Literature Sharing | Home Lighting Color Temperature and Melatonin Suppression

【Introduction】

Evening exposure to artificial residential lighting has become a daily reality in modern households. While indoor illumination provides comfort and productivity, growing scientific evidence shows that certain lighting types can significantly suppress melatonin secretion and disrupt circadian rhythm regulation. The dominant biological driver behind this disruption is short-wavelength blue light, commonly emitted by cool white LED and CFL lamps. To better understand how different home lighting technologies affect melatonin suppression, a recent study systematically measured 52 lighting samples across LED, incandescent, and compact fluorescent (CFL) categories. The research further evaluated tunable color temperature lamps and blue-light-filtering (BLF) lenses as potential countermeasures, providing valuable insight for evening lighting design.

Source:Sci Rep. 2026.  PMID: 41565717  DOI: 10.1038/s41598-025-29882-7

【Study Design and Experimental Conditions】

The research analyzed light emissions from 52 distinct lighting samples across three common household lamp technologies, including light-emitting diode (LED) lamps, incandescent lamps, and compact fluorescent (CFL) lamps. To estimate the differential circadian impact of each lighting type, three key metrics were measured, including the Melatonin Suppression Value (MSV) for estimating the suppressive impact on melatonin, melanopic illuminance for measuring the circadian-relevant light dose, and photopic illuminance for measuring perceived brightness. In addition to standard lamp evaluation, the study also assessed four tunable Correlated Color Temperature (CCT) LED lamps across multiple color temperature settings, as well as eight blue-light-filtering (BLF) lenses compared against standard clear lenses. This multi-component design allowed the research to evaluate both the source-level impact of lighting and downstream filtering interventions.

【Impact of Lamp Type on Melatonin Suppression】

The analysis revealed substantial differences in melatonin suppression based on lamp technology and color temperature. Cool white LED lamps produced a median MSV of 12.3%, while cool white CFL lamps produced a median MSV of 12.1%. In contrast, warm white LED lamps produced a much lower MSV of 3.6%, warm white CFL lamps produced an even lower MSV of 2.6%, and traditional incandescent lamps showed the lowest impact at only 1.5%. These findings indicate that cool white LED and CFL lamps cause approximately three to eight times more melatonin suppression than warm-tone lighting alternatives, suggesting that lamp color temperature plays a decisive role in evening circadian impact, with cool white sources representing the strongest suppressive influence.

【Effects of Tunable Color Temperature Lamps】

The four tunable CCT LED lamps demonstrated a strong ability to mitigate circadian disruption when adjusted to warmer settings. At 5700 K (cool white), estimated melatonin suppression reached approximately 10%, while at 2100 K (warm white), estimated melatonin suppression dropped to as low as 0.1%. This reflects an approximately 100-fold reduction in circadian impact simply by adjusting the lamp's color temperature. These results highlight that warm-tuned lighting environments can dramatically minimize melatonin suppression, making tunable lamps a highly effective tool for healthier evening illumination.

【Effects of Blue-Light-Filtering Lenses】

The study also analyzed eight BLF lenses, with notably variable performance across products. Six BLF lenses showed only moderate effects compared to uncorrected vision, and their benefit was limited when compared to standard clear lenses. Only two BLF lenses with a brown tint were highly effective, reducing estimated melatonin suppression to below 0.3%. This indicates that BLF lenses offer inconsistent protection, and that addressing blue light exposure at the lighting source level by using warm or tunable lamps tends to be a more reliable strategy than relying on lens-based filtering alone.

【Practical Implications for Evening Lighting】

The findings provide clear, evidence-based guidance for evening home lighting design. Cool white LED and CFL lamps above 4000K should be minimized in evening environments, as warm white lighting below 3000K is significantly less disruptive to circadian rhythm. Tunable CCT lamps adjusted to warm settings around 2100K offer the strongest melatonin protection, while brown-tinted BLF lenses can serve as a supplementary tool, though lens-based protection alone is generally limited. Overall, evening lighting strategy should prioritize warm-tone, low-intensity illumination, especially in bedrooms and relaxation areas. By selecting lighting designed with circadian-friendly principles, households can meaningfully reduce nighttime melatonin suppression and support healthier sleep patterns.