Photobiomodulation and Mood and Anxiety Disorders: A Balanced Review

Photobiomodulation (PBM) refers to a range of therapies that use low-level light—typically red or near-infrared—to influence cellular function. Red light therapy (RLT) is one of the most commonly recognized forms of PBM, though other modalities, such as low-level laser therapy (LLLT) and near-infrared (NIR) light treatments, also fall under this umbrella. PBM is drawing growing interest for its wide-ranging potential to support various aspects of health and well-being. Best known for its dermatological applications, emerging literature also suggests that it can be leveraged to support mental and neurocognitive health (Woźniak et al., 2025).

With its roots in mitochondrial science and cellular metabolism, PBM has attracted interest among functional medicine practitioners and patients alike. But how strong is the evidence for its use in mood and anxiety disorders?

What Is Photobiomodulation?

Photobiomodulation uses low-level red or near-infrared light, usually in the 600–1100 nm range, applied to areas like the scalp or body. This light is absorbed by the mitochondria—the energy-producing parts of cells—and can help boost energy production, reduce oxidative stress, and support healthy cell function  (Glass, 2021).

PBM is non-invasive and does not carry the same risks as ultraviolet light exposure. Its effects are being studied not only in dermatology and sports medicine but increasingly in psychiatry and neurology.

The Mitochondrial and Neuroinflammatory Connection

Evidence continues to accumulate linking mitochondrial dysfunction, oxidative stress, and neuroinflammation to mood disorders, including major depressive disorder (MDD) and bipolar disorder (Ni et al., 2022). PBM’s potential to target these upstream mechanisms positions it as a promising adjunctive tool in functional psychiatry.

In addition to mitochondrial effects, PBM may improve regional cerebral blood flow, promote neurogenesis, and influence brain network connectivity (Nairuz et al., 2024). Similar mechanisms are also implicated in the therapeutic effects of antidepressants and neuromodulation techniques like TMS.

Clinical Evidence to Date

While the research base is still developing, early findings are encouraging. A 2019 systematic review in the Journal of Affective Disorders showed positive outcomes for transcranial PBM in people with depression (Caldieraro & Cassano, 2019).

More recently, a 2024 systematic review and meta-analysis of randomized controlled trials in Frontiers in Psychiatry concluded that PBM is an effective treatment for depression (Ji et al., 2024). In a 2019 pilot study, researchers found that PBM may be a promising alternative treatment for patients with generalized anxiety (Maiello et al., 2019).

However, it should be noted that larger trials with standardized protocols are needed. Dosing parameters—such as wavelength, duration, and frequency—are not yet well established.

Clinical Considerations for Photobiomodulation

When it comes to using photobiomodulation to support mood or cognitive health, most of the research so far has focused on applying light directly to the head—a method known as transcranial PBM. Early findings suggest it’s generally well-tolerated, with only mild, short-term side effects reported in most studies. That said, results can vary depending on how the treatment is delivered. The dose, duration, and type of device used all seem to matter, and not all devices are created equal.

It’s also worth noting that while PBM shows promise, it’s still considered an experimental treatment in psychiatry. It hasn’t been approved by the FDA for mood or anxiety disorders, and more high-quality research is needed before it can be widely recommended.

PBM in a Broader Treatment Framework

In functional psychiatry, interventions are ideally selected based on individual biochemistry, root cause analysis, and an integrative model of care. PBM may serve as one component of a broader strategy that includes nutrition, sleep regulation, targeted supplementation, psychotherapy, and—in some cases—medication.

At present, PBM is best viewed as a complementary modality rather than a standalone treatment. It may hold particular relevance in cases of treatment resistance, chronic fatigue, or neuroinflammatory burden—contexts in which mitochondrial support is a therapeutic priority.

Conclusion

PBM represents an emerging area of interest in the treatment of mood and anxiety disorders. While early research is promising, clinical application should be cautious and evidence-informed. As the field evolves, PBM may become a valuable tool in the functional psychiatry toolkit—but further investigation is essential to clarify its role, optimize its use, and understand its limitations.

Want to learn more about photobiomodulation and how to incorporate this into patient treatment? Check out the webinar, Exploring Transcranial Photobiomodulation & its Applications, and our comprehensive course, Photobiomodulation for Brain Health!