Bright light therapy for depression: A review of its effects on chronobiology and the autonomic nervous system

Abstract

Bright light therapy (BLT) is considered among the first-line treatments for seasonal affective disorder (SAD), yet a growing body of literature supports its use in other neuropsychiatric conditions including non-seasonal depression. Despite evidence of its antidepressant efficacy, clinical use of BLT remains highly variable internationally. In this article, we explore the autonomic effects of BLT and suggest that such effects may play a role in its antidepressant and chronotherapeutic properties. After providing a brief introduction on the clinical application of BLT, we review the chronobiological effects of BLT on depression and on the autonomic nervous system in depressed and non-depressed individuals with an emphasis on non-seasonal depression. Such a theory of autonomic modulation via BLT could serve to integrate aspects of recent work centered on alleviating allostatic load, the polyvagal theory, the neurovisceral integration model and emerging evidence on the roles of glutamate and gamma-hydroxybutyric acid (GABA).

Investigation of an Immediate Effect of Bright Light on Oxygen Consumption, Heart Rate, Cortisol, and α-Amylase in Seasonal Affective Disorder Subjects and Healthy Controls

“…Heart rate is usually slightly increased by light especially if the light is presented at night/early morning [reviewed in [5], [6]] [23]. In our study, the light was given late in the morning.…”

“…Heart rate and sympathetic nerve tone are increased immediately following a light intervention [reviewed in [5], [6]]. An effect of light on α-amylase, considered to be a marker of sympathetic nervous system activity [7,8], has been investigated, with negative results [9,10].…”

Light and smell stimulus protocol reduced negative frontal EEG asymmetry and improved mood

“…For example, light and smell have been demonstrated to affect mood and alleviate depression (for reviews see [9,37]) and in this study we set out to develop an integrated stimulation protocol that combined both light and smell in order to try to obtain increased benefit from any synergistic effects that might occur. Bright light therapy uses a constant light intensity presenting an unchanging stimulus to the retina and visual cortex.…”

Vitamin D for Depression with a Seasonal Pattern: an Effective Treatment Strategy

“…94 Light boxes are available for purchase and emit full spectrum bright light similar in composition to sunlight that exerts effect on chronobiology and autonomic nervous systems of depressed patients. 94 Light boxes filter out ultraviolet rays and require 20-60 minutes of visual exposure to 10,000 lux of cool-white fluorescent light daily during fall and winter seasons. 95,96 Bright light is safe with minimal side-effects that include eyestrain, headache, irritability, sleep disturbances and age-related macular degeneration.…”