Light therapy is one of the treatment options for people who experience a type of depression known as Seasonal Affective Disorder (SAD). It's been administered since the 1980s and is considered a mainstay treatment for SAD. About 4 to 6% of adults in the U.S. experience SAD.
What is Seasonal Affective Disorder?
Seasonal Affective Disorder is a type of depression characterized by symptoms, like fatigue, mood changes, tiredness, and lethargy, brought about by seasonal changes. The symptoms tend to occur during the fall and winter months when there is less sunlight and usually improve with the arrival of spring.
Research has shown that SAD is more common in countries further away from the equator, as they have shorter, darker days in the winter. SAD is more than just the “winter blues,” and the symptoms can be distressing and overwhelming to the point that they interfere with daily activities. However, SAD can be treated. One common treatment method is light therapy.
What Causes Seasonal Affective Disorder (SAD)
To understand how light therapy works, it’s important to learn about the biological causes of Seasonal Affective Disorder. People with SAD typically have three potential biological causes that contribute to their depression during the winter months:
a) Irregular Production of Serotonin
People with SAD may have reduced production of the brain chemical serotonin. Serotonin helps regulate your mood, and the presence of sunlight can trigger your brain to create serotonin. When there's a lower level of sunlight due to shorter and darker days in the fall and winter seasons, your body may not receive the regular signals to produce serotonin. As a result, you may experience SAD, as low levels of serotonin are often linked to depression and other mood disorders.
b) Overproduction of Melatonin
Melatonin is a hormone that plays a key role in maintaining your sleep cycle. The body produces it when it gets dark, but those with SAD may produce too much melatonin, leading to increased sleepiness and feelings of lethargy and fatigue. This can cause an interruption of your internal body clock and circadian rhythm.
Serotonin and melatonin help the body maintain the daily rhythm of your sleep-wake cycle. Changes in the production levels of these two hormones may disrupt these rhythms. People with SAD can no longer adjust to seasonal changes in day length, impacting their behavior, mood, and sleep schedule.
c) Low Levels of Vitamin D
Vitamin D is believed to promote serotonin activity. People with SAD are likely to have lower Vitamin D levels due to less daylight and sun exposure during the winter.
How Light Therapy Works
A clinical study found that light therapy improved symptoms in 67% of patients, which was the same amount who saw improvement on the antidepressant fluoxetine, part of the SSRI class of drugs. SSRIs refer to Selective Serotonin Reuptake Inhibitors and are the most commonly prescribed antidepressants.
Light therapy is considered successful by most experts because it regulates serotonin and melatonin production. Research shows that light therapy can reduce serotonin transporter binding, leaving serotonin in the brain and resulting in happier, “feel-good” moods.
Most people experiencing Seasonal Affective Disorder start light therapy in the early fall and continue with treatment until spring. You may also notice symptoms of SAD during prolonged periods of rainy or cloudy weather during other seasons. It's important to speak to your doctor first to get to know more about how using a light box for depression can be effective.
During your light therapy session, place the light box on a table or desk. You should sit in front of it at the specified distance. The light from the light therapy lamp should enter your eyes indirectly. Remember not to look at the light box directly, as the bright light can cause eye damage. Follow your doctor’s guidelines and the manufacturer’s instructions at all times.
Time and consistency are key when using your light box for depression. You may want to place your light therapy products in your home or office, so you can go about various activities, like reading, writing, or working, while conducting light therapy. Whatever the case, make sure to keep to your therapy schedule, but don’t overdo it.
Light intensity is recorded in LUX, which measures the amount of light you receive. According to Mayo Clinic, the recommended light intensity for Seasonal Affective Disorder is 10,000 LUX at a distance of 16 to 24 inches (41 to 61 centimeters) from your face. It's usually prescribed early in the morning and not in the afternoon, as that could disrupt your normal sleep-wake pattern, making it harder to fall asleep at night. Your doctor can help you decide on a light therapy schedule that works for you.
Your light boxes should be made for bright light therapy or phototherapy. Don’t use a normal lamp, as you are trying to simulate the full spectrum of light found in sunlight.
Using your light box for depression involves daily prescribed sessions of about 20 to 30 minutes with a 10,000 LUX light box. With lower intensity light boxes, longer sessions may be required. When you begin using light therapy lamps, your first response will indicate if you need to adjust the intensity, brightness settings, or duration. Follow your doctor's recommendations, and check the manufacturer’s instructions.
If your symptoms don’t improve, you may need additional treatment. Consult your physician on other treatment options, such anti-depressants or psychotherapy.
Health Cautions To Take Note Of When Considering Light Boxes
Before beginning light therapy or using a light box, consult a doctor first. This is especially important if you have a condition that makes your skin sensitive to light, you take medications that increase sensitivity to sunlight (e.g., anti-inflammatories or certain antibiotics), you have eye problems, or you suffer from a condition that makes your eyes vulnerable to light damage. People with bipolar disorder diagnosis should also consult their doctors before starting light therapy, as using light boxes may trigger mania. Some of the common side effects of light therapy include headaches, nausea, and eye strain.
According to Mayo Clinic, light therapy boxes are designed to filter out harmful ultraviolet (UV) light; however, some don't. When looking for a light therapy lamp, consider one that emits as little UV light as possible. You can consult a dermatologist if you have concerns about light therapy and your skin. Tanning beds are not an alternative and can greatly increase your risk of skin cancer.
Keep these tips in mind, and ask your doctor if light therapy is right for you.