Don’t Get SAD
Does winter make you blue? Do you feel increasingly less energetic and more lethargic as the cold, gray weather sets in and bright, cheery sunshine becomes a distant memory? You could be suffering from seasonal affective disorder (SAD), a recurring form of clinical depression that often crops up just as daylight becomes scarce and the darkness of long winter nights takes over.
For years, doctors have suspected that the onset of this form of depression must be related to light. Obviously, in winter, in the Northern Hemisphere, there’s less light on any given day. Between heavy clouds, bad weather, and shorter days, some of us may go for days at a stretch without ever seeing pure daylight, or feeling the weak sun on our faces. Some SAD patients find they can get significant relief by basking in artificial lamp-light, which simulates the full spectrum of sunlight.
Doctors theorize that this light affects the brain by stimulating the pineal gland (sometimes called the “third eye”). The pineal gland produces the antioxidant sleep-promoting hormone, melatonin, in response to complete darkness, so we know that although it’s buried in the skull, it still reacts to light and dark.
But sunlight also drives the production of another important hormone: vitamin D. Now researchers believe they’ve discovered a link between declining sunlight and falling vitamin D levels—and the onset of SAD.
It’s not too difficult to imagine the relationship among these factors. The brain messenger chemicals, serotonin and dopamine, which play a crucial role in maintaining mood, are generated in the brain with the help of vitamin D. For some people, falling vitamin D levels caused by fading sunlight may explain declining levels of these crucial brain chemicals. This drop could easily result in depression. Researchers note that studies have documented that depressed people often have abnormally low levels of vitamin D.
"What we know now is that there are strong indications that maintaining adequate levels of vitamin D are also important for good mental health," said Michael Kimlin, of Queensland University of Technology, in Australia. "A few minutes of sunlight exposure each day should be enough for most people to maintain an adequate vitamin D status." Barring that, it might be prudent to consider taking a vitamin D3 supplement to combat SAD.
Alan E. Stewart, Kathryn A. Roecklein, Susan Tanner, Michael G. Kimlin. Possible contributions of skin pigmentation and vitamin D in a polyfactorial model of seasonal affective disorder. Medical Hypotheses, 2014; 83 (5): 517 DOI: 10.1016/j.mehy.2014.09.010