TABLE OF CONTENTS
- What is seasonal affective disorder (SAD)?
- Our natural light problem
- How does light therapy work for mental health?
- Leading medical professionals using light therapy
- Emerging clinical research on light therapy and depression
- Light therapy for TBI & depression
- Light therapy and obsessive compulsive symptoms
- Laboratory studies on light therapy and depression
- The depression-sleep connection
- Light therapy for circadian rhythm and sleep
- Side effects and risks of red light therapy treatments
Emerging clinical research is showing potential for light therapy to treat depression and seasonal affective disorder (SAD). This post examines this initial research and breaks down the connections between mood disorders, natural light intake, and sleep.
What is Seasonal Affective Disorder (SAD)?
Seasonal affective disorder (SAD) is a type of depression with a seasonal pattern.  SAD symptoms impact the most people in late fall and early winter when there’s less sunlight and natural light exposure.  SAD impacts at least 5% of Americans, and is also called seasonal depression, winter depression, or the winter blues. It can also include summer depression. 
Symptoms of Seasonal Affective Disorder: Common symptoms of SAD include low mood, difficulty concentrating, loss of interest, weight loss and weight gain, and sleep problems. 
Treatments for Seasonal Depression: Current treatments for SAD are similar to treatments for other forms of clinical depression, including psychotherapy and antidepressant medications. Some people address SAD symptoms with consumer treatment options like bright white light therapies that mimic the light intensity of the sun.
Emerging clinical research is also showing potential for treating SAD and depression with natural light treatments, like red and near infrared (NIR) light therapy.
This article provides an overview of the encouraging preliminary research that’s been conducted on light therapy as a treatment for depression. This post expresses health information; light therapy is not meant to replace a trusted healthcare provider, health professional, or cognitive-behavioral therapy.
Our Natural Light Problem
It can be very difficult to get enough natural sunlight and vitamin D in the winter months, when the days get shorter and darker. Plus, because of jobs and other daily commitments, people in the United States spends over 90% of their time indoors. 
People who have not been diagnosed with a form of depression can be negatively affected by a lack of natural light too. For example, lack of natural light exposure in the workplace has been shown to affect brain chemicals, resulting in higher levels of cortisol and lower levels of nighttime melatonin, which are associated with depression symptoms and poor sleep quality. 
Bottom line: due to no fault of our own, it can be a major challenge to get enough natural light, especially in the winter, with negative consequences for health and well-being.
Red Light Therapy is a Natural Light Source: “Red light therapy” refers to LED treatments that deliver wavelengths of natural red and near-infrared light. This does not include white light, blue light, full spectrum light, and it is not the same as bright light therapy, or a light therapy lamp, light box, or happylight. Generally, “red light therapy” describes natural light treatments that deliver the same therapeutic wavelengths as natural sunlight, which differs from artificial light treatments like tanning or a bright light therapy box.
This article gives a good general overview of what RLT is and how it works. For mental health treatment, NIR wavelengths may be most effective in treating depression, because they can reach deeper into body tissues than red light. 
When NIR light from a clinical light therapy device is shined on a person’s head, those wavelengths are actually able to go beyond the surface of the skin, and reach the brain and affect brain cells directly. Natural light is absorbed by the mitochondria, which boosts cerebral metabolism, improves neuroplasticity, and decreases inflammation, according to cutting-edge depression research.  More natural light for your brain cells has also been found to improve the metabolic capacity of your neurons, increase oxygen consumption, and boost cells’ ATP energy production. 
See all the health benefits of red light therapy here.
Check out this red light therapy device guide to learn the most important treatment factors.
Leading Medical Professionals Believe Light Therapy Can Potentially Have a Big Impact on Depression Treatment
Dr. Michael Hamblin of Harvard Medical School is one of the world’s leading photomedicine researchers, and a member of Joovv’s Scientific Advisory Board. He believes that in addition to the brain, natural light is also absorbed “systematically through the skin,” resulting in increased circulation, which may positively impact the brain and mental health.
Dr. Marc Schoen of UCLA Medical School has 25+ years of experience treating psychological disorders. In the last few years, Dr. Schoen has found success treating patients’ acute, recurrent major depressive episodes with natural light treatments, in conjunction with medication and psychotherapy.
“In tandem with psychotherapy and/or hypnosis, using red and NIR light therapy appears to catapult patients out of an acute depressive state faster than any other modality I've used,” says Dr. Schoen.
Dr. Schoen has also observed that red and NIR light therapy speeds up the recovery process for patients with serious depression.
“Using pharmaceutical interventions, along with psychotherapy and/or hypnosis, for patients with acute, recurrent major depressive episodes requires extended periods of time for results to materialize,” says Dr. Schoen. “Adding red and NIR light therapy appears to significantly speed up the healing process.”
In the coming years, more and larger clinical studies will be required, but emerging research is already showing how natural light therapy’s effects on the brain can produce significant antidepressant and anti-anxiety effects that we’ll discuss below.
See more experts who use red light therapy here.
Emerging Clinical Research Shows Potential for Natural Light as a Safe, Effective Treatment for Depression
In 2018, leading mental health researchers conducted the Elated-2 Pilot Trial to test transcranial near infrared light therapy for people with major depression symptoms. This double-blind, sham-controlled trial was one of the first of its kind. Its positive findings have encouraged optimism about wider use of natural light treatments for people with depression. These are the highlights :
Natural Light Treatments for 8 Weeks: Patients with major depression who participated in the Elated-2 trial were given natural light treatments directed at their head twice a week, for 8 weeks.
Light Therapy had Antidepressant Properties: Elated-2 researchers concluded that transcranial light therapy “demonstrated antidepressant properties with a medium to large effect size in patients with major depressive disorder.”
Safe and Well-Tolerated: Crucially, researchers noted that natural light treatments were well tolerated by patients, with no serious side effects or reactions. The lead author of the Elated-2 trial, Dr. Paolo Cassano, also co-authored a 2019 meta-analysis of light therapy for major depression. Assessing the base of clinical literature, the authors concluded that it was a “low risk, inexpensive treatment” and that the preliminary evidence supports its potential for the treatment of major depression. 
See all the benefits of red light therapy here.
People with TBI and Depression Improved with Light Therapy Treatments
A 2017 study of 39 people with traumatic brain injuries (TBI) and mild-to-severe depression symptoms also showed notable antidepressive effects from light therapy treatments. 
36 of 39 Patients Showed Major Improvements: Depression assessments indicated a “robust response” for 36 of 39 patients. For 32 of these patients, improvements were significant enough to indicate a remission from depression.
Greater Improvements with More Natural Light Treatments: The trial showed that patients who were treated more often, with more total natural light treatments, registered better results than people who did fewer treatments.
Suicidal Ideation Resolved for Most Patients: The authors noted that “suicidal ideation resolved in all but two patients.”
Long-Term Remissions: With follow-up assessments, the authors concluded that patients “remained in remission for up to 55 months after a single course of treatment.” This is just one result, and more studies are required, but positive data like this gives reasons for optimism.
A separate case study from 2018 has also shown that patients with back pain who treated it with red light therapy experienced not only pain relief, but improvement in depression symptoms as well. 
Read more about brain injuries and red light therapy here.
You can also read up on the potential brain health and cognitive benefits of red light therapy.
Improving Obsessive Compulsive Symptoms with Light Therapy
Anecdotally, clinicians like the aforementioned Dr. Schoen at UCLA have also seen initial success treating some of the more debilitating mental health symptoms of major depressive disorder.
In patients with obsessive, compulsive symptoms like hair pulling or skin picking, I've seen improvements in symptoms with the use of red and NIR light therapy that are superior to using just psychotherapy and psychotropic interventions alone.
Laboratory Studies on Light Therapy Show Anti-Depression and Anti-Anxiety Effects
Initial laboratory studies on light therapy and depression are also indicating positive results. Several recent trials have demonstrated anti-depressive an anti-anxiety effects of light therapy in mammal models.
Examining brain chemistry, these trials have shown that light therapy treatments increase antioxidant and serotonin levels, while decreasing cortisol, nitric oxide, oxidative stress, and neuroinflammation. [10,11] Another trail concluded that light treatments were “as effective as Citalopram” for treating depression-like behaviors. 
The Depression-Sleep Connection
More research is showing how closely mood and sleep disorders are interconnected. Insomnia and other sleep disturbances are a common symptom of depression.  Parts of the brain that regulate sleep have also been found to closely affect mood.  A 2013 review concluded that “nearly all people suffering from mood disorders have significant disruptions in circadian rhythms and the sleep/wake cycle.” 
This Greatist post on natural light and serotonin gives a good background on the connections between natural light intake, mental health, and sleep. It also mentions using Joovv’s red light therapy devices to get more natural light, even when you can’t get more sunlight. The author spoke to Sujay Kansagra, MD, the director of Duke University’s Pediatric Neurology Sleep Medicine Program:
“Depression and sleep are well-known to affect one another,” said Dr. Kansagra. “Insomnia is a common complaint amongst those experiencing depression. Similarly, having an underlying sleep disorder or chronic sleep deprivation can make you more prone to mood dysfunction.”
Read more about red light therapy and sleep here.
Light Therapy for a Healthy Circadian Rhythm and Restful Sleep
Beyond the direct treatment of depression, bipolar disorder, and the brain, light therapy research has demonstrated positive results for the treatment of sleep disorders.
Excess artificial light exposure, especially during the wrong times of the day, can throw off your circadian rhythm similar to jet lag, and make it difficult to fall asleep and stay asleep at night, even when you’re tired. Natural light treatments are a well-documented treatment to improve sleep quality.
You can read the details about the sleep benefits of red light therapy here.
Natural Melatonin with Natural Light: Another aspect of light therapy’s sleep benefits is that they’ve been found in some studies to increase the body’s natural melatonin production. Many people take melatonin supplements as a first step when trying to regulate their sleep, but this can actually increase dependence and reduce your body’s natural ability to make melatonin hormone. Natural light treatments do the opposite, boosting melatonin, which helps you sleep better. 
“Your body will naturally produce melatonin from red light, and medical research from many clinical trials has shown improved sleep disorders from red light therapy,” says Dr. Michael Hamblin.
Other benefits associated with natural light treatments include healthier, rejuvenated skin, natural pain and inflammation relief, and improved fitness and training, to name just a few. The initial research is also encouraging for mental health treatment and forms of hormone regulation.
Side Effects and Risks of Red Light Therapy Treatments
Red light therapy has been tested and analyzed in thousands of peer-reviewed trials. The consensus among medical researchers and the clinical community is that natural light treatments are safe, well-tolerated, and produce little to no side effects. Research teams have concluded this in study after study.
Researchers from Harvard Medical School conducted a review of red light therapy in 2013 and praised its “noninvasive nature and almost complete absence of side effects.” 
Red light therapy does not use heat to induce a biological reaction like some therapies, and is not a heat risk to skin. People with specific photosensitivity concerns should check with their healthcare provider.
Check out Joovv’s FAQs for optimal red light therapy use to see details about other health concerns and potential risks.
Disclaimers and Considerations: The information on this page is meant to educate readers about the science and research behind light therapy and mental health. Consult a trusted health care professional for the diagnosis and treatment of specific medical conditions.
Joovv’s light therapy products are registered with FDA as class II medical devices for the treatment of pain, strain, and inflammation. Other health benefits mentioned in this article are for educational purposes only and not intended to support the safety or effectiveness of Joovv’s devices, and not meant to diagnose, treat, cure, or prevent a disease. The information presented is based on peer-reviewed clinical research, including information about emerging studies and scientific inquiries.
 American Psychiatric Association
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