Content type: Research paper
In addition to making you more alert during the day, improving your mood and sleep, the blue in bright morning sunlight acts as a countermeasure or antidote to some of the damaging health effects of artificial light at night.
It doesn’t give you a free pass to use artificial light at night without bad health effects, but it reinforces your circadian system so that exposure to a blast of artificial light at night doesn’t hurt you as much.
Cite: Münch M, Nowozin C, Regente J, Bes F, De Zeeuw J, Hädel S, Wahnschaffe A, Kunz D. Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase. Neuropsychobiology. 2016;74(4):207-218. doi: 10.1159/000477093. Epub 2017 Jun 22. PMID: 28637029.