Seasonal Affective Disorder
and Vitamin D
Seasonal affective disorder (SAD) was formally recognized by clinicians in the 1980s as a form of depression most commonly noticed in the winter. Research shows SAD to affect 4 to 6 percent of the general population with up to 75 percent of these individuals noted to be women. Experts relate SAD to a lack of sunlight alone, so with the onset of the winter months, days become shorter and people are exposed to less sunlight. With days becoming longer in early spring, symptoms of SAD subside. For instance, SAD occurs seven times more often in the cloudy state of Washington than in sunny Florida.
Symptoms of SAD may include grumpiness, sadness, irritability, increased appetite, weight gain, feelings of tiredness and lack of concentration. Even though we do not know the exact cause of SAD, studies have shown depressive symptoms to be related to issues within our circadian rhythm, melatonin levels and hypothalamus. The circadian rhythm, or body clock, is known to be disrupted by lack of sunlight and may result in depression. The hormone melatonin affects sleep and mood. It is thought that the hypothalamus needs sunlight in order to stimulate the aspect of the brain which controls sleep, mood and appetite, as well as the production of serotonin. Those with SAD often have lower levels of serotonin.
In 1999, researchers confirmed a direct link between exposure to sunlight and the production of vitamin D. In 2014, a research team, led by Alan Stewart, of the College of Education at the University of Georgia, published their findings in the journal Medical Hypotheses, which correlated taking a supplement of Vitamin D to decreased symptoms of SAD.
Vitamin D production occurs when the ultraviolet rays in sunlight strike the skin. Some foods, such as the flesh of fatty fish (salmon, tuna and mackerel) and fish liver oils contain a fair amount of vitamin D. In the U.S., fortified foods such as milk provide a good source of dietary vitamin D. Vitamin D has been shown to be required for a variety of healthy body functions, and lately has been a topic of interest in the treatment of SAD. A blood test is used to determine the level of vitamin D in the body.
Vitamin D supplementation in the form of D3 has been demonstrated to be effective in the treatment of SAD. Depending on a person’s lab values and symptoms, doses can range from 1,000 to 10,000 international units (IUs). Supplements are readily available and inexpensive. If an individual exhibits feelings of being down, irritable, moody or has trouble sleeping, they may have SAD. Their healthcare provider can check the vitamin D level and prescribe the recommended supplementation as needed.
Dr. Leta M. Vaughan, DNP, CNM, is a nurse practitioner with WomancarePC, which offers vitamin D testing, the Myriad myRisk Hereditary cancer test, and other screenings and lab panels. For an appointment, call 847-221-4800 or visit WomanCarePC.com.