Autumn brings about many things: leaves on the ground, cooler temperatures, and of course, Halloween. But while many look forward to a reprieve from the summer months, the start of the season can introduce new challenges. Seasonal depression—commonly known as seasonal affective disorder (SAD)—is a temporary condition estimated to affect 10 million Americans each year.
Mariana Figueiro, PhD, Professor of Population Health Science and Policy at the Icahn School of Medicine at Mount Sinai, and Director of the Light and Health Research Center at Mount Sinai, explains the effects of SAD and how those who experience it can manage the disorder.
What are the symptoms of seasonal affective disorder, and what causes it?
Symptoms of seasonal affective disorder vary, but in general, it includes feeling down or depressed as well as experiencing a lack of interest and energy. People tend to be sleepier and tend to overeat, especially carbohydrates. And, as with any depressive episode, there could be suicidal thoughts. These depressive symptoms occur at specific times of the year, typically the fall and winter, and there is a full remission at other times of the year, such as the spring and summer.
Unfortunately, the cause of the disorder is still unclear, but there are some competing theories. One is that the start of autumn causes circadian rhythm disruption. Another is that the photoreceptors in the eye are not as sensitive to light, and another is serotonin reuptake dysfunction, which is an imbalance in serotonin levels. But the most prominent theory is that, due to the lack of or delay in getting morning light, the biological clock in the brain is out of phase with your natural light-dark patterns, affecting the timing of the sleep cycle. As such, your biological clock is telling you that it is 6:30 in the morning, but your watch is telling you differently. That mismatch can be the cause of seasonal depression.
Does the disorder only affect people who live in cities with long winters, or are people in warmer climates affected as well?
It tends to mostly affect people who live at higher latitudes, as these areas have less daylight availability in the winter months.
In the United States, higher latitude areas will be the northernmost states such as Alaska, Washington, Michigan, New York, and Maine. In the New York metropolitan area, we have about 15 hours of daylight at the height of summer but only about nine hours in the dead of winter. This contrast is starker in areas that are farther north. Barrow, Alaska—the northernmost city in our northernmost state—has 67 straight days of darkness in the winter.
Within high latitude populations, the prevalence of SAD varies between one and 10 percent. But it can happen at lower latitudes, it’s just less prevalent.
How can I recognize and manage SAD?
If you go to a physician, there are standardized questionnaires—such as the seasonal pattern assessment questionnaire—that you can take. But, in general, if year after year you begin to crave carbohydrates, lose energy, lose interest in things, overeat, and oversleep around October, that’s a good sign that you should seek a formal SAD diagnosis.
Once you consult a physician, they will discuss how you can manage the disorder. There are two common ways to treat SAD. One would be medication—typically an antidepressant or a selective serotonin reuptake inhibitor—that would be prescribed by a physician. The other is non-pharmacological: light therapy. Exposing yourself to light—be it morning, natural, or electric indoor light—will help resynchronize your biological clock so that it matches your local time. You can do this by adding more lights in the home, opening up your windows, and trying to be outside during daybreak. And if you work from home, try to sit facing a window. Making your environment brighter during the day will help get more light to the back of the eye, which is what you want in order to be an effective treatment for seasonal depression.
Has light therapy been used to treat other illnesses?
Yes, it has. The Light and Health Research Center at Mount Sinai has done a number of studies showing that—outside of treating seasonal depression—there is a definite benefit to exposing people to bright days and dim nights. For instance, in a study with Alzheimer’s disease patients, the lighting was changed in their nursing homes and assisted living facilities to simulate bright days and dim nights. The results were a very robust, positive impact on their sleep, mood, and behavior. In other applications, we worked with persons with mild cognitive impairment and sleep disturbance from mild traumatic brain injury to see how light therapy can help. And we have been working with breast cancer and myeloma transplant patients to see if delivering light therapy during a transplant or during chemotherapy will help to minimize fatigue and improve their sleep.
There are various applications. You can even use it to try to get your teenager to go to bed and wake up earlier. The addition of light can have many positive effects on life.