What if I told you that the right kind of light could help cure your depression, improve your sleep, and even mitigate the symptoms of dementia?
Welcome to another installment in my “What is Nature Therapy?” series, part of my goal to create a compendium of well-researched scientific blogs on the various kinds of nature therapy out there. Since there are so many kinds of nature therapy out there, I want to help you find what you need to begin to feel better—with actual scientific facts about what works and what doesn’t.
Today, we’ll be asking and answering the questions: what is light therapy? Who and what is it for? And what does the science say about it? Read on to learn more.
What is light therapy?
If you’ve heard of seasonal affective disorder — more commonly known as the aptly-acronymed SAD — then you’ve probably heard of light therapy, also known as bright light therapy or phototherapy. For those not yet in the know, seasonal affective disorder is a variant of major depression that occurs at around the same time every year. Characterized by depression, fatigue, hopelessness, and social withdrawal, SAD occurs most frequently in climates where certain seasons (depending on your location, worldwide) bring less sunlight.
Light therapy was initially developed as a way to combat SAD. Light therapy requires a light therapy box which gives off a bright light that mimics the outdoor light traditionally supplied by the sun in sunnier climates. By mimicking outdoor light, researchers believe that the light can actually cause a chemical change in your brain which helps reduce your symptoms. This is in part due to the short wavelength light, which mimics the wavelength of the sun, and is thought to help with mood and sleep, mitigating the symptoms of SAD.
However, SAD doesn’t have the monopoly on light therapy. Other uses for light therapy are non-seasonal depression, jet lag, sleep disorders, and even dementia.
About 10,000 lux of light is the right amount, and research suggests the best time to use your lightbox is first thing in the morning for about 20 to 30 minutes. Keep the light box about 16 to 24 inches away from your face — and while your eyes should be open, be sure not to stare directly at the light (the same advice goes for the sun itself!). Keeping your lightbox near your desk while you’re working is a great way to get your daily dose without too much hassle.
NB: the light therapy boxes used for mood and sleep are not the same as the light boxes used for skin conditions like psoriasis. Those other light boxes for skin conditions emit UV light, which can actually damage your eyes and skin. In fact, the light therapy boxes we’re talking about today are actually specially designed to filter out UV light — so make sure you know the difference!
NB2: three of my favorite light therapy boxes are online, all 10000 lux brightness, with timer functions: The TaoTronics Light Therapy with adjustable brightness levels, memory and 90° rotatable stand; the Miroco UV Free with touch control and standing bracket, and the Carex Day-Light Sky Bright Light Therapy Lamp.
Your circadian rhythm
All right, so we’ve explained how it works — but why does it work?
You’ve probably heard of your circadian rhythms, which are regulated by your biological clock in the brain. Basically, your “circadian rhythms tend to move into phase synchrony with environmental rhythms, mainly the day/night cycle.” So when winter comes and the northern hemisphere is plunged into early darkness that lasts well into morning, our circadian rhythms can get a little out of whack. That includes the brain chemicals which light affects.
Researchers from the Journal of Clinical Sleep Medicine expanded upon the relationship between circadian rhythms, light therapy, and sleep and mood disorders in a 2009 paper: “Light therapy targets the biologic (subjective) clock and attempts to reset the phase of the clock’s activity relative to the LD cycle and/or influence its amplitude. A 2019 meta-analysis of 19 studies of bright light therapy showed that 18 found it effective, indicating that using a light therapy box first thing in the morning to help reset your internal clock and get it ticking along the right track is an easy, safe, and effective thing to do.
What does the science say?
There’s been an impressive amount of clinical research that has looked into the impact of light therapy on SAD, depression, bipolar disorder, dementia, and more.
Seasonal affective disorder
A small randomized, double-blind, placebo-controlled, multi-center trial from 2007 looked specifically at the efficacy of a LED light therapy device in the treatment of SAD. Participants aged 18 to 65 with SAD were seen at Baseline and then again after 1, 2, 3 and 4 weeks of treatment. The results found at the trial end showed clear superiority of the LED light therapy device over the placebo condition.
However, there’s also a substantial body of research looking at not just seasonal but non-seasonal depression, and the results are equally impressive: Light therapy is equivalent to prescription antidepressants in many studies.
This systematic review and meta-analysis from 2019 specifically looked at the impact of antidepressants (AD), light therapy (LT), and a combination of both antidepressants and light therapy on people suffering from major depressive episodes. A total of 397 participants with a moderate to severe major depressive episode were included. The results showed that “no differences were observed between LT and AD, with a clear superiority of the combination.”
Here, light therapy on its own was just as effective as antidepressants on their own—and the combination of the two was the most effective of all. Doctors who tend to prescribe antidepressants as the first line of defense might consider light therapy as their new go-to, especially when used in combination with antidepressants. That’s another win for the efficacy of nature therapy!
A randomized double‐blind controlled trial from 2005 looked at the effect of adjunctive bright light in non‐seasonal major depression, using patient‐reported symptom and well‐being scales. 102 patients were treated for 5 weeks with either 10,000 lux of white bright light for an hour a day or 50 lux of red dim light for 30 minutes a day; both groups also received 50 mg of sertraline (aka Zoloft) a day. The results? On all three questionnaires the participants took, “the score differences between baseline and endpoint were greatest in the bright light group” suggesting that light therapy is a valid and useful treatment for non‐seasonal depression.
Those with bipolar disorder (BD) often report difficulty sleeping as one of their core symptoms, and of course depression (as well as mania) is another fundamental symptom of BD, making light therapy a worthy fit for a number of symptoms associated with BD.
An excellent systematic review and meta-analysis was conducted this year to look more closely at bright light therapy (BLT) and depressive symptoms in patients with BD. They ultimately found “significant differences between BLT and placebo” for both depression and BD symptom severity before and after BLT. Another systematic review and meta-analysis was conducted in 2019 to look at the efficacy of light therapy for patients with bipolar depression. They concluded that “positive but nonconclusive evidence that adjunctive light therapy reduces symptoms of bipolar depression and increases clinical response.” Translation: light therapy beat prescription anti-depressants head to head when it came to fighting depression and BPD symptoms—and with no risks. Positive upside with no downsides? We’ll take that bet!
The final area in which research on light therapy is concentrated is dementia. This is the area with the fewest number of rigorous studies, and more study is definitely needed, but it’s worth taking a look.
An randomized, controlled trial of bright light therapy for agitated behaviors in dementia patients residing in long-term care from 1999 found that agitated, demented patients in long term facilities—and sadly, that’s often the case—sleep longer at night when they have bright light therapy in the morning. However, they also found that the positive effect of light therapy only impacts dementia patients who are also suffering from agitated sleep behavior.
A second more recent study from 2010 found more robust results when they looked at light treatment in elderly patients with nonseasonal major depressive disorder. Their double-blind, placebo-controlled randomized clinical trial concluded that light therapy improved mood, enhanced sleep efficiency and produced continuing improvement in mood.
So while the jury’s still out on whether light therapy is specifically helpful for symptoms of dementia, it’s clear that at the very least, it can help older folks both with and without dementia both sleep and feel better. I hope more rigorous research is done in this area, as there’s a lot of potential here.
Light therapy is a helpful tool with a lot of efficacy for mitigating symptoms of depression (both seasonal and non-seasonal), as well as sleep disorders, mood disorders like bipolar disorder, and possibly even dementia. Best of all, there’s very little risk to integrating it into your health toolkit—and a pretty big potential “bright side!” So why not “see the light” on light therapy and give it a try yourself?
(Remember: Nature therapy is a far more diverse and interesting field than people might realize—it’s much more than just “going outside!”—and so the purpose of these blogs is to show you the exciting range, diversity, and nuance of the many therapeutic interventions that fall under the umbrella of nature therapy. You can check out the other blogs I’ve written on the site, on topics like gardening for dementia, therapeutic horticulture, pet therapy, adventure therapy, blue care, ecotherapy, care farms, forest bathing, hydrotherapy, and earthing and grounding.)