Using Light to Improve Sleep and Depression
Blue-blocking glasses
At the 2018 meeting of the North Carolina Psychiatric Association, researcher Chris Aiken described the phenomenon of sleep inertia, when people are awakened from deep sleep by an alarm, rather than waking at the end of a sleep cycle, and are groggy for 15 minutes. Depressed people may stay groggy for 4 hours. A dawn simulator may help. These lights turn on gradually over the course of 30 to 60 minutes, reaching 250 lux while the patient is still asleep. Dawn simulators have worked in eight out of ten controlled clinical trials to help people with seasonal affective disorder, adolescents, and normal adults wake up more easily. They range in cost from $25 to $90 and some brands include PER2LED or LightenUp. Aiken says dawn simulators can improve depression, sleep quality, and cognition.
Evening and nighttime light: Bright lights and blue light, like the light that comes from electronic screens, can shut down the body’s secretion of melatonin, making people awake and alert in the evening when they should be getting sleepy. Dim light or glasses that filter out blue light allow increases in melatonin secretion in the evening, while bright light suppresses it. Missing this early melatonin pulse creates “night owls” who have delayed sleep onset.
Because light still reaches our eyes through our eyelids as we sleep, even low-level light during the night impairs sleep, cognition, and learning, and increases the risk of depression by a hazard ratio of 1.8 (about double the risk). A 2017 study by Kenji Obayashi in the American Journal of Epidemiology found that bedroom light above 5 lux elevated rates of depression in older adults after two years of followup. Living room light averaged around 50 lux and increased depression further.
A slide from Aiken’s presentation shows comparative levels of light
The treatment is turning off TVs, electronic screens, and cellphones in the evening or wearing blue-blocking glasses, which can be found for less than $10. Blue-blocking glasses can increase calmness and reduce anxiety, and even are effective in treating mania. Then, during sleep, wear an eye mask or get light-blocking blinds or curtains for windows. For a complete blackout, use blackout curtains, aluminum foil over windows, electric tape over LED lights, or try sleeping in the basement.
Aiken suggests that to re-instate healthy sleep patterns, people should institute virtual darkness from 6pm to 8am, including wearing blue-blocking glasses when out of bed. Then they should institute total darkness or wear an eye mask when in bed. When symptoms improve, this routine can gradually be shifted to begin later in the evening, such as two hours before bedtime.
Blue light filters are also available for smartphones and tablets including Apple Nightshift mode, Kindle BlueShade, and Android Twilight and Blue Light Filter.
Glasses that filter out blue light include Uvex Ultraspec 2000, 50360X ($7 on Amazon) and Uvex Skyper 351933X ($7-10 on Amazon). The website lowbluelights.com sells blue-blocking glasses from $45 and a variety of other blue-free lighting products such as lightbulbs and flashlights.
Bright light therapy for unipolar and bipolar depression: 30 minutes of bright light (7,500 to 10,000 lux) in the morning can help treat depression in unipolar and bipolar disorder and seasonal affective disorder. The effects usually take 3 to 7 days to set in, but they only last while a patient continues using the bright light in the morning. Researcher Dorothy K. Sit and colleagues found that bright light therapy in the morning sometimes caused hypomanic reactions in people with bipolar disorder, and reported in a 2018 article in the American Journal of Psychiatry that midday light therapy (from noon to 2:30pm) was also effective without this unwanted effect. However, a 2018 article by Ne?e Yorguner Küpeli and colleagues in the journal Psychiatry Research suggested that a half hour of morning light for two weeks was sufficient to bring about improvement in 81% of patients with bipolar disorder and did not cause serious side effects.
Melatonin regimen for sleep onset delay: Melatonin can be used to treat severe night-owls with a very late onset of sleep (for example, going to bed at 2 or 3am and sleeping late into the morning). Melatonin can help with sleep onset to some extent when used at bedtime, but in those with an extreme phase shift, researcher Alfred J. Lewy recommends a regimen of low dose priming with 400–500 micrograms of melatonin at 4pm and then a full dose of 3 milligrams of melatonin at midnight. The 4pm priming dose helps pull back the delayed onset of the body’s secretion of melatonin toward a more normal schedule.
