the light box. The good news is we can change our thoughts and behaviors.”
Giving CBT patients an even greater sense of control is CBT online. In recent literature reviews, some studies showed that people using internet-delivered CBT had equal or better outcomes than those using traditional in-person CBT, although study leaders caution against internet-based therapy for people with severe mental illness. An Australian study found that the free internet-based MoodGym CBT program, accompanied by brief face-to-face support from a psychologist, was an “effective treatment of depression” in a small sample of patients.
Among alternative weapons against SAD are the timing of exercise and diet. Because decreased body temperature signals the body that it’s time to sleep, 20 to 30 minutes of vigorous exercise in the morning can stave off sleepiness by raising the body temperature as much as two degrees for up to five hours. Meals high in protein also increase wakefulness, compared to high-carb meals, which make it easier to fall asleep—even when undesirable, such as at the opera. And getting protein from fatty fish like salmon can help you face winter like the Icelanders, who never seem to suffer from SAD —armed with high levels of omega-3 fats, which may stabilize mood and keep depression at bay, along with vitamin D, the “sunshine vitamin.”
But you might not want to abandon bright lights entirely, especially if body mass index (BMI) is a concern. In a Northwestern University study, for every hour that exposure to bright light was delayed, the subjects’ body mass index rose 1.28 points. Also, compared to CBT, there is nothing like the immediacy of that Verilux glow—or even better, of those first sunny springtime mornings some of us are already looking forward to.
—Mary Carpenter regularly reports on topical subjects in health and medicine.