Blue spectrum light can worsen two systems that are already fragile in people with mood disorders: sleep and circadian rhythms. Fortunately, there are simple solutions to correct this problem.
Evening light can disrupt mood in bipolar disorder. In short, blue spectrum light emitted by many digital devices suppresses melatonin, worsening two systems that are already fragile in people with mood disorders: sleep and circadian rhythms.1 There are simple solutions to correct this problem, and they may also help the 40% of Americans who’ve made screentime a part of their bedtime.2
Blue light blockers
The first step is to wear amber tinted glasses that block blue spectrum light in the evening. This approach was studied in a small randomized controlled-trial of inpatients with mania.1 Manic symptoms improved over 7 days with the blue-light blockers, and the effect size was large. The protocol for this Dark Therapy required patients to either wear the glasses or remain in a pitch-black dark room from 6:00 pm to 8:00 am. After they recovered, they were able to ease the routine to a later start time. Blue light blockers appear to have preventative benefits as well, and, it’s reasonable to wear them 1 to 2 hours before bedtime when symptoms are mild or prevention is the goal.
Which glasses work?
To work well, the glasses should block at least 90% of blue light, and most products don’t have that rigor. The Dark Therapy trial used glasses from lowbluelights.com (any pair will work from that site). Other studies have used the less expensive Uvex models, which also earned high marks in a Consumer Reports test. For under $10, there’s the Uvex Ultraspec 2000 model S0360X, which fits over regular glasses, and the Uvex Skyper model S1933X.
Blue blocking glasses are uncomfortable to sleep in, so a pitch-dark bedroom was part of the overnight pro
tocol in the Dark Therapy trial. Eliminating bedroom light may help depression as well as mania. Bedroom light as low as 5 lux (ie, a nightlight) has been linked to higher rates of depression, so pitch dark is the goal here.3 Ideas for darkening the bedroom include black-out curtains, eye masks, electrical tape over LEDs, towels or draft snakes under doors, or sleeping in the basement.
Sleeping with the TV on
What if patients find it difficult to sleep without the TV? Familiar voices are comforting, and patients often use TV to drown out the ruminative thoughts that would otherwise keep them up all night. Some TV sets allow the monitor to turn off, but for others the only solution is to shift to podcasts, radio, or music. Weightless, an ambient track by Marconi Union, was developed in conjunction with sleep researchers. In a small study, it produced greater relaxation and sleep than comparably mellow tunes.
Brain friendly night lights
Sometimes a pitch-dark bedroom is just not comfortable or safe. Fall risks and fears of the dark can affect anyone, although they are particularly common in the young and old. Theoretically, a low-blue nightlight could solve this problem, and at least one study used this approach.4 Blue-free nightlights, flashlights, and bulbs are available for $10 to $20 at lowbluelights.com or Amazon (Maxxima MLN-16 Amber LED Night Light, SCS Nite-Nite Light Bulb, and Lighting Science GoodNight Sleep).
The health risks of nocturnal blue light extend beyond sleep and mood. They include obesity, diabetes, cancer, cardiovascular and neurologic diseases, gastrointestinal ulcers, and adverse reproductive outcomes, according to a position statement from the American Medical Association.5 To avoid the fate of the cigarette industry, manufacturers of smartphones and tablets have added settings that lower blue light at designated times. For laptops, there are free apps that do this (f.lux for Windows or Candlelight by Oliver Denman for Mac). All this is well intentioned but, like cigarette filters, they should not be relied upon. They won’t make a serious dent in those health risks because much of the problem comes from energy efficient lighting.
Warnings and caveats
Many patients expect blue-light blocking glasses to cure their insomnia. Rather, it seems they protect the brain against some of the mental and physical consequences of not sleeping. In the Dark Therapy trial, patients who wore the blue-light blockers did not sleep more (they actually slept a little less!) although their sleep did become more regular.
While some patients give up too early, others go overboard. Amber glasses have a calming effect, causing some individuals to wear them to relax during the day. Wearing them before 6:00 pm, however, could cause depression by flipping the circadian rhythm in the wrong direction.
What to expect
The benefits of blue-light reduction has the best evidence for bipolar disorder, particularly for mania, mixed states, and rapid cycling.1,6,7 Can it work for unipolar depression as well? Epidemiologic and animal studies suggest so, but controlled trials are mixed. The one with positive results was small (N=27) and centered on postpartum depression, where nocturnal awakening is the norm. Women who used blue-light blockers and low–blue-light bulbs had greater improvements than those who used placebo glasses and bulbs.4 The study with negative results was also small (N=20) and included depressed patients with insomnia.8
A few studies have ventured into the general population, and the results are encouraging. Reducing blue light deepens sleep, promotes earlier bedtimes, and improves concentration the following day.2,9
Dr Aiken does not accept honoraria from pharmaceutical companies but receives honoraria from W.W. Norton & Co. for Bipolar, Not So Much, which he coauthored with James Phelps, MD.
1. Henriksen TE, Skrede S, Fasmer OB, et al. Blue-blocking glasses as additive treatment for mania: a randomized placebo-controlled trial. Bipolar Disord. 2016;18:221-232.
2. Heo JY, Kim K, Fava M, et al. Effects of smartphone use with and without blue light at night in healthy adults: a randomized, double-blind, cross-over, placebo-controlled comparison. J Psychiatr Res. 2017;87:61-70.
3. Obayashi K, Saeki K, Kurumatani N. Bedroom light exposure at night and the incidence of depressive symptoms: a longitudinal study of the heijo-kyo cohort. Am J Epidemiol. 2018;187:427-434.
4. Bennett S, Alpert M, Kubulins V, et al. Use of modified spectacles and light bulbs to block blue light at night may prevent postpartum depression. Med Hypotheses. 2009;73:251-253.
5. Lunn RM, Blask DE, Coogan AN, et al. Health consequences of electric lighting practices in the modern world: a report on the National Toxicology Program’s workshop on shift work at night, artificial light at night, and circadian disruption. Sci Total Environ. 2017;607-608:1073-1084.
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7. Phelps J. Dark therapy for bipolar disorder using amber lenses for blue light blockade. Med Hypotheses. 2008;70:224-229.
8. Esaki Y, Kitajima T, Takeuchi I, et al. Effect of blue-blocking glasses in major depressive disorder with sleep onset insomnia: a randomized, double-blind, placebo-controlled study. Chronobiol Int. 2017;34:753-761.
9. Shechter A, Kim EW, St-Onge MP, et al. Blocking nocturnal blue light for insomnia: A randomized controlled trial. J Psychiatr Res. 2018;96:196-202.