Winter is here. For some people, that means the winter blues are also here.
Officially called seasonal affective disorder — with its descriptive acronym, SAD — winter blues can leave people feeling low on energy and muted to the normal joys of life. The disorder is a form of depression whose symptoms include feelings of hopelessness, worthlessness and guilt, and even suicidal thoughts. The defining feature of SAD is its seasonality: It generally doesn’t occur in the summer.
SAD can be treated with talk therapy and/or drugs; Wellbutrin and Prozac are approved by the Food and Drug Administration for this use, though doctors can prescribe other medications off-label.
In addition, SAD can be treated with light therapy. This involves sitting near a very bright (10,000 lux) broad-spectrum light for 30 minutes or so every morning.
Evidence for the use of light to treat SAD has been around for more than a decade, yet doctors were slow to adopt the practice, says Raymond Lam, a psychiatrist at the University of British Columbia in Vancouver. “One reason is that doctors are used to prescribing medicine,” he says.
In 2006, Lam embarked on a study to compare light therapy with the antidepressant Prozac in patients with severe SAD; he found that the treatments were equally good. If anything, the light therapy worked sooner — within a week — and caused fewer side effects, but over the eight-week trial, two-thirds of people in each group responded favorably to treatment.
A recent study found that even one episode of light treatment improved mood in SAD patients — at least on that day.
With three approaches to choose from — light, medicine and talk therapy — patient preference comes into play. For instance, light therapy takes time — a half-hour a day — and the cost of buying a light ($100 or more) may not be covered by insurance.
Some people use more than one approach. “In my clinical experience, many patients feel better with a combination of treatments,” says Teodor Postolache, a University of Maryland psychiatrist. Some address the problem by traveling south for the winter.
Why does light work? Several strands of evidence suggest that a deficit in light is the main trigger for SAD. The disorder is more common at higher latitudes, where winter daylight is limited. The timing of melatonin, a hormone involved in the sleep-wake cycle, is altered by the change of seasons and sometimes goes awry, Postolache says, and as a result, “SAD patients tend to extend their biological night.”
When light hits our eyes, it triggers neural activity that affects circadian rhythms, says Karen Roecklein, a psychologist at the University of Pittsburgh. So morning light exposure may help with the shift from sleep to wakefulness, from biological night to day.
Roecklein has found a biological difference between people with and without SAD. In healthy people, the eye’s sensitivity to light — measured by the pupillary response and presumably related to light’s ability to affect the biological clock — increases in wintertime. However, in people with SAD, the sensitivity to light is diminished.
While SAD may occur in 1 to 2 percent of the population, Lam says, milder versions of the ailment — the winter blahs — affect 10 to 15 percent of people. A mild case is more likely than full-blown SAD to be accompanied by physiological symptoms — oversleeping, overeating, carbohydrate craving and low energy — but less likely to prompt psychological symptoms such as intensely low mood.
