If you have bipolar disorder, depression or trouble sleeping, it may help to wear amber-tinted glasses at night, new research suggests. These orange shades block blue light, which the body uses to adjust the biological clock to control sleeping and many other functions.
Blue light is a major component of sunlight, and exposure to it in the morning signals that it’s time to wake up and also helps reset the body’s clock, which is why morning sun is so important for adjusting to jet lag. Likewise, darkness following sundown serves as a cue to sleep. This worked well for our ancestors whose primary source of light was the sun. But many modern-day electronic devices like phones, computers and televisions also emit blue light, and being exposed to these after dusk can confuse the body, interrupting sleep. This, in turn, can worsen and increase the risk of developing various mental illnesses.
Scientists have proposed that limiting exposure to blue light given off by electronics at night could help people sleep and help reset dysfunctional biological clocks, both of which are involved in disorders like manic depression.
In a small Norwegian study of 23 people hospitalized for bipolar disorder, scientists assigned 12 to wear “blue-blocking” amber glasses for one week, and 11 not to. Meanwhile, no changes were made to the patient’s medications.
The paper found an enormous difference between the two groups. Those wearing the amber-tinted glasses for only one week scored on average 14 points lower on a test used to measure mania known as the Young Mania Rating Scale. That’s more than twice what doctors consider to be a “clinically significant difference” and is a “remarkably high effect size,” according to a commentary accompanying the study, both of which were published in the journal Bipolar Disorders. Improvements were noticeable after only three nights of wearing the sunglasses.
“I was surprised by the magnitude of changes and the rapid onset of improvement,” says study first author Tone Henriksen, a researcher with the University of Bergen and Valen Hospital in Norway. Even drug treatments aren’t typically known to lead to such quick and significant turnarounds, she adds.
These are “knock-your-socks off results,” says Dr. James Phelps, a researcher and psychiatrist with Samaritan Health Services in Corvallis, Oregon, who wasn’t involved in the study. It's incredibly important to find new treatments as 20 percent of people with bipolar disorder commit suicide, the highest rate for any mental illness, he adds.
The paper builds on a growing body of research showing how important light is for controlling not only circadian rhythms but mood and many other aspects of physical and mental health. In the last couple decades, scientists discovered an entirely new type of receptor in the eye called intrinsically photo-responsive retinal ganglion cells.
These receptors detect only blue light and communicate with the hypothalamus, where the biological clock lives, explains Phelps. There are also connections with areas of the brain controlling the limbic system, involved in mood and emotions.
Though research on amber-tinted lenses has been limited, it has been shown that by blocking blue light, they trick the brain into thinking that it is dark. This allows the brain’s pineal gland to produce melatonin, an important hormone that helps promote sleep, Phelps explains.
It seems that several mental disorders are exacerbated by too much light, or an irregular cycle of light and dark, and this includes bipolar disorder.
In 2009 study in Chronobiology International, Phelps and a colleague found that 50 percent of 20 bipolar patients experiencing insomnia had significant improvements in sleep after wearing blue-blocking glasses. The majority of those who responded showed not just small but dramatic improvements.
Other studies have shown that exposing bipolar patients to actual darkness during the nighttime can have similar results; one 2005 paper found that putting 16 bipolar patients in darkened rooms for 14 hours per day greatly improved their manic symptoms. But actual darkness is much more difficult to obtain, and more disruptive to life.
Studies have also shown that light can act as an antidepressant. One study in JAMA Psychiatry in January found that subjecting patients to bright light therapy was as effective at improving (unipolar) depression as the antidepressant fluoxetine, but with fewer side effects. And exposure to light can also help prevent the depressive phase of bipolar disorder, says Francesco Benedetti, a psychiatrist at San Raffaele Hospital in Milan uninvolved in the present study.
There is still much to be learned about dark and light therapy, but some psychiatrists are ready to recommend these techniques and blue-blocking glasses. “When you have a low-risk, almost no-cost treatment with high efficacy, it's time to just use it,” Phelps says.
He adds that some of his colleagues would disagree with him, and he notes that it will be difficult to study the effect of the glasses once they are widely used. But people will find out about the glasses anyway via the internet, so “we might as well tell them what we know,” he adds.
One doctor in the field who didn’t want to publicly endorse a product recommends two models of amber safety glasses made by the Uvex company, which were originally designed to block bright light created by blue lasers used in welding and dentistry.
Light- and dark therapy, blue-blocking glasses, and interventions that shift around sleep and wake time can have huge impacts on bipolar disorder and depression, and Benedetti says that it’s time to start using so-called “chronotherapeutics” more widely.
“It’s time that these techniques enter the common, everyday clinical practice everywhere, as they do in several hospitals, mainly in Europe,” Benedetti says.