visible-light exposure delivered by a light box or comparable device
What it is, why people use it, the evidence, and what to know before trying it.
Bright light reaching the eyes signals intrinsically photosensitive retinal ganglion cells and can shift circadian timing. Morning exposure usually advances the sleep-wake rhythm, while evening exposure can delay it; timing, spectrum, distance and intensity all matter.
Mechanism evidence: human
Bright light is an established circadian intervention, but the best timing depends on the user's phase and goal. Evidence for insomnia shows improved wake-after-sleep-onset with substantial heterogeneity, not a universal benefit for every sleep outcome.
Confidence: moderate
Placement, electrical-device and medical precautions from the manual and reviewed sources.
Possible effects include eyestrain, headache, agitation, nausea and sleep disruption if mistimed. Bipolar disorder, retinal disease, migraine or photosensitising medicines warrant clinician input. Do not stare directly into the light; follow the device distance and timing instructions.
This review does not automatically apply to:
Public protocols that include Bright light therapy. Open one to see the full context and source.
Manufacturer guidance and observed protocol patterns, kept separate from evidence of benefit.
Session and timing patterns reported in public protocols; these are observations, not instructions. Private and hidden usage is excluded.
Continue into interventions that appear alongside this one.