Abstract
Evening residential illumination possesses the capacity to impair sleep quality via the suppression of endogenous melatonin production, a process largely driven by short-wavelength (blue) light. In this investigation, we characterized the light emissions from 52 distinct examples across three common lamp technologies: light-emitting diodes (LED), incandescent, and compact fluorescent (CFL) lamps. To estimate the differential circadian impact of these sources, we determined the Melatonin Suppression Value (MSV), melanopic illuminance, and photopic illuminance for each. Our findings reveal that "cool" white LED (median 12.3% MSV) and "cool" white CFL (12.1% MSV) lamps induce considerably greater melatonin suppression than "warm" white LED (3.6%), "warm" white CFL (2.6%), or traditional incandescent (1.5%) lamps. As potential countermeasures, we examined the efficacy of tunable Correlated Color Temperature (CCT) lamps and "blue-light-filtering" (BLF) lenses. The four tunable LED lamps demonstrated a profound ability to mitigate circadian disruption, reducing estimated melatonin suppression from 10% at a 5700 K (cool white) setting to 0.1% at 2100 K (warm white). An analysis of eight BLF lenses identified variable performance; while six had moderate impacts compared to uncorrected vision, their benefit was limited relative to standard clear lenses. Only two BLF lenses, distinguished by a "brown" tint, proved highly effective, reducing estimated suppression to below 0.3%. These results suggest that cool white CFL and LED lamps may exert a greater disruptive influence on sleep physiology than other lamp types. Conversely, tunable lamps adjusted to warm settings and "brown"-tinted BLF lenses represent beneficial strategies for ameliorating this effect. (Detailed measurement methodologies are available in a previously published study, with supplementary calculations provided separately).