What Color Light Is Best for Depression?

Blue light therapy can be used to treat depression

Full spectrum bright fluorescent light that simulates the wavelengths of natural daylight is the most effective light therapy for certain types of depression. It is part of the first line treatment for a type of depression that occurs with change in seasons, known as seasonal affective disorder (SAD), but also useful for a few other conditions that affect mood.

Research indicates that blue light is superior to other lights in the spectrum for treating depression. Studies show that blue light can be used at a specific wavelength and frequency at less intensity than full spectrum bright light to achieve the same kind of effects.

The success with bright light in mood improvement spurred research on the efficacy of other lights in the spectrum, in improving symptoms of depression. The effects of green light have also been studied, but green light has not shown evidence of having any antidepressant effects.

Light therapy, also known as phototherapy, involves the use of artificial bright light or blue light to improve mood and reduce depression symptoms. The blue light used in light therapy for depression is filtered to block ultraviolet (UV) rays and not to be confused with the UV blue light therapy used to treat certain skin conditions such as psoriasis.

Light therapy for depression involves the use of artificial lamps to create bright daylight conditions for 30 to 60 minutes immediately upon waking. The therapy typically has to be followed throughout the period of risk for depression, usually from September to April.

Light therapy is primarily used to treat seasonal affective disorder (SAD), also known as “winter blues.” SAD is a form of depression that has worsening symptoms during the fall and winter months. SAD does occur for some people during spring/summer but is more common in fall/winter.

Seasonal affective disorder tends to occur more often in women and accounts for approximately 10% of all major depressive disorders. SAD usually starts in late teens and disappears with menopause. SAD is more common in the far northern and southern latitudes where day lengths in summer and winter vary to a great degree.

SAD is thought to be caused by chemical imbalances in the brain because of shorter daylight hours and reduced sunlight in the winter months. The body’s normal circadian rhythm, the 24-hour internal clock that regulates the sleep-wake cycle, is disrupted, leading to depressed mood and lethargy.

Other conditions for which light therapy can be useful include:

• Depression that is not seasonal
• Jetlag
• Sleep disorders
• Adjusting to night shift work
• Dementia

Exposure to an hour of bright light in the morning helps maintain the body’s normal circadian rhythm. When eyes sense bright light in the morning they send signals to the brain to reduce the levels of melatonin. Melatonin is a chemical messenger (neurotransmitter) in the brain that regulates the body’s circadian rhythm and energy metabolism. 

Melatonin level normally rises in the evening, which helps us sleep better, and goes down in the morning, which keeps us alert and energetic during the day. In people with SAD, melatonin levels continue to remain high in the morning, which leads to depression, anxiety and lack of energy during the day and sleep problems in the night.

By suppressing melatonin levels in the morning, light therapy increases energy levels and alertness during the day, and improves night sleep, both of which contribute to a person’s state of wellbeing and happiness. Bright light is believed to also boost the level of serotonin, another hormone that regulates mood and emotions.

The light intensity is measured in lux (one lumen per square meter) and you will need to use a 10,000 lux bright light, although blue light boxes may come with lower lux. It is not sufficient to expose only your skin to the light, your eyes must be open and indirectly exposed to the light, but you must not look directly at the light.

You may be required to spend about 30 to 60 minutes every day in front of the light, typically within 24 inches from the light, throughout the period that you are at risk for developing depression. You can set the light on a table so that you can work, eat, read or be occupied otherwise during the therapy.

It is best to first discuss with your doctor if light therapy will be useful for you and the type of device that will best suit your needs. Several types of light therapy devices are available over the counter, which can be used at home.

Light therapy is a safe and effective treatment with few side effects. Benefits of light therapy include:

• Noninvasive and easy to do
• Milder and fewer side effects than medications
• Can reduce or eliminate the need for antidepressants

Light therapy is generally a safe treatment for most people and the few side effects that do arise are mild and do not last long. Light therapy, however, is not regulated or approved by FDA for seasonal affective disorder.

People who have certain conditions or take medications that make the eyes or skin sensitive, and people with bipolar disorder need to exercise caution with light therapy. Side effects of light therapy include:

• Headache
• Eye strain
• Nausea
• Irritability or agitation
• Mania or hyperactivity in people with bipolar disorder