sunlight exposure and health

Mind-Body-Mood Advisor: Bright Light Does More than Banish Depression

From trouble sleeping to overeating, the darker days of winter may be affecting your health more than you realize.

By Jeffrey Rossman, PhD

Mind-Body-Mood Advisor: Bright Light Does More than Banish Depression

Winter sunlight can be in short supply, but it's worth seeking out.

On a snowy, rainy, or cloudy day, it may not be practical or possible to get 30 minutes of exposure to bright sunlight. If you're sensitive to the effects of light deficiency, using a high-intensity light box can provide the boost you need. This is a convenient and reliable way to receive your daily dose of bright light when sunlight or outdoor time isn't available. To receive maximum benefit, the light fixture needs to provide 10,000 lux of light at a distance of two feet. That brightness is equivalent to being outside on a sunny day. The light does not need to be full-spectrum light. In fact, it should filter out potentially harmful ultraviolet rays.

Bright light improves sleep, as well, by helping to set your biological clock. When bright light comes in through the eyes, it signals the brain to be alert. And it triggers the pineal gland to delay the release of melatonin, the body’s sleepiness hormone. Those who have trouble falling asleep at bedtime or waking up in the morning can benefit from bright-light exposure in the morning to put their sleep/wake cycle back on track. Similarly, those who wake up too early are often helped by bright-light exposure in the late afternoon.

WHAT IT MEANS: Sunlight can have a powerful effect on our mood and our health. Perhaps because we see it almost every day, we take its effects for granted. It's on those days when we don't get much of it, though, that its importance is most apparent. Here are some ways to make sure you get the sunlight you need:

• Try to get at least 30 minutes of sunlight a day, even if you have to bundle up against the cold. Walking or jogging outside on a sunny day is an ideal way to combine exercise and light exposure. Of course there will be days when you can't get the outdoor time you need, but the more days you get some sun, the better you'll feel.

• Do not wear sunglasses when trying to receive the mood-boosting effects of sunlight. The light needs to be absorbed through your eyes. Don't leave your eyes unprotected in bright or direct sunlight, though, or in lots of sun reflecting off of snow and ice.

• Consider using a high-intensity light fixture or light box to receive the benefit of bright light when you can’t get sunlight for an extended period of time. There are many high-intensity lights available, ranging in price from $100 to $500. Some of the best models are in the low-$100 price range, so research your purchase carefully. In selecting a model, choose a fixture that has an adjustable stand. It is best if the light is just above eye level, shining down towards your eyes from a distance of 18 to 24 inches. You should not look directly into the light. You can read the newspaper, work on the computer, watch TV, eat breakfast, or jog on a treadmill, as long as the light is directly in front of you and shining slightly above eye level.

• Don’t use the lamp too close to your bedtime. Late-night exposure to bright light can energize you and make it difficult to get to sleep. As mentioned above, you may find that exposure in the early morning or late afternoon will help you adjust your sleep/wake cycle.

• Take vitamin D supplements if you are D deficient. Our bodies produce this vitamin upon exposure to sunlight, so a lack of sunlight can also mean a lack of vitamin D. A simple blood test ordered by your doctor can determine your vitamin D level. Recent research suggests that most people living in northern climates have low vitamin-D levels and can benefit from supplementation. Some foods contain vitamin D, but it can be hard to get enough from food sources alone. See our story on the newest vitamin D guidelines, and our vitamin D topic page.

• To learn more about the health- and mood-enhancing effects of bright light, visit the website of the Center for Environmental Therapeutics.


Published on: February 15, 2010

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It seems that I need to get more light from the sun now as well

Thanks for the great article! It seems that I need to get more light from the sun now as well. Since getting sunlight is free, there is no reason not to get our 30 minutes worth of sunlight a day. The benefits are plenty, and treatment is as easy as walking in the sun.

Lighting up my life

I live in the Catskill mountains, and days are shorter than when I lived on Long Island, but I have found ways to maximize the light, even when I can't go outside (24" on snow anyone?). I just repainted the window frames semi-gloss white and eliminated unnecessary drapes during the day. The extra light has really cheered up our winter-bound home! I still get outside periodically, as that snow won't shovel itself, so I get my sunlight and exercise whether I'm in the mood or not. It is nice, however, to sit on my exer-cycle in my sun-lit front room ;-)

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