It’s nearly that time of the year again: the end of daylight saving, when Americans push their clocks back and rejoice at the gained hour of sleep—or mourn the lost hour of sunlight in the afternoon.
This system’s twice-a-year transitions have become increasingly unpopular. Scientists have been calling attention to the damaging effects of the time changes—which include a general reduction in mental and physical well-being, as well as a potential increased risk of serious complications, such as strokes and heart attacks, soon after the shifts. There is also evidence of increases in traffic fatalities and harmful medical errors shortly following when clocks are moved forward in the spring.
In many countries, this might be the one of the last instances in which people make the adjustment. Governments around the world have been in discussions about scrapping the seasonal clock changes and sticking to one time—either permanent standard time or permanent daylight saving. In the U.S., many states are considering, or have already passed, legislation to adopt one of the two. Hawaii and most of Arizona decided to adopt just standard time more than 50 years ago. Last year the European Parliament voted to abolish the time shifts, but the member states of the European Union have yet to agree on how to implement the decision.
Beth Malow, a professor of neurology and pediatrics at Vanderbilt University, spoke with Scientific American about the health effects of this timekeeping practice and what should replace it.
[An edited transcript of the interview follows.]
The end of daylight saving time is fast approaching. Generally speaking, how disruptive are the transitions to and from daylight saving to physical and mental well-being?
There’s a lot of variability in what people experience. Some people have shared with me that, for example, they might have a child with autism, and for two or three months after the transition, they feel like things are just not right with their child’s sleep. People also tell me they just feel out of sync for a while. Other people may deal with the change more easily. It’s similar to when we travel [from the U.S.] to Europe. Some people are affected by jet lag more than others.
The one thing I will say is that people think, “Well, it’s only an hour, so it’s not a big deal. It’s kind of like traveling from Nashville, [Tenn.], to New York [City]—going from Central to Eastern time.” But [daylight saving] really isn’t that. It’s a misalignment of your biological rhythms, or circadian rhythms, for eight months out of the year.
You wrote a commentary in JAMA Neurology last year that discusses some medical complications—such as cardiovascular problems and stroke—associated with the transitions. Can you talk a bit about how daylight saving changes can increase the risk for these kinds of events?
We don’t know the actual mechanism because these are epidemiological studies, where there are large numbers of people, and [researchers] observe the stroke rate or heart attack rate increase