Does adding morning light therapy help CBT-insomnia?
STUDY: Schmid SR et al, Journal of Sleep Research 2026
STUDY TYPE: Randomized, placebo-controlled trial
FUNDING: EUCOR — The European Campus EVTZ; Swiss National Science Foundation
Background
Cognitive behavioral therapy for insomnia (CBT-I) is the first-line treatment for insomnia, but about 25% of patients don’t respond and full remission occurs in only 40%. Morning lightbox reduces insomnia in small trials, and this study tested the two techniques together.
The Study
- 42 adults with insomnia disorder, mean age 52, mostly female
- Randomized to four weeks of CBT-I plus active light therapy or CBT-I plus a dim placebo lamp; both used at home for 20 minutes each morning
- Insomnia severity measured at post-treatment and 3-month follow-up
Results
Remission rates were greater with light therapy (29% vs 10%), but the difference wasn’t statistically significant in this small sample.
Daytime sleepiness (Epworth Sleepiness Scale [ESS]) did improve significantly with light treatment. At three-month follow-up, ESS in the light therapy group dropped from 7.7 to 4.9, while the placebo group barely moved (8.0 to 7.3). That’s a clinically meaningful difference, roughly double the two-to-three-point threshold considered significant in sleep disorders.
Side Effects
No safety concerns were reported.
Limitations
Small trial. Light treatment not monitored and not blinded.
Practice Implications
- Light therapy is a promising addition for insomnia. However, earlier trials found more success with a different protocol (using it 30 minutes very early, around 5 am). Here are lightboxes that work.
- Patients who do not want to sit under a lightbox can try an easier method: dawn simulator.
- Separate trials have found that blue-light blocking glasses enhance CBT-I.
—Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
