Efficacy and ocular safety of bright light therapy lamps

The optical radiation safety of various seasonal affective disorder (SAD) treatment lamps, sunrise simulators and daylight bulbs available on the UK market have been assessed using recognised guidelines. An analysis is included of the photometry of circadian entrainment by bright light therapy, with a justification for a melanopsin-based action spectrum for treatment efficacy. Parameters relating to both efficacy and phototoxicity risk, which are potentially relevant to bright light therapy treatment regimes, are considered. Unpredictable variations are highlighted which lead to the conclusion that several relevant photometric variables of treatment lamps need to be characterised to predict efficacy and potential hazards.