Can light therapies help with bipolar disorder?

Bipolar disorder is a mood disorder characterized by episodes of both depressed and elevated mood. It typically begins in the late teens to early 20s. During depressive episodes, people experience low mood, loss of self-confidence, hopelessness, and impaired sleep and appetite. Manic episodes are marked by an increase in energy, euphoric or irritable and rapidly changing mood, higher self-confidence, and decreased need for sleep. People may experience a mood episode every few years, or as frequently as several times a year.

Bipolar disorder can be treated with medications and psychotherapy. Certain chronotherapies — approaches designed to harness and normalize the body’s natural rhythms, such as light therapies — may help too, according to a recent systematic review of research.

Why might light therapies help?

Circadian rhythms, our natural 24-hour clocks, are disrupted in bipolar disorder. In addition, people with bipolar disorder seem to be more sensitive to light.

One way of treating bipolar disorder is to manipulate the circadian rhythm. This can be achieved with bright light therapy, dark therapy, sleep deprivation, and certain types of psychotherapy.

Bright light, dark light, and sleep deprivation

• Bright light therapy. Animals and humans experience seasonal and daily rhythms of body function and behavior that are influenced by light, among other environmental factors. Light activates the retina in the eye, resulting in a stimulus being transmitted from the eye to the hypothalamus in the brain. The hypothalamus helps regulate mood. In bright light therapy, a light box using fluorescent bulbs that emit 7,000 to 10,000 lux of UV-filtered bright white light is placed on a table at about eye level. (There are also head-mounted units or light visors.) Depending on the light output, time required is between 30 minutes and two hours a day. It’s reasonable to consider this treatment to help prevent or treat episodes of depression. It may be especially useful if a person has trouble tolerating medications.
• Dark therapy. Just as light therapy can improve mood, decreasing light can dampen manic symptoms. For treatment of mania, amber glasses that block blue light are worn in the evenings.
• Sleep deprivation. Onset of antidepressant effects can be rapid and striking. In total sleep deprivation, one is kept awake for 36 hours, all night and the following day. In partial sleep deprivation, one sleeps only four to five hours at night. Unfortunately, improvement in mood is short-lived. Switches to mania have been reported, so it should only be used in combination with a mood stabilizer.
• Though widely used, at this time there is little evidence to support the use of the supplement melatonin in bipolar disorder, according to the researchers.

Typically, light therapies are combined with other treatments for bipolar disorder, including those described below. Less often, they may be effective if used alone.

Additional approaches to changing circadian rhythms

Psychotherapy techniques can help people adjust dysregulated sleep patterns. Indeed, for typical insomnia, cognitive behavioral therapy, not medication, is the treatment of choice. Therapy works by controlling or eliminating negative thoughts and actions that keep one awake.

• Interpersonal and social rhythm therapy. This therapy is centered around the observation that a switch to depression or mania is often associated with a relationship difficulty that results in sleep deprivation. The therapist helps the patient work on regulating routine as well as the interpersonal problem.
• Cognitive behavioral therapy. Originally designed to treat major depression, this therapy aims to mitigate stressful life events that interact with negative cognitive styles to precipitate mania and depression.

These treatments can be combined with each other and used with medications, such as mood stabilizers and antipsychotic drugs. This may allow a person to take a lower dose of an antipsychotic drug than would otherwise be needed to manage symptoms. There are no absolute contraindications to bright light or dark therapies. However, using bright light therapy in the evening may worsen insomnia, and dark therapy should not be used in depression. Sleep deprivation is only used during the depressive phase because it can provoke manic symptoms or worsen them.