This PsychSnap was updated October 7, 2025. It was originally released October 6, 2023.
Michelle is a 45 yo woman with a history of recurrent major depression. She took several antidepressants in her 20s that were either intolerable (escitalopram) or ineffective (sertraline, venlafaxine). She has been taking fluoxetine 20mg for many years, which she says “puts a floor” on her depression. Higher doses of fluoxetine make her feel too activated.
She continues to have significant depressive symptoms every 2-3 years without a clear precipitant. She has been in psychotherapy intermittently for many years with some benefit.
Michelle has been doing well for the last 2 years. Today, she reaches out to say that her early signs of depression are back – low energy, difficulty getting out of bed, and an increased desire to be alone. Michelle is working hard to exercise most days because she knows that this can help depression. She is also seeing her therapist weekly and taking the fluoxetine 20mg daily. She asks you if there is anything else that can be done to prevent things from getting worse. She doesn’t want to try anything that might cause her to gain weight.
What would you recommend adding to the weekly psychotherapy and fluoxetine for Michelle?
- Aripiprazole
- Quetiapine
- Bright light therapy
- Bupropion
The list of weight-neutral augmentation agents for major depression is short: psychotherapy, transcranial magnetic stimulation (TMS), electroconvulsive therapy (ECT), bright light therapy, lithium, and methylated folic acid (Deplin). Bupropion doesn’t cause weight gain, but bupropion is not an evidence-based augmentation strategy for major depression. Other augmentation agents for depression commonly cause weight gain, including quetiapine and aripiprazole.
We’ve just entered October, which means that in the United States, we are losing daylight fast. Some people have episodes of major depression that start in the fall and resolve in the spring. Bright light therapy has been studied and shown to be effective for this type of major depression–seasonal depression–since the 1980s. Bright light therapy is also effective in non-seasonal depression, including both unipolar and bipolar depression.
I’m going to 1) summarize a 2016 study that established the effectiveness of bright light therapy for non-seasonal major depression and a 2025 meta-analysis that reached the same conclusion, and 2) tell you what you need to know to advise your patients about choosing and using a light box.
Lam and colleagues randomized 122 adults with non-seasonal MDD of at least moderate severity to one of 4 treatments. All patients took a pill (fluoxetine 20mg daily or a placebo pill) and sat in front of a device for 30 min daily (bright light therapy or a sham control (i.e. an inactive negative ion generator that made noise and was found to be credible with participants)). The experimental groups were placebo, fluoxetine, bright light therapy, and combination (fluoxetine + bright light therapy).
The figure below shows the mean change in MADRS score (a depression scale commonly used in research studies) over 8 weeks. The light gray line represents the effect of bright light therapy on depressive symptoms. As compared with placebo (dark gray line), bright light therapy is more effective for depression after both 4 and 8 weeks. The combination of fluoxetine 20mg daily and bright light therapy (orange line) produced even more improvement in depressive symptoms. Response (defined as a 50% reduction in the MADRS score) was achieved by 50% of the bright light therapy group, 76% of the combination group, and 33% of the placebo group. The Number Needed to Treat for remission of depression for the combination (fluoxetine + bright light therapy) vs placebo was 3.5 (Lam, 2016).
Change in the Scores on the Montgomery-Asberg Depression Rating Scale (MADRS) at Each Treatment Week. Error bars indicate standard error. a, b, and c indicate p < 0.05 vs placebo (i.e. statistical significance)(Lam, 2016).
Not all studies of bright light therapy have been this impressive, but the evidence-base for bright light therapy in non-seasonal depression has continued to grow. A 2025 systematic review and meta-analysis of randomized controlled trials of bright light therapy vs active controls for nonseasonal depressive disorders published in JAMA Psychiatry supported the efficacy of bright light therapy. The review included 11 studies comprising 858 patients – most with MDD and <100 people with bipolar depression. The response rate to treatment with bright light therapy in these patients was 60% vs 39% for controls (OR 2.34; 95% CI 1.46-3.75). The remission rate was 41% vs 24% for controls (OR 2.42; 95% CI 1.50-3.91) (de Almeida 2025).
Michelle is impressed by the data for bright light therapy. She is open to a trial of bright light therapy added to the fluoxetine 20mg that she is already taking (Answer 3!). How should she proceed?
The protocols for bright light therapy for depression are well-established. For either seasonal or non-seasonal major depression, start with 30 minutes of daily exposure to white light at 10,000 Lux as soon as possible after awakening. Lux is a measure of illuminance – in this case, the intensity of light that reaches the eyes. If there is no improvement in depressive symptoms after several weeks, increase the exposure time to 45 or 60 min. If there is no response after 4 weeks, stop the treatment for lack of efficacy.
Early morning is the most effective time for bright light therapy for unipolar depression. However, bright light therapy anytime before 2pm has some benefit.
If depressive symptoms for non-seasonal depression improve with bright light therapy, continue the current dose of light therapy for at least 4 weeks after the resolution of symptoms. In the US, people with seasonal depression should continue bright light therapy until April. It may be possible to reduce the dose without losing benefit, either by reducing the daily exposure time (20 min) or the frequency (every other day). Stopping light therapy mid-winter in people with seasonal depression most commonly leads to depressive relapse within 3 weeks.
Both the efficacy and side effects of bright light therapy are dose dependent. Bright light therapy is generally well tolerated; if overactivation, hypomanic symptoms, nausea, or headaches develop, reduce the exposure time to improve tolerability.
Michelle tells you that she’ll drink her coffee and read the morning paper while doing 30-minutes of bright light therapy in her kitchen. How can she get a light box set up?
Bright light therapy set-up for 10,000 Lux illumination
Apparatus Details: downward-tilted, smoothly diffusing
Photo credit from the Center for Environmental Therapeutics
http://www.cet.org (Terman, CNS Spectr, 2005)
Get the right light box
Be careful. Light boxes are not federally regulated. Claims for effectiveness in depression are generally marketing slogans. Anything small enough to fit easily in a bag is likely to be ineffective. A sunny room does not approach the intensity of light needed for bright light therapy.
Here are 2 specific products to look for, updated to only include models with LED bulbs:
- Northern Light Technologies Desklamp 2 – $250
This light box has been evaluated and is recommended by the non-profit Center for Environmental Therapeutics (CET). - Carex Daylight Classic Plus – $134
This light box is cheaper and meets all of the below criteria. It has been previously used in clinical trials of bright light therapy.
CET also has detailed information on light and dark therapy for both patients and providers on their website (cet.org). Their link for this light box also includes a sample letter that patients can use to attempt reimbursement from their insurance through Durable Medical Equipment.
General criteria that a bright light therapy box should meet:
- Intensity & Size – 10,000 Lux illumination of both eyes at a comfortable distance (at least 12 inches) requires a large screen. Avoid small, portable light boxes. They may advertise 10,000 Lux, but the illuminance may only achieved in a narrow field or at an uncomfortably close distance. If you already have a lightbox, you can check its illuminance at different angles and distances with Smart Phone Apps like Lux Light Meter.
- Light – White light. Blue or full spectrum lamps are not more efficacious.
- Polycarbonate Filter – LED lamps should include a filter to eliminate glare. Fluorescent lamps should include a polycarbonate filter for safety to prevent ultraviolet rays from reaching the eyes and skin.
Read the instructions with the light box and follow them.
Pay particular attention to the distance one sits from the screen, and the height and angle of the light box. Lux is inversely proportional to the square of the distance from the light source, so small changes in how far one sits can render an effective treatment ineffective. Generally people sit at a table or desk and look down at a computer or book or their breakfast. It is fine to wear glasses, as long as they are not tinted or shaded.
Key Points
- Bright light therapy is an effective treatment for both seasonal and non-seasonal depression.
- For depression, start with 30 minutes of daily exposure to white light at 10,000 Lux as soon as possible after awakening.
- Be careful in choosing a light box because they are not federally regulated. The details of the light box set-up are also important, in particular the distance one sits from the device.
Related PsychSnaps:
Can dietary interventions or exercise treat depression? Zoë Kopp, July 2025.
Is adding bupropion to an SSRI/SNRI an effective depression augmentation strategy? Emma Samelson-Jones, June 2025.
References:
Eastman, Charmane I., et al. “Bright light treatment of winter depression: a placebo-controlled trial.” Archives of general psychiatry 55.10 (1998): 883-889.
Lam, Raymond W., et al. “Efficacy of bright light treatment, fluoxetine, and the combination in patients with nonseasonal major depressive disorder: a randomized clinical trial.” JAMA psychiatry 73.1 (2016): 56-63.
Penders, Thomas M., et al. “Bright light therapy as augmentation of pharmacotherapy for treatment of depression: a systematic review and meta-analysis.” The primary care companion for CNS disorders 18.5 (2016): 26717.
Sit, Dorothy K., et al. “Adjunctive bright light therapy for bipolar depression: a randomized double-blind placebo-controlled trial.” American Journal of Psychiatry 175.2 (2018): 131-139.
Terman, Michael, and Jiuan Su Terman. “Light therapy for seasonal and nonseasonal depression: efficacy, protocol, safety, and side effects.” CNS spectrums 10.8 (2005): 647-663.
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