Moving to daylight saving time when spring comes is bad for our health – a doctor explains why this is worse than the fall time change.
On Sunday, March 12th, 2023 people in the U.S. will have to move their clocks ahead an hour according to the yearly practice of switching from standard time to daylight saving time, which causes disruption of daily activities that are reported on by media sources.
Lots of people don’t like having to change the clocks twice a year. In fact, almost two-thirds would rather get rid of this completely than keep changing their clocks back and forth (21% aren’t sure what to think).
Researchers are finding that when we move the clocks forward each March, it can cause bigger issues than a bit of inconvenience. It is linked to health problems like an increase in heart attacks and lack of sleep for teens. On the other hand, when we change back to standard time in fall, it’s not connected with negative health effects according to our research from 2020.
For the past five years, I have been looking into the upsides and downsides of changing the clocks twice a year. As a professor of neurology and pediatrics at Vanderbilt University Medical Center’s sleep division, I’ve learned that when we move the clocks forward in spring, it can affect people’s health not just when it happens but for up to eight months afterwards too.
Daylight Saving Time
Americans are not sure which they like better, keeping their clocks set ahead for Daylight Saving Time all year-round or setting them back to normal time all year.
Standard time on the clock is usually when the sun is directly above us at 12 o’clock. During daylight saving time, between March and November, the clock shifts earlier so that it will be light out an hour later in the morning and an hour later in the evening.
The light when we wake up in the morning helps us to stay alert and feel good. When people do not get enough sunlight during the winter months, doctors sometimes prescribe them using light boxes that mimic natural light to try and make them feel better.
Researchers are still trying to figure out why light makes us feel positive and improves our moods. It could be because of increased cortisol (a hormone that helps control stress) or the influence it has on our amygdala (the part of the brain related to emotions).
Teens may be consistently not getting enough sleep due to things like school, sports, and hanging out with friends. For example, lots of kids have to go to school at 8am or earlier. During daylight savings time when the sun rises late, this means that a bunch of young people have to get up and travel to school in complete darkness.
There are many good reasons to make sure everybody uses the same time all year round (called permanent standard time). At a hearing in March 2022, I talked about these reasons. The American Medical Association also said this would be a good idea and at the end of 2022 Mexico adopted it to save energy, help health, and make people more productive.
Daylight saving time gives us the extra hour of light in the evenings which is useful for activities like playing sports, going shopping or having dinner outside. However, this benefit comes at a price. The extended evening light delays the brain’s release of melatonin, which helps us fall asleep. This messes up our sleep and causes us to not get enough shut-eye overall.
In puberty, our bodies start to release a hormone called melatonin later at night. This helps us fall asleep but makes it harder for us teens to get enough sleep because of all the bright light around us in the evening. This change stays with us until our twenties.
Suffering the Consequences of Circadian Misalignment
Living in different parts of a time zone can affect how much sleep you get. For example, research suggests that people living on the western edge get light later in the morning and later in the evening than those living on the eastern edge, meaning they have less chance to sleep.
People living in the western edge of a time zone are more likely to be obese, have diabetes and heart disease, or get breast cancer. They also usually earn less money and need to spend more on healthcare. According some studies, these people may also get other types of cancer more often than others.
Scientists think that some health issues can be caused by both not sleeping enough and when the timing of our daily routines doesn’t match when the sun rises and sets. This is called ‘circadian misalignment’. To learn more about this, watch a video which goes back to 1895 to explain why we have Daylight Saving Time.
Examining the Effects and Benefits of Daylight Saving Time
During World War I and II, and during the time when energy was scarce in the 1970s, Congress decided to make Daylight Saving Time (DST) last longer. They thought that if it stayed light out for longer, people would use less electricity by not needing to turn on their lights as quickly. However, this wasn’t true because some people need to use more energy when it’s darker in the morning during winter and more energy is used for air conditioning at night in summer.
People sometimes say that daylight saving might help to lessen crime because there’s more light at the end of the day. Research has shown this is true, but it only decreases crime a tiny bit and its effects on people’s health are much more important than any benefits from lower crime rates.
After World War II, it was up to each state to decide when daylight saving time started and stopped. This caused a lot of problems with train schedules and safety, so in 1966 the United States Congress passed a law called the Uniform Time Act. This law said that daylight saving time should start on the last Sunday in April and end on the last Sunday in October. In 2007, Congress changed the rule so that daylight saving time now stretches from the second Sunday in March until the first Sunday in November – and this is still true today!
The Uniform Time Act lets different states and territories decide if they want to stay on Daylight Saving Time or not. Arizona, Hawaii, Puerto Rico, U.S. Virgin Islands, Northern Mariana Islands, Guam, and American Samoa all chose to stay on Standard Time forever.
Lots of states in America are thinking about what to do with the time change between Daylight Saving Time and Standard Time. Many states want to keep the same time all year long. More of these states are planning on keeping Standard Time; the percentage of them is going up from 15% to 31%.
Back in March 2022, the U.S. Senate wanted to make daylight saving time last forever but the House didn’t move forward with it. Then on March 1, 2023 a Senator from Florida named Marco Rubio proposed the same idea again.
More states are trying to stop the regular changes between Standard and Daylight Saving Time because people are seeing it has negative effects. It is now up to lawmakers to decide if they should end this time shift or keep either Standard or Daylight Saving Time.
