Every March, on the second Sunday, we turn the clocks ahead one hour to begin daylight saving time, which gives us one more hour of light during the evening when the weather is warmest. And every November, on the first Sunday, we turn the clocks back to resume permanent standard time.
The disruptions to sleep patterns and the collective grogginess in the week or so afterward are discomforts that we’ve gotten used to. But does it have to stay that way?
In this Q&A, Andrew Varga, MD, PhD, a neuroscientist and physician at the Mount Sinai Respiratory Institute Integrative Sleep Center, discusses the pros and cons of keeping the clocks set permanently at daylight savings time or permanent standard time.
“The bottom line is that we can’t change the amount of daylight we get,” he says. “But we, as a community, can decide when we want those hours of daylight to occur.”
Andrew W. Varga, MD, PhD
What are the health issues surrounding switching to daylight saving time?
Changing the clocks twice a year creates lots of problems, especially at the point of the time change. There are increased spikes and incidents of adverse health outcomes at those times of year in the spring and fall when we make the time change.
Twice a year, everyone is forced to make a dramatic adjustment in their circadian rhythm, which is your internal biological clock that governs key functions, such as your sleep/wake cycle, eating habits, digestion, and body temperature. It’s been documented that making the change has a number of adverse consequences, such as an increase in heart attacks and cardiovascular incidents at those times. And because people are sleepy, there’s a spike in the statistics in auto accidents, as well.
What are the alternatives?
It seems everybody is on the same page that we should stick with one thing, and not change it. But there are two camps—one is for making daylight saving time permanent, and the other is to stick with permanent standard time year-round.
The American Academy of Sleep Medicine believes we should stick with permanent standard time, which is what we observe in the fall and winter. They argue that permanent standard time is more in line with people’s natural circadian rhythms.
It’s worth remembering that we can’t change the amount of daylight in June or December, we can only decide where we want that light to be. The people who are proponents of permanent daylight saving time like the fact that in June you have light as late as 8:30 pm. If we were to change it to permanent standard time, you’d only have daylight until 7:30 pm. But you would gain it in the morning, so sunrise would be around 4:30 am instead of 5:30 am.
What would happen if we changed to permanent daylight saving time?
If we shifted to permanent daylight saving time in the winter, we would gain an hour of daylight in the afternoon but lose it in the morning. The sun would set at 5:30 pm instead of 4:30 pm, but it wouldn’t rise until 8:30 am. So most people would be getting up and commuting to work in the dark, and children would be going to school in the dark.
In addition, the further north you are, the more drastic the differences in the amount of light. For example, in Minnesota, the sun would rise about 20 minutes later than in New York City, at almost 9 am. In Miami, the sun would rise about a half hour earlier than New York—at about 8 am.
The United States did experiment during the energy crisis with switching to permanent daylight saving time. Congress passed the Emergency Daylight Saving Time Energy Conservation Act in December 1973, and at first, the public didn’t react that much. But as the consequences began to be felt over the course of the year, the public outcry was significant, and the law was repealed by the fall of 1974.
What is the argument for making standard time permanent?
Most medical authorities agree that sticking to standard time would be best from a health and safety standpoint. The American Academy of Sleep Medicine has released a position paper that says the twice-a-year time change “incurs significant public health and safety risks, including increased risk of adverse cardiovascular events, mood disorders, and motor vehicle crashes.” The paper makes an argument that standard time year-round would best align with human circadian rhythms. The time that we habitually wake up, go to bed, and do certain activities, such as commuting, is more in line with standard time.
It’s interesting to note that Arizona stays on permanent standard time and has done so since 1968. I’m not aware of any data that shows whether they are realizing any health benefits. However, they are routinely not included in national traffic accident statistics due to this fact.