Bright light therapy – also known as phototherapy – is used safely for many illnesses, but its most common application is to treat a kind of depression called seasonal affective disorder, or SAD. The efficacy of light therapy in treating seasonal affective disorder (SAD) can be linked to the fact that light therapy makes up for lost exposure to sunlight and resets the body’s internal clock. Light therapy might not work for everyone, but many people have found some relief from symptoms of SAD, other forms of depression, and sleep problems by using the machines themselves.
While it is now thought to mainly be used for treating SAD, light therapy is being used more often for treating other forms of depression and mood disorders, with promise. As noted above, light therapy can be used to treat many mental health conditions, and is frequently a first-recommendation therapy for people suffering from SAD. In fact, studies suggest that light therapy can also be an effective, rapid-acting therapy for non-seasonal forms of depression, including major depression (MDD). Light therapy has also been suggested in treating non-seasonal depression as well as other mental health mood disorders, including major depression, bipolar disorder, and postpartum depression.
For example, the BLT trial evaluated the effects of light therapy alone for SAD, a transdiagnostic condition which can impact patients with both unipolar and bipolar disorders, and suggested an early morning delivery of 30 minutes exposure using a 10,000-lux light intensity. These effects of light exposure on mood through regulation of circadian systems are not limited to patients with SAD, but are also present for patients with non-seasonal depression (both unipolar and bipolar), and the data that are available suggest that BLT is effective as antidepressant or mood stabilizer. BLT can also be beneficial to improve sleep quality, reduce alertness, abnormalities of circadian rhythms, such as sleep phase delayed syndrome, which are often associated with mood disorders, in order to prevent mood from early relapses and recurrence. Light can serve as a therapeutic mood stabilizer for patients with mood disorders in remission, stabilizing changes in sleep (such as insomnia or longer duration of naps) and circadian rhythms (such as nighttime chronotypes or delayed sleep phase).
Light therapy is generally more effective if done every day in the morning, because many individuals who have sleep issues related to their circadian rhythms or depression are those who have what researchers refer to as phase delayed. A sleep professional might begin by suggesting that the light exposure occur just before a patients normal spontaneous waking time. The specialists will usually suggest using a low-light environment at night, combined with bright light exposure during the morning, as sleep progresses. In a sunrise simulation, the person is exposed to the light for the last part of sleep.
When used consistently and in accordance with the advice of your physician, exposure to the light helps to re-set your circadian rhythm – a technical term for the timekeeper in your body. This technique — also called phototherapy — uses exposure to the light at appropriate times to help push back the patients biologic clock. By helping advance or delay your body’s circadian rhythms (body clock), phototherapy has been shown to improve many mental health conditions, including seasonal affective disorder (SAD), depression, bipolar disorder, attention-deficit hyperactivity disorder (ADHD), insomnia, and dementia.
Light therapy–or phototherapy, classically called heliotherapy–consists either of exposure to daylight or some equivalent form of light as a treatment for seasonal affective disorder (SAD), or of skin exposure to certain wavelengths of light using multichromatic polarizing light to treat a skin condition. Modern phototherapy lamps used for seasonal affective disorder and sleep disorders filter or do not emit UV light, and are considered safe and effective for their intended purposes, provided that photosensitive medications are not taken concurrently, and there is no existing eye disease. Light boxes are designed to be safe and effective, but are not approved or regulated by the Food and Drug Administration (FDA) to treat SAD, so it is important to know your options. Doctors and sleep specialists work with lights to create the most appropriate light treatment plan for their patients, including what times of the day the light box should be used, and how much of it for a period.
Light therapy can be used alone, especially for people who have milder symptoms, but it is also effective in combination with talk therapy, behavioral and/or lifestyle changes (such as exercise and good sleeping habits), and medications (such as antidepressants). The number of clinicians offering light therapy is increasing rapidly by the year, although compared with drug treatments or psychotherapy, this approach is still not widely used. Light therapy also starts working more quickly than most other forms of therapy, though therapeutic effects wane rapidly (within days) if a light box is not used regularly.
The benefits received from a brightening of light are short-term, and must be maintained through regular treatment. While further studies are needed, a small 2016 Psychogeriatric trial using bright light therapy showed improvements in sleep disruptions among patients with mild and moderate Alzheimer. A longer study tracking patients with SAD who received BLT both in a short-term (2-8 weeks) and a longer-term treatment period (fall and winter months over 3-6 years) found Bright Light Therapy achieved 75% clinical remission, as well as being just as effective as an antidepressant.
Bright light therapy is used for managing circadian rhythm disorders, such as delayed sleep phase syndrome (DSPS), a condition which moves normal sleeping patterns out of line with what is considered social norms. Although early studies that compared exposure of light to the eyes versus skin found light exposure to the eyes had a greater therapeutic effect in SAD patients, recent research indicates that circadian rhythms (the body’s biologic clock) may be affected by exposure of light to the back of the knee. Photodynamic therapy is a form of phototherapy using nontoxic light-sensitive compounds which are selectively exposed to light, at which point they become toxic to targeted malignant and other diseased cells.