Sometimes we receive comments on FB that make us realize a few of our visitors strongly disagree with our point of view.

For example, one recent visitor disputed our statement that light therapy did better than fluoxetine, the generic form of Prozac, in an experiment comparing these two treatments. She appeared unhappy with our claim that light therapy won hands-down in a clinical trial.

She also thought our light box was overpriced in comparison to another brand she mentioned. The lamp she mentioned was cute, but had a screen about half the size of our $179 light box.

What we both agreed on, however, was that people should do their own research on the efficacy of light boxes. Light boxes are not regulated by the FDA, so no one certifies that a manufacturer’s claims are true. Therefore it is important to consult with trusted experts, or the scientific literature, before making a purchase, or trying light therapy.

CET’s View of the Research

At CET, we do not know of any clinical trials of light therapy that used a small screen like the one our visitor referred to.

What we do know a bit about is trials with large screens. These trials both used light boxes with large screens. The results  appear in peer-reviewed journals, and the abstracts can be accessed at PubMed, the government’s national library of medicine.

The advantage of a clinical trial is that you collect data on a lot of people in a scientific way. A particular drug might work like a charm for ten people, but not work well for 100 other people with the same apparent problem. Or, as often happens, people with depression just get better, regardless of the treatment they are on. Then they attribute getting better to the treatment.

That is why any treatment for depression — drugs, light therapy, cognitive behavior therapy, transcranial magnetic stimulation, and so on – needs to be tested with a group of people, or groups of people, under controlled conditions, to get credible results.

A Convincing Trial with Major Depression

Here is a clinical trials by psychiatrist Raymond Lam, MD, summarized by CET as A Game Changer in the Treatment of Depression

This study is in PubMed as:

Lam RW, Levitt AJ, Levitan RD, Michalak EE, Cheung AH, Morehouse R, Ramasubbu R, Yatham LN, Tam EM. Efficacy of Bright Light Treatment, Fluoxetine, and the Combination in Patients With Nonseasonal Major Depressive Disorder: A Randomized Clinical Trial. JAMA Psychiatry. 2016 Jan;73(1):56-63.

In this study, Dr. Lam used light boxes with a broad screen. The effect size (a measure of effectiveness) for light therapy in this trial was .8. That is considered large. (A large effect size is .8 or more.) The effect size for fluoxetine (Prozac) was .2. This did not differ from placebo. When one treatment has a large effect size, and another does not, I would say the first treatment beats the other hands-down.

However, I thought it interesting that both treatments together had an effect size of 1.1.

That suggests that light therapy would be a good first choice before antidepressants. If light therapy doesn’t work for a particular individual, adding fluoxetine (Prozac) might make sense. Adding cognitive behavior therapy for depression might be another good choice, depending on the preferences of the client or patient.

A Convincing Trial with Bipolar Depression

Another study was done by psychiatrist Dorothy Sit, MD, at Northwestern. …And the Winner Is: Bright White Light for Bipolar Depression summarizes this study.

The full study can be found at PubMed:

Dorothy St, M.D.

Sit DK, McGowan J, Wiltrout C, Diler RS, Dills JJ, Luther J, Yang A, Ciolino JD, Seltman H, Wisniewski SR, Terman M, Wisner KL. Adjunctive Bright Light Therapy for Bipolar Depression: A Randomized Double-Blind Placebo-Controlled Trial. Am J Psychiatry. 2018 Feb 1;175(2):131-139.

This was a study of people in the depressed phase of bipolar disorder. In it, 68% of those subjects who used a light box with a broad screen for six weeks got completely well. Further, no one flipped into mania or hypomania.

Bipolar depression is particularly difficult to treat because it does not respond well to antidepressants, and antidepressants may flip a patient with bipolar disorder into mania. For those reasons, the FDA has never given an antidepressant an indication (approval) for bipolar depression.

Join the Conversation!

Do these studies persuade you that light therapy with a broad screen is effective? If you read these papers, and are not convinced that light therapy with large screens is effective for treating depression and bipolar depression, we would appreciate knowing what doesn’t convince you, and what kind of data you would have to see to be persuaded.

Also, if anyone has research showing small lamps are effective, we would like to see it since we have never seen such a study.

We look forward to hearing from you. Your questions and comments are welcome at