NeuropsychobiologyAug 4, 2011

Using Bright Light Therapy to Help Mood Disorders

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Mar 29, 2026

Abstract

Bright-light therapy (BLT) is established as the treatment of choice for seasonal affective disorder (SAD).

BLT has shown promise in treating several forms of non-seasonal depression, including chronic, antepartum, premenstrual, and bipolar depression.
Further systematic studies are warranted to better understand the efficacy of BLT for non-seasonal mood disorders.
The suprachiasmatic nucleus (SCN) serves as the primary regulator for circadian rhythms in humans.
Melatonin, synthesized in the pineal gland, plays a crucial role in internal clock functions and is influenced by light exposure.
Serotonin, a precursor to melatonin, is involved in regulating behaviors that fluctuate with seasonal changes.

Simplified

Bright-light therapy (BLT) is established as the treatment of choice for seasonal affective disorder/winter type (SAD). In the last two decades, the use of BLT has expanded beyond SAD: there is evidence for efficacy in chronic depression, antepartum depression, premenstrual depression, bipolar depression and disturbances of the sleep-wake cycle. Data on the usefulness of BLT in non-seasonal depression are promising; however, further systematic studies are still warranted. In this review, the authors present a comprehensive overview of the literature on BLT in mood disorders. The first part elucidates the neurobiology of circadian and seasonal adaptive mechanisms focusing on the suprachiasmatic nucleus (SCN), the indolamines melatonin and serotonin, and the chronobiology of mood disorders. The SCN is the primary oscillator in humans. Indolamines are known to transduce light signals into cells and organisms since early in evolution, and their role in signalling change of season is still preserved in humans: melatonin is synthesized primarily in the pineal gland and is the central hormone for internal clock circuitries. The melatonin precursor serotonin is known to modulate many behaviours that vary with season. The second part discusses the pathophysiology and clinical specifiers of SAD, which can be seen as a model disorder for chronobiological disturbances and the mechanism of action of BLT. In the third part, the mode of action, application, efficacy, tolerability and safety of BLT in SAD and other mood disorders are explored.

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Using Bright Light Therapy to Help Mood Disorders

Abstract

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