Vital de Azevedo W.M. et al. - Photobiomodulation and Sleep Quality: A Systematic Review and Meta-Analysis

Among 240 participants across 5 randomized, placebo-controlled trials, photobiomodulation improved the Pittsburgh Sleep Quality Index score by 1.25 points (95% CI -2.38 to -0.11; p = 0.03). The confidence interval is wide, and its upper limit is close to indicating no effect, which limits the significance of the result.

What this study measured

Sleep quality is commonly measured using the Pittsburgh Sleep Quality Index, a questionnaire in which a lower score indicates better sleep. The authors used this criterion to evaluate photobiomodulation.

Five randomized clinical trials were included, involving a total of 240 participants. Each trial compared photobiomodulation to a sham device, which allows for partial control of the placebo effect. The analysis was conducted using a random-effects model, and heterogeneity among the studies was quantified.

Key Findings

The result is statistically significant but of moderate magnitude and not very precise.

• Mean difference on the Pittsburgh Index: -1.25 points (95% CI -2.38 to -0.11)
• Significance threshold reached: p = 0.03
• Heterogeneity across studies: I² = 36.2%, considered low to moderate
• Number of trials and participants: 5 randomized trials, 240 participants
• Comparator used in all trials: placebo group

The authors themselves point out that the width of the confidence interval reflects the limited precision of the estimate. The upper bound, −0.11 points, corresponds in practice to a virtually zero effect.

How photobiomodulation works for this indication

The proposed hypotheses focus on two mechanisms. The first is metabolic: the absorption of red and near-infrared light by mitochondria is thought to support cellular energy production, including in the brain when the light is applied transcranially. The second concerns the regulation of low-grade inflammation and oxidative stress, both of which have been associated with poorer sleep quality in the literature.

None of these mechanisms are directly tested in this meta-analysis. It is also important to distinguish between therapeutic photobiomodulation, which uses low intensities, and chronobiological light exposure used to reset the internal clock: these are two distinct approaches that are not based on the same principles.

Limits You Should Know

Five trials and 240 participants constitute a limited evidence base. A single large-scale study with conflicting results could alter the conclusion.

The authors note methodological heterogeneity among the protocols and imprecision in the estimates. They conclude that the data remain limited and call for larger, standardized trials to determine the optimal parameters, including wavelength, dose, and site of application. The meta-analysis also provides no information on the duration of the effect after treatment is discontinued, nor on the populations in which the benefit would be most pronounced.

What This Means in Practice

The evidence exists, but it is limited. It does not justify presenting photobiomodulation as a solution to sleep disorders, much less as an alternative to the management of chronic insomnia, for which cognitive-behavioral therapy remains the first-line treatment.

A persistent sleep disorder warrants medical evaluation, as it may indicate obstructive sleep apnea, an anxiety or depressive disorder, or an underlying medical condition. Photobiomodulation is not a substitute for this evaluation or for prescribed treatment.

Frequently Asked Questions

Does photobiomodulation really improve sleep?

In this meta-analysis, it was associated with a 1.25-point improvement in the Pittsburgh score compared with a placebo—a significant but imprecise result based on only 5 trials and 240 participants.

How many sessions does it take to see a result?

The protocols differ too much from one trial to another to establish a standard number of sessions. The authors explicitly call for standardized trials in this regard.

Can photobiomodulation be used as an alternative to treatment for insomnia?

No. The available data are too limited, and photobiomodulation is not a substitute for cognitive-behavioral therapy or prescribed treatment. A persistent sleep disorder should be evaluated by a healthcare professional.

Reference

Vital de Azevedo WM, de Souza K, Defante ML, Salgado ASI, Lopes-Martins RAB, Gomes da Silva S, Gonzalez-Lima F, Cardoso FDS. Photobiomodulation and sleep quality: systematic review and meta-analysis. Lasers in Medical Science, 2026. PMID 42322437. PubMed link

This summary is provided for informational purposes only and does not constitute medical advice. Photobiomodulation is not a substitute for prescribed treatment. Consult a healthcare professional.