Warm or cool LEDs? What the research says about sleep
Sleep scientists agree that evening light should be dim and low in blue, and warm white LEDs make that easy. Newer lab research on LEDs and the cells' power plants is early but worth knowing.
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A 2022 expert consensus says evening light, from 3 hours before bed, should be dim and low in blue; warm white 2700–3000K LEDs meet that at normal home brightness.
A cool 6500K LED gives more than twice the body-clock signal of a warm white one at the same brightness.
Lab studies link the blue in LEDs, and their lack of red and infrared light, to weaker mitochondria, but the human evidence so far is small and limited to tests of vision.