Synopsis: Light therapy works not just for seasonal affective disorder but also is used to treat major depression and bipolar depression. It is important to follow the right steps in light therapy to determine if it works for you.

BY LEN LANTZ, MD / 9.19.20; No. 33 / 7 min read

Disclaimer: Yes, I am a physician, but I’m not your doctor, and this article does not create a doctor-patient relationship. This article is for educational purposes and should not be seen as medical advice. You should consult with your physician before you rely on this information. This post might also contain affiliate links. Please click this LINK for the full disclaimer.

What is light therapy?

Light therapy, or bright light therapy, is a treatment originally used to target seasonal affective disorder (SAD), a depressive disorder that tends to start in the fall, worsen in the winter and lift in the spring. Most people know if they have SAD because they can feel the dread of it coming on as the days get shorter and the weather gets cooler in the fall.

In addition to sadness, people who experience SAD often have “atypical symptoms” of depression, such as extreme fatigue, increased appetite and carbohydrate craving. The idea behind using light therapy to treat SAD is that it makes up for the lack of sunlight during the day, as the decreased light to our eyes is suspected to be the main cause of SAD. Bright light therapy is thought to have a corrective impact on the circadian rhythm and systems involving serotonin, melatonin and CLOCK genes. Using bright lights at the beginning of the day and following other correct steps can be effective for many people who suffer from this form of depression.

While there are mixed data for light therapy, it clearly works for some people

If you are a purist and only look at the Cochrane database for medical research, then you will be unimpressed with the medical studies to date on light therapy for depression (Nussbaumer-Streit, et al. Cochrane Database of Systematic Reviews. 2019). However, there are several good studies which show that light therapy for seasonal affective disorder is effective. For example, in one study light therapy for SAD was as effective as an antidepressant (Ruhrmann, et al. Psychol Med. 1998).

In a more recent large, placebo-controlled study of SAD (Lam, et al., Am J Psychiatry. 2006), it was found that both Prozac and light therapy were better than placebo in treating SAD and that the light therapy had a faster onset of recovery and fewer side effects than Prozac.

My colleagues and I also have seen in our own patients that some people experience a clear benefit from light therapy for their fall/winter depression, though others do not.

Most people attempt light therapy incorrectly

Unfortunately, the majority of people who attempt light therapy miss one or more critical steps. Maybe they bought the wrong light. Possibly the instructions were poor. More often than not, the reason that light therapy does not work is that the person using it does not sit close enough to the light, regularly enough and for long enough. Keep in mind that if you have severe depression, light therapy alone is unlikely to be enough to help you. If you have a major mood disorder, it is a good idea to utilize light therapy under the supervision of a psychiatrist.

Here are some general guidelines for using light therapy:

1. Buy a 10,000 lux light therapy lamp with a UV filter. It is important to read the specifications of your light therapy lamp to know if it can produce an intensity of 10,000 lux at the distance your eyes are from the light. Keep in mind that some light therapy lamps that are sold are just too weak or small to work. If I were in the market for a light therapy box that had the right specifications, I would be looking at the Alaska Northern Lights website (I have no affiliations with this company).

2. Schedule time every morning. Block out 30 minutes in your schedule every day over the fall/winter for this therapy. This is your time for you. Do not do this treatment later in the day, as the treatment tends to be activating and later treatment increases the risk of insomnia.

3. Sit down in a chair facing the light and stay there. When you get up from the chair or turn your head away from the light, you diminish the quality of your treatment. If the light is at a slight angle to your face, ensure that the angle does not exceed 45 degrees. Only plan to get up from the chair during the 30 minutes if you absolutely need to. This is your time. Everyone and everything else can wait.

4. Place the light 18-24 inches from your eyes. Use a measuring tape because you will likely guess the distance incorrectly. The light therapy lamp will feel really close to your face. Nearly every advertising picture you see of people using light therapy is misleading in that the light is much too far away or is placed at a 90-degree angle. In theory, you can have the light therapy lamp farther away but treatment will need to last significantly longer, as the power of light diminishes exponentially the farther away you are from it.

5. It is not expected or recommended that you stare at the light. You can read, text, surf the internet or watch TV during treatment as long as your face is directed toward the light and your eyes remain the required distance from the light therapy lamp. It is best if you refrain from walking or running on a treadmill during treatment, as it can interfere with your eyes being the correct distance from the light. Directly staring at the light is not recommended and will increase your risk of a headache from the therapy.

How will I know if light therapy works for me?

It is quite important that you measure the effects of light therapy on your mood. Your time is valuable, so be thorough and do a little research on yourself. There is a helpful measurement tool for depressive symptoms called the Patient Health Questionnaire (PHQ-9) that you can use for free. For more information on depression rating scales, please read my article, “Depression Rating Scales – Getting Unstuck.” You can click HERE for a downloadable pdf of the PHQ-9. To measure your progress, complete the PHQ-9:

1. Just before your first light therapy session

2. After 2 weeks of light therapy

3. After 4 weeks of light therapy

At the 4-week mark, determine if your mood has improved. Of the people who see improvement in SAD from light therapy, most see improvement by week 4. If you are 65+ years of age, consider continuing the therapy for at least 6 weeks, and repeating the PHQ-9 at week 6.

Light therapy can be used to treat mood disorders other than SAD

Bipolar Depression – There is evidence that light therapy can help treat bipolar depression when used as adjunctive therapy. A recent randomized, double-blind placebo control trial showed a 68% remission rate (remission means full freedom from depression) in the treatment group and a 22% remission rate in the placebo control (Sit, et al. Am J Psychiatry. 2018).

Major Depression (non-seasonal) – Light therapy has been shown to be beneficial as part of a treatment called triple chronotherapy (the other 2 components involve sleep deprivation and sleep phase advance) for major depression. When used as a component of triple chronotherapy, bright light therapy has been associated with 33% to 77% remission rates (D'Agostino, et al. J Affect Disorder. 2020).

There are risks in utilizing light therapy

Light therapy has potential negative side effects, which is why it is good to utilize it under the direction of a physician knowledgeable in its use. For example, many people with bipolar disorder require shorter duration or decreased frequency due to the risk of mood destabilization, insomnia or a switch to mania.

While I’m not including every possible risk, common side effects from using light therapy include headache, eye strain, sleep disturbance, irritability/agitation and nausea. There also exists the possibility that cumulative exposure to bright light such as through light therapy for depression could accelerate age-related macular degeneration, however, one study found no adverse impact from eye examinations after 5 seasons of using bright light therapy (Gallin, et al. Am J Ophthalmol. 1995).

A story about using light therapy for fall and winter depression

“Jane” lived in Montana and struggled every winter with depression. Each fall around September she could feel her depression start to come back. It almost felt like a physical sensation, like a dull headache that grew and grew into a raging headache. But instead of her head hurting, she experienced sadness, loss of energy, low motivation, less pleasure in life and she slept and ate excessively. Her symptoms would continue to build until January or February and then start to lift as she got closer to spring. By late spring or early summer, she felt back to her normal self.

Jane tried several strategies to combat her seasonal affective disorder. She took a walk outside over her lunch hour every day – even if it was below zero! She practiced hot yoga several days of the week and had also tried antidepressants, from which she saw a partial benefit.

Last winter, she decided to try light therapy. She bought a quality light therapy lamp and started using it daily for 30 minutes by October. She was surprised by several things. The first was that it took a bit more effort than she expected to get used to the bright light every morning. The second surprise was that it worked and she saw significant improvement by the 2-week mark. She found that she had better motivation and energy, less sadness and she did not find herself snacking every free moment of the day. She also kept doing the other positive physical activities that were part of her winter routine. After finding light therapy to benefit her mood, she decided to use it every fall and winter season.

Light therapy might be right for you

Imagine being free from depression in the fall and winter. Light therapy can be very helpful for seasonal affective disorder and other forms of depression. If you tried it in the past and it didn’t work, you might consider another attempt, this time following all the steps above. Light therapy has helped many people feel much better as they move through fall and winter months by improving their mood, energy and outlook. It can be a natural solution to a recurring problem for many. Think about whether light therapy would be right for you. Work with a doctor who knows about its use. Using light therapy might help you reduce or eliminate seasonal depression and other forms of depression and motivate you on your journey to full freedom from depression.

For further reading, check out:

• Len’s article “A Plan for Stubborn Depression”

• Len’s article “How Does Yoga Help Depression?”

• Len’s article “The Surprising Results of Exercise for Depression”

• Len’s article “Medical Causes of Depression”

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