What kind of light is best?

Bright light is critical for the success of the Body Blues Program. It enhances your mood, reduces your food cravings, and gives you more energy. It even increases the blood flow to your brain, improving your memory and sharpening your thinking ability.

But there is a lot of confusion about which kind of light is best. Visitors to this site have asked: "Does it have to be natural light?" "Do full-spectrum lights such as the OTT light offer special advantages?" "Which do you recommend— ordinary bulbs or fluorescent lights?" "Can I get a "high" from a tanning bed?" "Does UV light influence your mood?" "Is there a best time of the day to get bright light?" "Does light have to come through your eyes in order to boost your mood?" "Can I get too much light?". Time for some answers.

First, the basics. Light boosts your mood in two fundamental and quite different ways: 1) by falling on your bare skin, or 2) by entering your eyes. Only one type of light influences your mood through skin exposure—ultraviolet or UV light. When UV light interacts with your skin, it triggers the formation of vitamin D. Vitamin D is far more than a bone builder. It has widespread influence throughout your body, including stimulating the production of feel-good brain chemicals such as serotonin and dopamine.

Unfortunately, UV light, whether from the sun or from artificial light sources, also promotes skin aging and increases your risk of skin cancer. Another way to get vitamin D is to drink fortified dairy products or take vitamin D supplements. Do the supplements offer the same mood benefits as the sun? Yes, according to researcher Allan Lansdowne who gave either placebos or vitamin D to volunteers who had low body stores of Vitamin D. At the end of the study, those who had been given the placebos had little change in mood. Meanwhile, those who had taken the vitamin D supplements felt noticeably better. In fact, many reported a better mood during the very first days of the study. (1)1The Landsdowne study is one of the reasons that we included Vitamin D in our LEVITY formula.

The light that enters your eyes has an even more immediate effect on your mood. Within 30 minutes of being in a very bright environment, you will feel more energetic and light-hearted. You will think more clearly and have a faster reaction time. After only a few days of these light treatments, you will be eating less and having fewer carbohydrate cravings.

Light offers you all these benefits because it modulates the production of certain hormones and brain chemicals. To be specific, bright light shuts down the production of melatonin, the nighttime sleep hormone. It also stimulates the production of serotonin, its energizing, daytime counterpart. In fact, within a few hours, the amount of serotonin in your brain will reflect the amount of light in your environment. More light = more serotonin = more energy, a better mood, and fewer carbohydrate cravings. In essence, light is the environmental cue that switches your body from a slumbering to an energized mode. If you don't get enough light during the day—and most women don't—you are likely to feel sluggish, irritable, hungry, and half-asleep all day long—a.k.a. the Body Blues!

How much light do you need to get rid of these unpleasant symptoms? More than you can get indoors with ordinary room lighting, which is about 50-200 lux. (Lux is one way to measure light levels.) The simplest way to get enough bright light is to spend an hour a day or more outdoors, where the light levels range from 1,000 to 50,000 lux or more.

But there may be times when you can't spend that much time outdoors. The weather may be miserable or your calendar too jam-packed. Or you may be kept indoors by an injury, physical handicap, or prolonged illness. An alternative is to purchase a light therapy device.

What kind of light therapy product works best? According to the research, you won't get much relief from "full-spectrum light bulbs," the kind you find in the supermarket or from widely advertised lamps such as the "Ott" light. You may find the color more appealing, but the light won't have much effect on your mood. (2)

For the most benefits, the light source either has to be very bright, 5,000 lux or more, or it has to be a very specific wavelength (such as the Apollo BLUEWAVE™, which is measured in photons/cm2). Brand new research shows that if you have light in a particular spectrum (around 460 nanometers, which is in the blue range) you will get benefits from much dimmer light.(3)

The majority of light therapy products on the market use fluorescent tubes. Compared with other sources of light, they're more energy efficient and less of a fire hazard. People who don't like the idea of fluorescent lights are probably thinking about the buzzing, flickering, unflattering light of years ago. Today's fluorescents have electronic components that have all but eliminated the annoying buzz and flicker. A more advanced type of light uses "light-emitting diodes" or LEDs and is very compact and light weight. A 5,000 lux phototherapy device that uses LEDs is as effective as a 10,000 lux device that uses fluorescent tubes. LEDs are also very compact, which has ushered in the new generation of ultra-light therapy devices.

No matter what kind of light you buy, make sure that it's UV-shielded. UV light increases your risk of cataracts and a more serious eye disorder called "macular degeneration." Tanning lights are a definite "no" because they emit a considerable amount of UV light and can increase your risk of certain skin cancers.

What time of day should you schedule your light session? Some, but not all, studies give a slight edge to morning light. But light at any time of the day has mood-enhancing, energizing effects. The only caveat is that you should not use bright light in the late evening hours because it will block your production of melatonin, depriving you of its calming, soothing, healing effects.

Finally, can you get too much light? Bright artificial light can trigger mania in some people with a condition called "bipolar disorder," formerly known as manic depression. And a small minority of healthy people report that getting an hour or more of very bright light can make them feel "jittery" or anxious or interfere with their sleep. (Especially if they get the bright light in the evening hours.) If you feel jittery when using a light box, simply shorten your exposure time until these symptoms go away. Of course, there are no known adverse reactions to natural outdoor light, —as long as you protect yourself from the UV rays!

As you begin to add more light to your life, keep in mind that the underlying goal is to recreate the natural outdoor environment—very bright in the daytime and blessedly dark at night. Turn off the bright lights in the late evening hours and switch to soothing, melatonin-enhancing dim light.

(You'll find three of our favorite light therapy devices in our Body Blues Store.)

1. Lansdowne, A. T., and S. C. Provost. "Vitamin D3 Enhances Mood in Healthy Subjects During Winter [in Process Citation]." Psychopharmacology (Berl) 135, no. 4 (1998): 319-23.

2. McColl, S. L., and J. A. Veitch. "Full-Spectrum Fluorescent Lighting: A Review of Its Effects on Physiology and Health." Psychol Med 31, no. 6 (2001): 949-64.

3. Warman, V. L., D. J. Dijk, et al. (2003). "Phase advancing human circadian rhythms with short wavelength light." Neurosci Lett 342(1-2): 37-40.