Every winter brings an increase in darkness caused by shorter days, often intensified by cloudier skies. Modern life steals even more light; for many people who work indoors, daytime feels more like a rumor than a fact during the colder months. It’s enough to make anyone SAD.
SAD, or seasonal affective disorder, is a mood disturbance caused by reduced exposure to sunlight. Like millions of others, Jane Vosk, 64, a retired teacher who lives in Seattle, would feel depressed, fatigued and withdrawn during the winter months. She would also crave carbohydrates, overeat and gain weight. Symptoms, which can start mild and worsen, may also include irritability, anxiety, apathy and even hopelessness.
What brightened Vosk’s life is phototherapy, in which a medical-grade lightbox provides mood-lifting light. Vosk got her first lightbox 25 years ago and says, “It changed my life.”
Out of Rhythm
Seasonal darkness can disrupt one’s circadian rhythm. Operating on roughly a 24-hour schedule, this body clock uses daylight to promote wakefulness in the morning and a hormone called melatonin to encourage sleepiness in the evening.
“When the morning sunlight first enters your eyes, it activates cells in the retina that tell the hypothalamus [a part of the brain that controls hormone production and distribution] to send a message to your pineal gland to stop making melatonin. Night’s darkness flips the melatonin switch back on,” explains Paul Desan, MD, PhD, of Yale-New Haven Hospital in New Haven, Connecticut.
Desan says the darker months trigger more melatonin production as well as reduced levels of serotonin, a neurotransmitter that contributes to feelings of well-being. This imbalance leads to the symptoms that mark SAD.
The farther north, the longer the winter nights, the more SAD occurs.
“Women are five times more likely to get it. We don’t know why, but it has something to do with hormones, because generally after age 55, the difference between the sexes equalizes,” says Alfred Lewy, MD, a psychiatrist and SAD specialist at Oregon Health & Science University in Portland. Genetics may also play a role.
There are different types of depression, so depressive symptoms should always send you to your healthcare practitioner for a full evaluation. If SAD is the diagnosis, light therapy is the way to go.
Phototherapy works by helping to adjust the timing of melatonin release and other bodily rhythms, thereby shifting the body clock to a healthier balance. “Excellent data confirms the effectiveness of medical-grade lightboxes, though they have yet to get FDA approval,” says Desan, who trusts any manufacturer who is a member of the Society for Light Treatment and Biological Rhythms.
The average lightbox is about 1 ½ by 2 feet (the future promises small, head-mounted ones), with cool fluorescent tubes and a clear cover that diffuses the light and blocks any minimal UV rays that are produced.
Lightbox effectiveness depends on several factors. First, the unit must be “bright enough to suppress melatonin production,” says Lewy; this requires a light intensity of about 10,000 lux. Sit within two feet of the box “and keep your eyes open, but don’t stare directly into the light,” he suggests.
Phototherapy treatment sessions should last for at least 15 minutes and can go for up to two hours. “Once a day does it, usually upon awakening. If you’re in that small group whose body clock responds better to evening light, then use it between 7 and 9 pm,” Lewy advises.
Lightbox benefits typically become noticeable within a couple of weeks. However, it took only two days for Vosk. “I was more cheerful and productive, instead of hibernating, and had more energy and more stable moods. But I had to use the lightbox every day, or two days later my symptoms returned,” she says.
Vosk has never experienced phototherapy side effects, which are short-lived and include reddened eyes, nausea, headaches, restlessness and irritability. Some antibiotics and anti-inflammatory drugs may negatively interact with phototherapy’s effects, as may supplemental melatonin and the herb St. John’s wort. Forego using a lightbox altogether if you have certain eye conditions (check with your practitioner).
Whether you use a lightbox or not, you should get outside more during the day if possible, along with keeping your curtains open and turning on more lights when inside. As with any type of mood disorder, proper diet, adequate exercise and regular stress management can help ease SAD.
Fighting Depression with D
Get a blood test for vitamin D; low levels have been linked with depression. Sunlight triggers production of this vitamin in the skin but a lightbox cannot, so you may need a supplement.
Torrey Smith, ND, a naturopath in Anchorage, Alaska, suggests taking 1,000-10,000 IU per day of vitamin D3, up to 50,000 per week, then retesting in two months. “People whose melatonin is easily shut off by low levels of light may be able to take enough vitamin D to alleviate some symptoms that are similar to SAD’s,” he says.
About three years ago, Vosk’s physician had her start taking 2,000 IU of vitamin D every other day. “And I discovered that I’m fine, amazingly enough. But I still get more depressed in the winter, so occasionally I use the lightbox,” she says.
No one knows how to prevent SAD. But with phototherapy, vitamin D and an anti-depressive lifestyle, winter’s dark months no longer need be a time of sadness.