Lighten Up

Most people feel better when the sun shines and natural light floods their home and workplace. But what happens when winter approaches and sunlight decreases? For some, the shortening days of autumn jumpstart seasonal affective disorder (SAD), a condition that can influence health and relationships.

Many scientists believe the brain’s biological clock slows as daylight decreases, causing the brain to produce less serotonin, a neurochemical affecting mood and behaviour. The effects go far beyond the occasional winter blues–they incapacitate some people.

The SAD State of Mind

Full-blown seasonal affective disorder affects nearly three percent of Canadians; another 10 to 15 percent experience milder forms. Women between the ages of 20 and 40 are most susceptible, although men, teenagers, and older people also suffer.

The Canadian Mental Health Association lists increased appetite, cravings for carbohydrate-rich foods, and chronic low energy or fatigue as common symptoms. Other characteristics include diminished sex drive, decreased concentration, irritability, withdrawal from social situations, joint pain, stomach problems, and heaviness in the arms and legs. Some people feel anxious, desolate, or hopeless–even suicidal in severe cases.

Light Therapy Helps

Light therapy, also called phototherapy, has a positive effect in 65 percent of SAD cases, reports Dr. Raymond W. Lam, a leading SAD researcher at the University of British Columbia. Following a review of more than 70 controlled studies published during the past 20 years, Lam concluded that daily exposure to bright, artificial light effectively regulates symptoms of tiredness, appetite, carbohydrate craving, and weight gain; but may be less effective in reducing symptoms of more severe depression, which require psychological counselling, medication, or both.

Symptoms usually improve after only two to four days of light therapy, but more severe cases may show improvement after up to four weeks. The timing, intensity, and duration of light therapy can be adjusted for optimum results, with most people finding that morning exposure works best.

Light therapy causes mild side effects such as nausea, headaches, eyestrain, edginess, or euphoria in 20 percent of people. These effects usually diminish over time or can be reduced by decreasing light intensity or exposure time. While there is no evidence that light therapy damages the eyes, people with ocular risk factors (retinal disease, diabetes, macular degeneration, or photosensitizing medications) should have a baseline eye exam before starting light therapy and continue periodic eye checkups. Also, because symptoms of SAD may have other medical causes, it is important to check with a health professional to rule out other health issues.

Types of Light Devices

Several types of light devices are available. Fluorescent light boxes are the most extensively tested and demonstrate the greatest evidence of effectiveness. A daily dose of 30 minutes of 10,000 lux (a standard light measurement) works well for most people. Lower doses require longer exposure.

Head-mounted light visors deliver less, but better directed, light. Dawn simulators, which gradually increase light levels in the user’s bedroom shortly before awakening, are convenient because they don’t require specific time to be set aside for use. However, preliminary research shows they may be less effective than light boxes.

Light devices are available in health food stores, medical supply stores, drugstores, and by mail order at prices ranging from $150 to $300. While not covered by provincial health plans, the cost may be covered under private health insurance companies’ extended health benefits, if a doctor recommends their use.

We can’t fast-forward through the winter months, but we can make the best of them. A daily dose of light therapy–along with proper eating and exercise–can help brighten short, dark days and take some of the SADness out of fall and winter.

Shine on...Safely

• Do place your light box on a table or counter and sit within the distance recommended by the manufacturer–usually between one and three metres.
• Don’t stare directly into the light; but keep your eyes open to get the full effect. You can read or eat during your treatment.
• Do make sure your light device has an ultraviolet filter.
• Do check that the light device is CSA approved for use in Canada (UL means approved for use in the US). Light therapy devices are not well regulated in Canada.
• Don’t try to make your own light device or use sunlamps, tanning lamps, or halogen lamps as light devices. They can harm your eyes.
• Do consult a health care professional if you are using a light device and your symptoms don’t improve or if they worsen.