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Therapies · product guide

Light therapy box: does it work?

Bright white light for your eyes in the morning. About 10,000 lux for 30 minutes treats winter depression; it's the best-supported device on this shelf.

Moderate evidenceReviewed September 2026

What it is

A light box works through your eyes, not your skin. Bright light reaches light-sensitive cells in the retina that report straight to your brain's master clock, shifting circadian timing and acting on mood pathways. That makes it a different tool from a red-light panel, which acts (if at all) on the skin it reaches.

The category also includes dawn simulators, which brighten gradually in your bedroom before you wake. The best-studied dose is about 10,000 lux at your eyes for about 30 minutes soon after waking. A bright indoor room is only a few hundred lux, so a lamp that looks bright isn't necessarily delivering that dose.

How strong is the evidence?

Moderate evidence

For seasonal (winter) depression, randomized trials against dim-light or sham devices show a clear benefit: a 2020 meta-analysis of 19 trials found bright light beat placebo, and in one trial it matched fluoxetine. It has also beaten placebo in non-seasonal depression. The limits are study size and quality (mostly small trials with moderate-to-high risk of bias), and the evidence for jet lag, energy or general wellness is much thinner.

The claims you'll see, checked

Treats seasonal affective disorder (winter depression)

Holds up

The best-studied use: about 10,000 lux for 30 minutes each morning. In a Canadian trial it worked as well as fluoxetine and acted faster.

Helps non-seasonal depression

Holds up

In a placebo-controlled trial, light alone and light plus fluoxetine both beat placebo. The evidence base is smaller than for seasonal depression, and it belongs alongside care, not instead of it.

Dawn simulators treat winter low mood

Mixed

A meta-analysis pooled five small positive trials, but the evidence is thinner than for a light box.

Shifts your body clock for jet lag or late sleep timing

Mixed

Morning light moves your clock earlier and evening light later, which is solid physiology, but trials of light boxes for jet lag and sleep problems are few and mixed.

Blue-enriched light works better than white

Unproven

The key trials used white light; blue-enriched boxes haven't been shown to do better.

Any bright 'daylight' bulb or mood lamp will do

False

Trials used about 10,000 lux at the eyes for 30 minutes, or about 2,500 lux for 2 hours. Most lamps deliver far less at a normal sitting distance.

What to look for

  • 10,000 lux at a stated, practical distance (for example 40–60 cm, 16–24 in). A lamp that only reaches 10,000 lux a few centimetres from your face is a poor buy.
  • White light with UV filtered out. You don't need 'full-spectrum' or UV.
  • A lit surface large enough that small head movements don't take you out of the beam.
  • Flicker-free output and a stand that places the light slightly above eye level, angled down.
  • For a dawn simulator: a gradual brightening ramp (typically 30 minutes or more) and a light you can place near the bed.
  • A timer, so a morning session becomes a routine you keep.

What to skip

  • Colour-changing 'mood' lamps and ordinary daylight bulbs sold as therapy lights.
  • Blue-only or 'blue-enriched' premiums; they aren't shown to beat white light.
  • Energy, focus or 'productivity' claims for healthy people, which are barely tested.
  • Tiny lamps whose rated lux is only reached a few centimetres from the face.

How to use it

  • Use it within about an hour of waking: roughly 30 minutes at 10,000 lux, or as your clinician advises.
  • Sit at the distance where your box actually delivers 10,000 lux; check the manual.
  • Keep your eyes open with the light in view, slightly above and in front of you. Read or eat breakfast rather than staring into it.
  • If winter low mood returns every year, start as the days shorten and continue through the dark months.
  • Give it a couple of weeks. If you're not improving, or feel worse, see a clinician.

Who should be careful

  • See a clinician before starting if you have bipolar disorder: bright light can trigger hypomania or mania.
  • Check first if you have eye disease (such as macular degeneration or diabetic retinopathy), a light-sensitive condition, or take light-sensitising medicines.
  • Headache, eye strain, nausea or feeling wired are common at first and usually settle; shorten the session if they don't.
  • Depression is a medical condition. Use light alongside care, not instead of it, and get urgent help if you have thoughts of self-harm.
  • Avoid late-evening sessions unless advised, because they can push your sleep later.

The studies

Every citation is checked against its PubMed record.

  1. The Efficacy of Light Therapy in the Treatment of Seasonal Affective Disorder: A Meta-Analysis of Randomized Controlled Trials
    Pjrek E, Friedrich ME, Cambioli L, Dold M, Jäger F, Komorowski A, et al. · Psychotherapy and Psychosomatics · 2020 · Meta-analysis

    Across 19 randomized trials of bright light (at least 1,000 lux) against dim light or sham devices, light therapy reduced depression scores (SMD −0.37) and raised response rates (RR 1.42) in seasonal affective disorder; studies were small with moderate-to-high risk of bias.

  2. The Can-SAD study: a randomized controlled trial of the effectiveness of light therapy and fluoxetine in patients with winter seasonal affective disorder
    Lam RW, Levitt AJ, Levitan RD, Enns MW, Morehouse R, Michalak EE, et al. · American Journal of Psychiatry · 2006 · Randomized controlled trial

    In 96 patients with winter depression, 8 weeks of 10,000-lux light for 30 minutes each morning (plus a placebo pill) worked as well as fluoxetine (plus dim placebo light): 67% responded in both groups. Light worked faster and caused fewer side effects such as agitation and sleep disturbance.

  3. Efficacy of Bright Light Treatment, Fluoxetine, and the Combination in Patients With Nonseasonal Major Depressive Disorder: A Randomized Clinical Trial
    Lam RW, Levitt AJ, Levitan RD, Michalak EE, Cheung AH, Morehouse R, et al. · JAMA Psychiatry · 2016 · Randomized controlled trial

    In 122 adults with non-seasonal major depression, 8 weeks of morning 10,000-lux light beat an inactive placebo device, alone (effect size 0.80) and combined with fluoxetine (1.11); fluoxetine alone did not beat placebo.

  4. The efficacy of light therapy in the treatment of mood disorders: a review and meta-analysis of the evidence
    Golden RN, Gaynes BN, Ekstrom RD, Hamer RM, Jacobsen FM, Suppes T, et al. · American Journal of Psychiatry · 2005 · Meta-analysis

    Only 13% of studies met quality criteria. Among those, bright light (effect size 0.84) and dawn simulation (0.73) reduced symptoms of seasonal depression, and bright light helped non-seasonal depression (0.53); effects were similar to antidepressant drug trials.