New York has joined the rally to “lock the clock,” or “ditch the switch” — ending the twice-a-year clock time change. Alabama, Arkansas, Florida, Nevada, Oregon and Washington have already passed such bills. Legislators in the Empire State propose to follow suit, making daylight savings time permanent.
But this will be bad for our health and well-being. A far better solution is to stop springing forward and falling back — in favor of permanent standard time.
We’ve been here before. In 1974, the United States decided to keep daylight saving time year-round to save energy. After one winter of dark mornings, the decision was reversed with a landslide vote.
Powerful lobby groups have their stands: retail argues we shop more when the evenings are light; TV executives prefer dark evenings. But the biology is clear: permanent daylight saving time is bad for our health.
The argument to support “locking the clock” is twofold. In the short term, research suggests there are more car crashes and more heart attacks, with reports of a 24 percent increase in heart attacks the Monday after clocks are changed. “Springing forward” has also been linked to an increase in workplace injuries and a drop in productivity. More broadly, there is a chronic misalignment between our internal biological time and our social schedules during the months that we are in daylight saving time (March through October) — which may impact our health in the long term.
Whatever choice we make, we don’t get more hours of daylight; we only shift when those hours occur. For more northerly states, this is of critical importance in the winter, when the days are short. In New York, sunrise is around 7 a.m. in December and sunset around 5 p.m. Under permanent daylight saving — which has been proposed for New York — sunrise would be around 8 a.m. and sunset around 6 p.m.
Humans have internal biological clocks that anticipate daily environmental changes. Many of our biological processes are carefully tuned to make best use of the daily rhythm of wake and sleep, light and dark. Cortisol, the awakening hormone, is released prior to waking and prepares the body for the anticipated physical demands of waking activity. Melatonin, the sleep-promoting hormone, is released prior to sleeping and prepares the body for the anticipated rest period.
But our internal biological clocks do not know the time. To make sure that our natural, biological, wake period coincides with the hours we want to be awake for work or school, we need light, and the right amount of light at the right times of day.
If we shift to permanent daylight saving time, the later sunrise in the winter will shift our natural wake and sleep times later. Chronic misalignment of our internal biological time with our social schedules is associated with obesity, type 2 diabetes, cardiovascular disease risk and cognitive decline. Later sleep-wake times have been linked to poorer health and well-being, including poor dietary habits, physical inactivity, and risk taking behaviors.
Late sleep timing is already a problem for adolescents who have to go to school early. Permanent daylight saving time will exacerbate the problem and the benefit for teens in school districts that have already delayed school start times will be lost.
Locking the clock will impact more than 19.5 million New Yorkers. Locking into daylight saving time will result in shifting sunrise and sunset later during the winter months. Yet research shows that those with later patterns of light exposure have poorer health outcomes and earn less. For our health, well-being, and the economy, we should move to permanent standard time.
Kohl Malone is an assistant professor at NYU Rory Meyers College of Nursing. Patterson is an associate professor of health behavior science at the University of Delaware. Skeldon is a professor of mathematics at the University of Surrey, UK.
