Permanent daylight saving time could be a public health time bomb

President Trump is pushing for the US Senate to make daylight saving time permanent, claiming it would benefit golfers and extend evening daylight. However, new Canadian research suggests that permanent daylight saving time could have serious negative health effects that outweigh the benefits. The Canadian Medical Association Journal published a paper reviewing evidence on the health impacts of permanent daylight saving time (pDST) as Canadian jurisdictions consider ending the clock changes.

The study found that permanent daylight saving time would prolong darkness in the winter mornings, which is detrimental to the human body's circadian rhythm. Circadian rhythms run on a 24.2-hour schedule, and morning light is crucial for regulating them. Prolonged darkness in the morning, caused by pDST, can negatively affect sleep, mood, education, and work productivity.

For instance, a study in the US found that residents in western time zones experienced an hour less sleep per week, which was associated with lower long-term earnings. Similar results were seen in a German study. Additionally, research in Florida showed a correlation between more morning sunlight and higher math and reading scores.

The authors of the Canadian study argue that the preponderance of health evidence favors standard time (pST) instead of permanent daylight saving time, as sleep and chronobiology societies worldwide recommend. Despite the scientific consensus, the US Senate passed a bill to make daylight saving time permanent in 2022, and despite resistance, President Trump even posted the personal cellphone number of a Republican holdout on social media.