Time’s up

In reality, changing the clocks doesn’t create or destroy daylight. It only changes what we call it. If you want more daylight in the winter, you need to move closer to the equator.

Changing the clocks twice a year is a nuisance. It’s also unhealthy.

“The switch itself does real harm. In the days after we spring forward, heart attacks rise. One analysis found a 24 percent jump in heart attacks on the Monday after the change. Strokes, traffic crashes, and workplace accidents climb, too. Ending the switch is worth doing. The only question is which time we keep.”

But locking in Daylight Savings Time isn’t the answer.

“. . . morning light and evening light are not interchangeable. Our bodies run on internal clocks that are set by the sun, not the clock on the wall. Morning light is the master signal: It resets our internal clocks each day and tells the brain to trigger a surge of cortisol. Cortisol, a hormone released by the adrenal glands, is the body’s built-in wake-up call that primes the body for activity by raising heart rate and blood pressure, and releasing blood sugar into the bloodstream for energy.

“Because our internal clocks run slightly longer than 24 hours, they depend on this daily reset and it works best in the first few hours after we wake. Permanent daylight saving time would move clock time an hour ahead of sun time. A December sunrise in Boston would slip past 8 a.m., and past 9 a.m. in parts of the country like Indianapolis, long after most people have started their commute or school day. Thus, our internal clocks would drift out of step with our work and school schedules.”

Permanent DST is especially problematic for adolescents.

“Adolescents, whose biological clocks naturally run late, would be hauled to school before their brains are ready to learn. As a high school nurse, I saw the consequences of this in a district spanning a large geographic area — where 7:30 a.m. start times meant bleary-eyed teens were boarding school buses as early as 6 a.m. Forced awakening during critical REM-rich sleep in the early morning impairs memory consolidation, mood regulation, and executive functioning. It undermines academic performance and is linked to poor mental health.

“The fix for those 6 a.m. bus stops, some argue, is later bells, not standard time. But we need both. Later school start times give teens back sleep their biology demands, and standard time keeps that gain real. Under permanent daylight saving time, an 8:30 a.m. bell would feel like 7:30 by the sun, quietly erasing years of hard-won progress.”

As long as humans insist on inhabiting the northern latitudes, there’s no perfect medium. But permanent Standard Time would be better than permanent DST.

https://www.bostonglobe.com/2026/10/19/opinion/daylight-saving-time-biological-clocks/