Light Therapy and Seasonal Affective Disorder

The abbreviation for seasonal affective disorder is SAD, which is very fitting of the condition, which can make you feel very sad, indeed. Seasonal affective disorder is a type of depression that comes and goes with the seasons. Most commonly, people with SAD experience especially severe symptoms during the winter months, which is why SAD is often referred to as “winter depression.” However, there are some people with SAD who have more severe symptoms during summer than during winter. 

Symptoms of SAD include persistent low affect and mood, loss of interest in otherwise enjoyable activities, feelings of lethargy, despair, and worthlessness, and increased duration of sleep. Some people also have greater cravings for carbohydrates and gain weight. These symptoms are very similar to the commonly known, major symptoms of clinical depression. For some individuals, SAD can be debilitating. People with debilitating SAD should evaluated by a health professional for treatment. 

The exact causes of SAD are unknown, but there is believed to be a link between less exposure to sunlight during shorter days in autumn and winter days and symptoms of SAD. One hypothesis is that reduced exposure to sunlight affects the hypothalamus and prevents it from working properly. This in turn may lead to increased melatonin production, which can make one more sleepy, decreased serotonin production, which is linked to decreased affect, and disruption of circadian rhythm, or the body’s internal clock. Most organisms, humans included, depend on sunlight to regulate their internal clocks so they can eat, sleep, and perform various tasks, at regular intervals. However, with reduced exposure to sunlight, these intervals will be irregular. There is some evidence showing that some individuals have genetic predispositions that make them more inclined to suffer from SAD. Data shows that rates of SAD tend to be higher in regions with lower sunlight exposure, and lower for areas with long, sunny days.

There are many treatments for SAD suited to the patient’s lifestyle, such as talking therapy, antidepressants, lifestyle changes, and light therapy. Light therapy specifically, has been gaining attention for its seemingly unconventional approach to SAD, as well as other conditions such as depression, jet lag, and sleep disorders. During light therapy, patients sit, or work, near a light therapy box, which is meant to emit light that mimics sunlight. This in turn artificially extends the photoperiod, or light exposure an organism gets in a day, essentially making the day longer. Scientists have been studying the results of light therapy for several decades, and evidence shows that effects of light therapy are comparable to that of antidepressants such as fluoxetine. Light therapy is an efficacious treatment for SAD because it is as effective as common antidepressants while having fewer side effects. The most common side effect for light therapy is insomnia, with few instances of hypomania and mania. On the other hand, common side effects of antidepressants include nausea, fatigue, drowsiness, blurred vision, constipation, and a number of other issues. 

If you or your loved ones are suffering from episodes of depression-like symptoms that seem to come and go with the seasons, a visit to your general physician, and a look into light therapy, may be wise. 

References:

https://www.nhs.uk/conditions/seasonal-affective-disorder-sad/

https://www.medscape.org/viewarticle/550845

https://www.mayoclinic.org/tests-procedures/light-therapy/about/pac-20384604