People with bipolar disorder may have interrupted circadian rhythms, which means their daily biological clock isn’t working well. A number of strategies may help to reset this internal clock and improve bipolar management, according to a 2012 research review published in Dialogues in Clinical Neuroscience. These include timed exposure to periods of light and darkness and a forced change in sleep times.
Also known as “bright light therapy” or “phototherapy,” light therapy treats SAD by exposure to artificial light, which mimics natural light lacking during late fall and winter. According to an article by Reuters Health, “[R]esearch suggests that bright light can affect levels of certain brain chemicals, like serotonin, thought to be involved in major depression. Light therapy also seems to zero in on the same brain structures that antidepressants target.”
Although light therapy for seasonal affective disorder (SAD) has been studied for some time now, more applications, including that of bipolar disorder, have been coming to the forefront. After a post on Psych Central had information about sleep and cognition improving with light therapy after brain injury, a researcher at Western Psychiatric Institute and Clinic (WPIC) in Pittsburgh is looking further into using light therapy to treat bipolar disorder.
Light therapy generally involves full-spectrum bright light exposure directly onto the eyes using a light source, such as a light box or a light visor. With a light box, the patient sits in front of the light while a visor allows for more mobility. This article offers an in-depth description of how light therapy works.
Study of Light Therapy for Major Depression
The largest study of light therapy for unipolar depression (that is, not bipolar depression) was done in 2016 and shows very positive results for those with depression.
This study found that light therapy actually outperformed fluoxetine (Prozac) for the treatment of depression and when light therapy was added to treatment with fluoxetine, remission rates were even better.
Dangers of Light Therapy
This is high-intensity light and so, anyone with any eye condition (such as macular degeneration) or any sensitivity to light (such as because of a specific medication) must be careful with it. See this page for the details on bright light exposure risk.
The risks in terms of bipolar depression appear to be a bit different from unipolar depression. The first thing you need to realize is that this type of bright light exposure works like an antidepressant, so all the risks of treatment of bipolar with antidepressants exist (Challenges of Bipolar Depression Treatment).
See here for more information on different kinds of light boxes.
Potential Advantages and Disadvantages
The advantages of light therapy include the fact that it is rather non-invasive with relatively few and minor side effects. Additionally, a significant number of people respond very quickly to this treatment.
The disadvantages of light therapy comprise the daily commitment of time and investment in the equipment. Some health care providers have light boxes available in their offices, but this necessitates a daily visit to the doctor. There are also companies that rent the equipment. However, insurance does not always cover the expenses associated with this type of treatment. Also, relapse of symptoms may occur after cessation of treatment.
Here is an article that takes a deep dive look into how light affects the brain.
Sleep and Rhythm
Everybody needs sleep, but people with bipolar disorder need to protect it. Sleep deprivation is associated with having manic symptoms. But perhaps even more important than sleep, or at least as important, is rhythm: the sleep needs to happen at the same time every day to keep your clock organized.
Darkness and Light
The evidence presented suggests that a person with bipolar disorder could minimize manic and depressive episodes by deliberately manage their exposure to light and darkness, especially darkness. The easiest way to arrange this would be to make sure a person is exposed to good quality darkness when asleep. Stopping any use of nightlights is critical. In one study, as little as 1/500th of midday sunlight (just 200 lux) was enough to disturb people’s melatonin, the sleep chemical in our brain).
Case Study – A patient with severe rapid-cycling bipolar disorder who stopped cycling entirely — with no medications — just by carefully using very regular darkness (first 14 hrs a night, then within a few weeks, to stay well, only 10 hrs. a night) showed promising improvement to his mental health.
Recent research has shown that one particular kind of light is the key to regulating the biological clock: blue light. Blue light is a powerful signal telling the brain “it’s morning time, wake up!”It is possible to significantly regulate bipolar cycling, and at least to go to sleep at night (without medications like zolpidem (Ambien), lorazepam (Ativan), trazodone, etc.), by avoiding blue light at night.
Dr. Dorothy Sit conducted a 2007 study in 2007 at WPIC, described in depth at this link.
- In a 2008 article on Psych Central, she said, “People with bipolar disorder are exquisitely sensitive to morning light, so this profound effect of morning treatment leading to mixed states is very informative and forces us to ask more questions … Did we introduce light too early and disrupt circadian rhythms and sleep patterns?
Dr. Dorothy Sit conducted another study in 2016.
- She was able to confirm the efficacy of bright light therapy for bipolar depression and discovered that light therapy at midday versus an inactive placebo comparator induced a potent antidepressant response in depressed bipolar patients.
“Dark Therapy”, in which complete darkness is used as a mood stabilizer in bipolar disorder, roughly the converse of light therapy for depression, has support in several preliminary studies. Although data are limited, darkness itself appears to organize and stabilize circadian rhythms. Yet insuring complete darkness from 6 p.m. to 8 a.m. the following morning, as used in several studies thus far, is highly impractical and not accepted by patients. However, recent data on the physiology of human circadian rhythm suggests that “virtual darkness” may be achievable by blocking blue wavelengths of light. A recently discovered retinal photoreceptor, whose fibers connect only to the biological clock region of the hypothalamus, has been shown to respond only to a narrow band of wavelengths around 450 nm. Amber-tinted safety glasses, which block transmission of these wavelengths, have already been shown to preserve normal nocturnal melatonin levels in a light environment which otherwise completely suppresses melatonin production. Therefore it may be possible to influence human circadian rhythms by using these lenses at night to blunt the impact of electrical light, particularly the blue light of ubiquitous television screens, by creating a “virtual darkness”. One way to investigate this would be to provide the lenses to patients with severe sleep disturbance of probable circadian origin. A preliminary case series herein demonstrates that some patients with bipolar disorder experience reduced sleep-onset latency with this approach, suggesting a circadian effect. If amber lenses can effectively simulate darkness, a broad range of conditions might respond to this inexpensive therapeutic tool: common forms of insomnia; sleep deprivation in nursing mothers; circadian rhythm disruption in shift workers; and perhaps even rapid cycling bipolar disorder, a difficult- to -treat variation of a common illness.
Here is a case study that explores the use of extended bed rest and darkness to treat rapid cycling in bipolar patients.
Origins of Light Therapy
Norman E. Rosenthal is a South African author, psychiatrist and scientist who in the 1980s first described winter depression or seasonal affective disorder (SAD), and pioneered the use of light therapy for its treatment.
In 1984, he coined the term and began studying the use of light therapy as a treatment. Rosenthal’s interest in studying the effects of the seasons on mood changes emerged when he emigrated from the mild climate of Johannesburg, South Africa, to the northeastern US. As a resident in the psychiatry program at the New York State Psychiatric Institute, he noticed that he was more energetic and productive during the long days of summer versus the shorter darker days of the winter.
In 1980, his team at NIMH admitted a patient with depression who had observed seasonal changes within himself and thought previous research regarding melatonin release at night may be able to help him. Rosenthal and his colleagues treated the patient with bright lights, which helped to successfully manage the depression. They conducted a formal follow-up study to confirm the success. The results were published in 1984, officially describing SAD and pioneering light therapy as an effective treatment method. The research on SAD and light therapy is inconclusive and in some ways controversial, as not all researchers agree with Rosenthal’s conclusions on the effect of light therapy and at what time of day the light should be administered.
Recently, Dr. Rosenthal has directed his research interests to Transcendental Meditation, leading him to use TM in the treatment of a diverse array of physical and psychological problems. This interest is reflected in his latest book, Transcendence: Healing and Transformation Through Transcendental Meditation (Tarcher Penguin, 2011).