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How to regulate circadian rhythms and regulate mood using dark therapy.
Last month we taught you how evening light can worsen mood. Today we teach you how to fix that.
Welcome to PsychPearls podcast with Psychiatric Times, "the voice of psychiatry." With thoughtful insights into the world of mental health, this podcast provides timely clinical commentary and practical cutting-edge pearls for you and your practice. We hope you enjoy.
I’m Chris Aiken, the Mood Disorders Section Editor for Psychiatric TimesTM and the editor-in-chief of the Carlat Psychiatry Report, and I’m Kellie Newsome, a psychiatric NP and the cohost of the Carlat Psychiatry Podcast.
KELLIE NEWSOME: Evening light worsens sleep and mood, and last August we unraveled the biology behind that association. To recap, evening light – particularly the blue wavelength suppresses melatonin, worsening 2 systems that are already fragile in people with mood disorders: sleep and circadian rhythms. In animal studies it even altered the core architecture of the brain – shrinking the dendritic spines that help us learn while we sleep.1
But you don’t have to go into the woods and live deliberately to fix this problem. Today, we’ll teach you how to use blue light filters to stabilize the circadian rhythms that regulate mood and sleep, and how to use them in dark therapy, a behavioral therapy for mania.2
Blue Light and Lunar Cycles
CHRIS AIKEN: There are 2 well-known photoreceptors in the eye. The rods see black and white, and the cones add color vision. But in the 1990s a new photoreceptor was discovered – melanopsin – which only responds to the blue wavelength of light. This photoreceptor doesn’t help us see, but it does regulate our circadian rhythm. In the past, this system worked well because we didn’t have much blue light in the evening. There were candles, starlight, fireplaces – all yellow light.
KELLIE NEWSOME: Except once a month when the blue moon was full. And it’s no coincidence the word lunatic arose in the middle ages as a term for mental illness. It was believed that some people went into temporary bouts of insanity that followed the lunar cycle – the moon. Seven hundred years later, reports linking the full moon to worsening of psychiatric disorders continue to roll in.3
Blue Light Blockers
CHRIS AIKEN: And in today’s world, every night is a full moon, because cell phones, plasma TVs, and energy efficient bulbs emit a lot of blue light. But technology has also come to the rescue in the form of blue light filtering glasses. These are amber colored glasses, and when you wear them they filter out close to 100% of blue light. They’ve gained popularity among sports figures and celebrities, because wearing them at night improves sleep – which then raises cognitive and athletic performance. But most models out there do not filter enough blue light to make a meaningful difference in psychiatric disorders. We recommend the glasses that were used in the clinical research – and there are 2 types. Some studies have used Uvex glasses, which are $10 to 15 dollars on Amazon. Any pair on that site will work, and these are much better quality for a higher price, around $50.
KELLIE NEWSOME: I keep a pair of these glasses at my desk for patients to try on. They’re usually surprised to see the world looks quite pleasant through them. They don’t make things dark, but give the world a relaxing, yellow hue. Some patients find them so soothing that I have to warn patients not to wear them during the day, because doing so will flip their circadian rhythm in the wrong direction. When you wear them, your brain will think it’s in pitch darkness, and we only want that effect at night.
CHRIS AIKEN: Wearing them has real biological effects. When you put them on, your melatonin starts to rise, the same as it does in a pitch-dark room.4 Sometimes patients ask if they can just take melatonin instead, but that doesn’t have the same effect. In a recent randomized controlled trial, taking artificial melatonin did nothing to stabilize mood in bipolar disorder.5 So it’s not enough to have melatonin drizzled on the brain. There are other biological effects involved in pumping out the brain’s indigenous melatonin that are necessary here.
If you want to know more about the biological effects of light and darkness listen to our August 2nd podcast on Blue Light, Depression, and Bipolar Disorder. Now, let’s move on to the clinical research.
Origins of Dark Therapy
KN: In the 1980s Thomas Wehr, MD, and Norman Rosenthal, MD, made a surprise discovery while working at the National Institute of Mental Health (NIMH). Some patients had worsened depression in the wintertime that improved with light therapy. Their research suggested that circadian rhythms played a strong role in mood disorders, something that was already hinted at by the high rates of insomnia in major depression and the fact that a night without sleep often triggered an episode of mania. So, Wehr turned his attention from morning light to evening darkness. He began with normal subjects and placed them in a pitch-dark room for 14 hours overnight, imitating a dark winter night where the sun goes down at 6 PM and rises at 8 AM. The subjects were a little sleep deprived before the experiment, getting about 7 hours per night, something Wehr thought might be due to the artificial evening light of modern life. After a few weeks in the dark bedroom, their sleep stabilized to 8 hours and 15 minutes per night, closer to the recommended amount an adult needs.6,7
CA: Then in 1994 a man came to the NIMH seeking help for rapid cycling bipolar disorder. Most patients don’t call up the NIMH to get help, so we can imagine this man had a pretty bad case. He was a successful engineer with a hyperthymic temperament, but in his 40s he became depressed and started fluoxetine and nortriptyline. He got better on this combination, but then went into a 4-year bout of rapid cycling moods cycling in and out of depression and hypomania every 1 to 2 months. Mood stabilizers did not help, so he came to the NIMH. Wehr knew that sleep disruption could trigger rapid cycling, and he wondered if his super-dark room could stabilize it. He put the patient through the same protocol he used for sleep, placing him in a pitch dark room for 14 hours each night. With this dark therapy, he improved so rapidly that they eased the schedule from 14 hours of darkness to 10 hours each night (10:00 PM to 8:00 AM). He stayed well with that regimen, and that is how dark therapy was born.7
KN: But the treatment didn’t really take off. First, it’s hard to get patients in a pitch-dark room overnight. We’re talking so dark that you can’t see your hands in front of your face. Second, we need more than an intriguing case report to put this into practice. The first problem was resolved in the early 2000s by James Phelps, MD.
Phelps was working in private practice in Oregon when he chanced upon 3 discoveries that would open up new therapeutic doors in bipolar disorder. First, he learned about Wehr’s research on dark therapy. Then he learned about the new photoreceptor, melanopsin, that set the circadian rhythm by responding to blue light. He wondered if dark therapy could be accomplished by blocking only the blue wavelength of light, and that brought him to the third piece of the puzzle: blue light filtering glasses. Other fields of medicine had already raised alarms about the hazards of evening blue light (such as increased risk of cancer and heart disease) and a company was manufacturing these to improve sleep and health. Phelps called this virtual darkness and tried the glasses out on his patients. For some, the glasses did nothing, but about half of his patients reported their sleep was better when they wore the glasses 1 to 2 hours before bed.8
He then discovered that welders used the same blue-light filters to protect their eyes at the local welding shop, and this opened the door to more treatments because these factory grade lenses were only $7. Phelps tested them and the fit the bill. Consumer Reports later ran tests of blue light blockers and also concluded that the Uvex safety lenses he was using were among the strongest filters.
Phelps tested the waters, but the definitive study was a full-scale randomized trial in patients who were hospitalized for mania. In addition to treatment as usual, half wore amber lenses in the evening, and half wore (placebo) gray lenses, until sleeping in a pitch-dark room. The improvements were dramatic over the first week, with a large effect size of 1.9, while the control group barely changed.2
You don’t need to be in the hospital to do this therapy. Phelps has had success using it in an outpatient practice, and we have as well. Here’s how you do it.
The original protocol required manic patients to be in either pitch darkness or virtual darkness (that is, with the amber glasses on) for 14 hours, from 6:00 PM to 8:00 AM. It took about a week for the mania to improve, and as it did the protocol was relaxed a bit, from 14 hours per night to 10 hours per night. So instead of putting the glasses on at 6 PM, they’d put them on at 7:00 PM, then 8:00 PM, and for prevention thy would move it to 9 or 10 PM. They don’t wear the glasses while asleep. That’s what the pitch-dark bedroom is for. But they do put them on if they are awake and the lights are on.
And the pitch darkness really does matter. Even light as dim as a nightlight on can interfere with melatonin secretion. In a large epidemiologic study of older adults, sleeping with a night light on doubled the risk of depression over 2 years compared to a pitch-dark bedroom.9
But how do they get their bedroom pitch dark in this electric light world? Black out curtains, electrical tape over LEDs, towels or draft snakes under doors, or sleeping in the basement. If there is still stray light, patients can also sleep with a good eye mask.
CA: One problem we run into is patients who feel they can’t sleep without the TV on. Usually the reason is depressive rumination. These patients rely on the TV to distract them from their negative, ruminating thoughts. If that’s the case, we recommend ambient music or boring audiobooks instead. Another problem is patients who are afraid of the dark, such as those with PTSD. Here we have a technological solution. They can use amber colored nightlights that don’t emit any blue light. They are available for around $12.
KN: One modification we don’t recommend is to rely on blue-light filters on laptops and cell phones. Most devices have a setting that turns down the blue in the evening, and no doubt this is certainly a good thing and we’d recommend it in conjunction with dark therapy, but it doesn’t filter 100% and it isn’t going to take care of the background lights. You can find this feature in your smart phone’s settings, or if you’re using a laptop try downloading f.lux (spell it out) for windows or Candlelight by Oliver Denman for Mac.
But what if your patient can’t put the glasses on at 6 PM? Remember the 14-hour protocol was used for hospitalized mania, and they loosened it up as the patient got better. In practice, you might use dark therapy for hypomania, mild mixed states or as an intervention for early signs of mania. In those cases, putting the glasses on 2 hours before bed might be enough.
CA: It’s also important to set up expectations. Tell your patient that dark therapy is going to help stabilize their mood, but it may not help them fall asleep. Here’s an interesting pearl from that controlled trial. The patients who got better with the dark therapy didn’t actually sleep more. They slept a little less than the placebo group, but their sleep did get more regular. It went from sleeping and waking at random times to a more steady, stable circadian pattern.2 A lot of times patients will give up on dark therapy because they think it is supposed to help them sleep.
Dark Therapy for Insomnia
KN: Dark therapy improves mania, but what does it do to sleep? We found 3 randomized controlled trials that tested them out in insomnia, and they had a large effect, helping patients stay asleep longer, fall asleep earlier, and deepening sleep quality.10-12 One of them used the blue light blockers as an adjunct to CBT-insomnia, where half the patients had the behavioral therapy with placebo glasses and half used the blue-light blockers. Not only did sleep improve with the blockers, but so did anxiety and depression.10 Another study looked at performance on cognitive tests after wearing the glasses, and that got better as well, probably because the patients were sleeping better.11 In the sleep studies, patients put the glasses on 1.5 to 2 hours before bedtime.
Blue light blockers have been used successfully in jet lag, and they tend to help night owls fall asleep earlier.
CA: I wear them myself and I can attest to that. I’m more patient and have better attention, a little quicker on my feet, the next day if I wore them before bed.
Dark Therapy for Depression
KN: Blue light blockers have a big effect in mania and rapid cycling, and for sleep they deepen sleep quality and turn night owls into morning people. But can they help depression? We know from animal studies and epidemiologic studies that blue light causes depression, but when it comes to clinical studies using blue light blockers to treat depression the results are mixed. In that CBT-insomnia study, they did improve depressive symptoms, but those patients had clinical insomnia, not clinical depression.10 Beyond that, we have only 2 controlled trials, 1 positive, 1 negative. The positive one 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.13 The negative study was also small (n = 20) and included depressed patients with insomnia. The investigators suspected that the glasses might not have worked because the patients found them uncomfortable and did not wear them as much as they should.14
CA: When worn at night, blue light filters have beneficial, biological effects, but can they have side effects? Nothing major showed up in the studies. Possibly headaches, and there are reports of depression in some patients. This usually improves by putting the glasses on later, say, 7 PM or 8 PM instead of 6 PM. Although you can see pretty clearly through the glasses, color vision is distorted so we don’t recommend them while driving.
KELLIE NEWSOME: We have links to recommended brands of blue-light blockers in the text to this podcast. We hope to see you again on PsychPearls, and you can also catch us every Monday on the Carlat Psychiatry Podcast.
Chris Aiken, MD, is the Mood Disorders Section Editor for Psychiatric TimesTM, the Editor in Chief of The Carlat Psychiatry Report, and the director of the Mood Treatment Center. He has written several books on mood disorders, most recently The Depression and Bipolar Workbook. He can be heard in the weekly Carlat Psychiatry Podcast with his cohost Kellie Newsome, PMH-NP. The author does not accept honoraria from pharmaceutical companies but receives royalties from PESI for The Depression and Bipolar Workbook and from W.W. Norton & Co. for Bipolar, Not So Much. Kellie L. Newsome, PMH-NP, is the cohost of the Carlat Psychiatry Podcast and is also a practicing psychiatric mental health nurse practitioner in Winston Salem, NC, at the Mood Treatment Center. Raised in Tasmania, Australia, Kellie moved to the United States in 1998.
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