November 14, 2024
Karen Elshout/St. Louis Post-Dispatch/KRT
People who experience more sadness and fatigue in the fall and winter may have seasonal affective disorder, caused in part by a decrease in daylight. Using a light lamp that has certain specifications is an evidenced-based therapy. In the file photo above, Danny Clifton, sits in front of his SAD light in November 2005.
People who feel more fatigued, sad, irritable and hungry as the days darken from fall into winter may benefit from using a light box, also called a therapy lamp, according to health experts.
Seasonal affective disorder, also known as SAD, is a type of depression that occurs in the fall and winter when the cold sets in and hours of daylight diminish, usually easing up when spring arrives.
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About 10% to 20% of people get the "winter blues," mild depression from being cooped up indoors, according to the Cleveland Clinic. For about 5% of people, however, SAD is much more serious. It can last as much as 40% of the year, impairing how people function and think just like major depression, the American Psychiatric Association reports.
Although the causes of SAD are not entirely understood, research indicates that reduced daylight in the fall and winter may be a culprit, because people get vitamin D partially through sunlight, which has been linked to serotonin production. People with SAD have reduced levels of serotonin, a hormone involved in mood regulation, according to the National Institute of Mental Health. A lack of sunlight may cause the body to increase the production of melatonin, a chemical that affects sleep patterns and mood, causing people to feel more fatigued in the winter, according to the Cleveland Clinic.
One the most effective treatments for SAD is light therapy, often combined with antidepressants and talk therapy. Sitting in front of a lamp that filters out damaging ultraviolet rays but gives off bright light for 20 to 30 minutes every morning can help. Some people start light therapy in the fall in anticipation of SAD. To get the full benefits of light therapy, people need to do it every day, usually until spring, according to the American Psychiatric Association.
Research has shown that light therapy can be effective, not just for SAD, but also for major depression and postpartum depression.
"For both seasonal and nonseasonal depression, the effectiveness of light therapy is approximately the same as antidepressant medications, or popular forms of psychotherapy such as cognitive behavioral therapy," Dr. Richard S. Schwartz, associate professor of psychiatry at Harvard Medical School, said in an article published by Harvard Health.
Since SAD lamps are considered medical devices, people should consult a medical professional before using one. For instance, if a person has SAD and bipolar disorder, rapidly increasing the amount of time in front of a light box or using one for too long could increase the risk of manic symptoms, the Mayo Clinic says.
Light boxes have become increasingly popular. So many are on the market now that are not designed based on science, making it difficult to choose an effective one.
Wirecutter recommended these three light lamps in September after more than 30 hours of research: Carex Day-Light Classic Plus, Northern Light Technologies Boxelite and Verilux HappyLight Luxe.
The Center for Environmental Therapeutics recommends people consider these factors when selecting light lamps:
• Lamps should have an intensity of 10,000 lux illuminance at a comfortable sitting distance. This should be measured with a broad-field illuminometer. Narrow-field measurements do not replicate the wider field of vision, which includes darker areas in the periphery.
• The screen size should be at least 200 square inches. Larger screens are preferable because smaller sizes increase the chance that small head movement reduce the 10,000 lux dose. Large light boxes mounted on walls or overhead stands are too distant to deliver 10,000 lux.
• Fluorescent lamps should have diffusing screens that filters harmful ultraviolet rays. Question claims of UV protection unless the product specifies that a polycarbonate filter is used.
• White light is considered the standard. "Full spectrum" lamps and blue lamps with color temperatures higher than 5000 degrees Kelvin create more glare and are not more effective.
• To avoid glare, project the light box at a downward angle toward the eyes. The lamp needs to be raised off the surface. Those that are titled upward toward the eyes increase glare.
