Light therapy may hold promise as a treatment for bipolar disorder

According to a meta-analysis conducted by Dr. Raymond Lam — a professor in the department of psychiatry, director of the Mood Disorders Centre at the Djavad Mowafaghian Centre for Brain Health, and research scientist at the Vancouver Coastal Health Research Institute — and his colleagues, light therapy holds promise when it comes to the treatment of bipolar disorder. The Canadian Journal of Psychology recently published the study.

Seven studies conducted by various researchers showed that when it came to bipolar depression, light therapy (exposure to natural or artificial light for a certain amount of time), when used with a placebo (a harmless procedure prescribed to patients for psychological purposes rather than physiological) in two different experimental conditions, had a significantly higher positive impact than the placebo. These studies also showed that there were almost no side effects to using light therapy compared to using antidepressants as a treatment for bipolar depression.

According to Lam, there are two potential theories regarding how light therapy impacts the brain. The first theory suggests that the light that enters through the eyes has a positive impact on the suprachiasmatic nucleus (the ‘pacemaker’ of the brain). It is also a known fact that disturbances in this pacemaker can cause dysfunctional hormones, sleep patterns and cognition, along with other behaviours. But, it is unknown if regulating the pacemaker and its rhythms is the reason why light therapy works as an antidepressant.

The second theory suggests that light could possibly be acting on the neurotransmitters in the brain which play a role in mood and behaviour such as dopamine and serotonin, as there has been some evidence of light playing a role on these neurotransmitters in previous studies.

Bipolar disorder requires patients to take plenty of medication so it is important to find a non-medical treatment in order to limit negative drug interactions. However, before moving forward, there are also many logistics to be figured out such as what is the optimal dose, how long patients should be under the light, how bright should the light be and how long term the treatment should be.

“It is too early to say,” Lam said. “The studies used in the meta-analysis were small and generated some positive and negative results. We need more evidence to proceed to make this therapy a clinical treatment.”