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Dr. Karin Johnson: Health and safety impacts of “springing forward”

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On Sunday, March 13, it will be time to “spring forward” one hour for daylight saving time.

On Tuesday, March 8, SciLine interviewed: Dr. Karin Johnson, a sleep medicine specialist and an associate professor of neurology at UMass Chan Medical School – Baystate. See the footage and transcript from the interview below, or select ‘Contents’ on the left to skip to specific questions.

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KARIN JOHNSON: My name is Dr. Karin Johnson. I’m an associate professor of neurology at UMass Chan Medical School – Baystate in Springfield, Massachusetts. And I’m a sleep specialist that works at Baystate Medical Center in Springfield, Mass.

Interview with SciLine

What is the human biological clock?


KARIN JOHNSON: So, we all have a clock that is primarily set by the sun. And it—we have a clock in all of our cells. But we have the master clock in our brain. And so, it controls the rest of these cells by putting out hormones and other neurotransmitters that align all these cells to work together. So, this affects how our heart beats and the rate of our heartbeat, how our stomach digests and gets all of these systems working together to make us healthier.

How does springing forward affect sleep, the brain, and the body?


KARIN JOHNSON: When we do that clock change, the new schedule, our activities, the artificial light, does not change our body’s clocks. So, when we look at the hormone levels, specifically cortisol, that follow our clock, we see only a two-minute change in our internal body clock time, even though we have an hour change in the sun time. And so, all of our internal clocks then are misaligned and so are not matching up with our activities. And so, if our body wants to eat at 8 a.m., but our—we actually are eating at the essential 7 a.m., then we’re not going to align things, like our acid levels. And that can lead to symptoms of irritable bowel syndrome or – and can lead to other metabolic problems, like increased risk of obesity. And changes in our heart control can lead to increased risk for heart attacks and strokes. So, it’s really important for our clocks to align with our body’s activities. And that’s what we lose when we are changing those clocks.

How can the switch negatively impact people’s health, productivity, and safety, such as at worksites and on the road?


KARIN JOHNSON: When we have the clock change, our bodies don’t adjust the clocks. And also, especially in the springtime, we tend to lose sleep because we lose that hour. So, we end up with a mix of both sleep deprivation, as well as misalignment of the clocks. And so those two factors come together and are typically at the worst in that first week to two after that clock change. And so, what studies have found is increased risk—especially, again, after the spring change, where we lose that hour and go onto daylight savings time, which is more misaligned with our own internal clock – that we have more heart attacks, more strokes, more arrhythmias like atrial fibrillation.

There are more fatal car crashes in the week after time change, and then also other things like more missed medical appointments. We have more medical errors that occur in that time period, so it is not only—and then more sleep complaints. So, people often just feel more tired and don’t perform as well at work. So, it’s a mix of, again, that sleep deprivation effect, as well as that misalignment effect that’s going to be at the most right at the time of time change.

What does the research say about proposals to stop the twice-yearly clock change by permanently adopting either standard time or daylight saving time?


KARIN JOHNSON: We are very much in favor of stopping time change because we know there are these big effects twice a year that are at their worst right as we change the time. However, it is really important—the decision of which time we change to. And so, there’s permanent standard time—that’s the time where the sun is overhead at noon for more of the year and more of the time—or daylight savings time, which is shifted by an hour from that sun time. And some parts of time zones—because they want to stay in sort of aligned with places like New York City—have extended and are even more off from that time change. So, the western ends of the time zone are particularly misaligned by over an hour from that ideal time. So, the best time for our health to prevent things like obesity and diabetes, to make our heart healthier and have less heart attacks and to have us sleeping better and longer is to be more aligned with the sun time, which is the standard time.

How have expectations changed around energy savings due to daylight saving time?


KARIN JOHNSON: Back when this was, you know, first decided to go on daylight savings time, it was thought to save energy. And again, the thought would be that we would have more light in the evening, and so people would be more active during that time of day and use less light. Now where we are is lights have become a lot more efficient. We use a lot more electricity for other things, whether it’s our phones and computers, but also primarily heating and cooling. And on daylight savings time, when it’s lighter later, we tend to have cooler mornings, so we tend to need more heat to warm up the house or the office to get things warm enough. And when it’s lighter later, it’s also hotter later, and so people are using more air conditioning.

What has research shown about energy use during daylight saving time?


KARIN JOHNSON: More recent studies—one of the biggest was in Indiana when they changed some of their time zones in 2007, so they were really able to see what is the effect of being on one time zone versus another—they found that the heating and cooling costs actually were more on permanent daylight savings time than on standard time. So again, it’s really less clear that we’re saving energy. Additionally, because it’s expected that people sleep less by 19 minutes on average if they’re on daylight savings time, that’s about 1% of our day, and so it wouldn’t be surprising if we actually spend about 1% more energy because people tend to spend more energy, whether it’s through driving or using electronics and other things while they’re awake than while they’re asleep.

Who is most affected by time changes?


KARIN JOHNSON: One thing that you always want to think about with a policy change is there’s always going to be some winners and some losers. So, people argue that having it lighter later, people are going to have more time to be outside or to spend more money or hang out on Main Street and buy things. But the people that are most at risk from these changes, both from health consequences as well as consequences that might affect things like their productivity and salary, are the people that have to get up for work or school by 7 a.m. While on average people lose about 19 minutes of sleep for every day on daylight savings time, people who get up early lose about 36 minutes of sleep. And that might seem like a little time, but that actually is a big effect.

And so, the people that tend to have those early work schedules are disproportionately minorities, disproportionately people with lower socioeconomic economic status. And also, the other people that are going to be the most affected are those who tend to have a later schedule and like to sleep in later, and the classic group of people are teenagers. And so, we’re putting that young population, who are at the prime of their life in terms of learning, in terms of getting good behaviors, making good decisions, at a particularly risky period and putting them at more risk from sleep deprivation, which we know affects academic performance, future, you know, attainment of salaries and different aspects like that. So, those are the at-risk people that are going to be most affected by a decision to make us get up earlier each day.

What should reporters know about the current national conversation around daylight saving time?

(Posted March 8, 2022 | Download Video)

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