Circadian lighting and sleep

Benedetti and colleagues found that circadian lighting in offices can improve how well people sleep at night. 

They “tested the effects of optimized dynamic daylight and electric lighting on circadian phase of melatonin, cortisol and skin temperatures in office workers. We equipped one office room with an automated controller for blinds and electric lighting, optimized for dynamic lighting (= Test room), and a second room without any automated control (= Reference room).

Young healthy participants (n = 34) spent five consecutive workdays in each room. . . . Vertical illuminance in the Test room was 1177 ± 562 photopic lux . . . which was 320 lux higher than in the Reference room. . . . Melanopic equivalent daylight (D65) illuminance was 931 ± 484 melanopic lux in the Test room and 730 ± 390 melanopic lux in the Reference room. . . .

The melatonin secretion onset and peripheral heat loss in the evening occurred significantly earlier [people were sleepy earlier] . . . in the Test compared to the Reference room.”

Marta Benedetti, Lenka Maierova, Christian Cajochen, Jean-Louis Scartezzini, and Mirjam Munch. 2022. “Optimized Office Lighting Advances Melatonin Phase and Peripheral Heat Loss Prior Bedtime.”  Scientific Reports, vol. 12, np. 4267, https://doi.org/10.1038/s41598-022-07522-8