Effects of Bright Light Exposure During Daytime on Peripheral Clock Gene Expression in Humans

The study, conducted on seven healthy men, explored the impact of bright light exposure on the expression of clock genes in hair follicular and root cells. It concluded that a single day of bright light exposure during daytime did not significantly alter the expression of most clock genes, such as Per1, Per2, Per3, Cry1, Cry2, Rev-erb-a (Nr1d1), and Dec1. However, there was a tendency for increased expression of Rev-erb-ß (Nr1d2) under bright light conditions. The findings imply that more prolonged exposure to bright light might be necessary to affect clock gene expression in humans. The study's small sample size and infrequent sampling may have limited its ability to detect minor gene expression changes.