Switching permanently to daylight saving time is biologically harmful because it causes sunrise to occur too late in winter, which disrupts the circadian rhythm.

noli's read

Shelby Harris’s position aligns with the current consensus in chronobiology research. The American Academy of Sleep Medicine (AASM), in a 2020 position statement, emphasizes that permanent standard time is preferable for human health because it better aligns our internal clock with the natural light-dark cycle. Scientific evidence, particularly from observational studies, indicates that insufficient exposure to morning light and more light in the evening can desynchronize the circadian rhythm, impairing sleep quality and alertness. The historical argument mentioned refers to the United States’ 1974 experiment, where the implementation of permanent daylight saving time was quickly abandoned due to a decline in public support, though the specific reasons for this failure are multifactorial (road safety, perception of well-being). While the impact on the circadian rhythm is solidly documented, the exact magnitude of the long-term consequences for public health remains a subject of active debate among sleep experts. In short, science supports the idea that shifting morning light to the evening is problematic for our biological clock.

the sources

1. 1Blume C, Garbazza C, Spitschan M 2019
2. 2Brown TM et al. 2022