Why daylight saving time is unhealthy – a neurologist explains | Kiowa County Press

Changing clocks twice a year can be more than just a half-yearly inconvenience. Carol Yepes/Moment via Getty Images

Beth Ann Malow, Vanderbilt University

As Americans prepare to put their clocks forward one hour in mid-March, I prepare for the annual ritual of media stories on disruptions to daily routines caused by the transition from winter time to summer time.

About a third of Americans say they don’t look forward to these semi-annual daylight saving time changes. An overwhelming majority of 63% to 16% would like to eliminate completely.

But the effects go beyond mere inconvenience. Researchers find that “rushing” each March is linked to serious negative health effects.

An illustration of two clocks illustrating daylight saving time changes: falling backwards and jumping forwards.
At 2 a.m. on Sunday, March 13, 2022, the clocks move forward one hour. They fall back at 2 a.m. on Sunday, November 6, 2022. iam2mai/iStock via Getty Images Plus

I am a professor of neurology and pediatrics at Vanderbilt University Medical Center in Nashville, Tennessee, and director of our sleep division. In one comment 2020 for the journal JAMA Neurology, my co-authors and I reviewed the evidence linking the annual change to daylight saving time and increased hits, heart attacks and teenage sleep deprivation.

Based on a large body of research, my colleagues and I believe that the science establishing these links is sound and that the evidence supports the adoption of permanent standard time nationwide – as I testified at a recent congressional hearing.

Lack of sleep, poor health

“Flip” – switching from daylight saving time to winter time each November by turning clocks back one hour – is relatively benign. While some people may feel out of balance and need a few weeks to recover, research has not linked it to serious health impacts.

However, jumping forward is harder on the body. This is because the time of our clock is off by one hour; in other words, it looks like it’s 7 a.m. even though our clocks say it’s 8 a.m. So it’s a permanent switch to morning light for nearly eight months – not just on changeover day or a few weeks after. This is particularly noteworthy because morning light is valuable in helping to set the body’s natural rhythms: it wakes us up and improves alertness.

Although the exact reasons are not yet known, it may be due to the effects of light on the increase cortisol levelsa hormone that modulates stress response or the effect of light on tonsilpart of the brain involved in emotions.

In contrast, exposure to light later in the evening delays the brain’s release of melatonin, the hormone that promotes sleepiness. It can interfere with sleep and cause us to sleep less overall, and the effect can last even after most people get used to losing an hour of sleep at the start of daylight saving time.

Since puberty also causes melatonin to be released later at night, which means teens have a delay in the natural cue that helps them fall asleep, teens are particularly sensitive to sleep disorders from the extended evening light of summer time. This change in melatonin during puberty lasts into your twenties.

Teenagers can also be chronically sleep deprived due to schedules of school, sports, and social activities. For example, many children start school around 8 am or sooner. This means that during summer time many young people get up and go to school in complete darkness.

The “western edge” effect

Geography can also make a difference in how daylight saving time affects people. A study has shown that people living at the western end of a time zone, who get light later in the morning and light later in the evening, slept less than their counterparts to the east of a time zone.

This study found that residents of the Western Outskirts had higher rates of obesity, diabetes, heart disease and breast cancer, as well as lower per capita income and higher health care costs. Other research has shown that rates of some other cancers are higher at the western end of a time zone.

Scientists believe that these health problems could result from a combination of chronic sleep deprivation and “circadian misalignment”. Circadian misalignment refers to a time lag between our biological rhythms and the outside world. In other words, the rhythm of daily work, school, or sleep routines is based on the clock, rather than sunrise and sunset.

This video dives deeper – back to 1895 – into the history of daylight saving time.

A brief history of daylight saving time

Congress instituted daylight saving time during World War I and again during World War II, and again during the energy crisis of the early 1970s. The idea was that having more light later in the afternoon would save energy by decreasing the need for electric lighting. This idea has since been turned out to be largely inaccurateas heating needs can increase in the morning in winter, while cooling needs can also increase in the late afternoon in summer.

Another argument in favor of daylight saving time has been that crime rate deposit with more light at the end of the day. Although it has been proven, the change is very small and health effects seem to outweigh lower crime rates.

After World War II, it was left to state governments to set the start and end dates for DST. Because this created many railroad scheduling and safety issues, Congress passed the Uniform Time Act in 1966. This act set the national DST dates for the last Sunday in April to the last Sunday in October.

In 2007, Congress amended the Uniform Time Act to extend daylight saving time from the second Sunday in March to the first Sunday in November, dates that remain in effect today.

However, the law allows states and territories to opt out of daylight saving time. Arizona and Hawaii are on permanent standard time, as well as Puerto Rico, the US Virgin Islands, the Northern Mariana Islands, Guam and American Samoa. Today, many other states are considering whether to stop step back and leap forward.

The question then becomes: should they choose permanent daylight saving time or permanent standard time?

The solid arguments in favor of permanent standard time

Americans are divided on whether they prefer permanent daylight saving time Where permanent standard time. However, my colleagues and I believe that the health-related science for establishing the permanent standard time is sound.

Standard time is closest to natural daylight, with the sun directly overhead at or near noon. In contrast, during daylight saving time from March to November, daylight is unnaturally shifted an hour later.

Based on abundant evidence that daylight saving time is unnatural and unhealthy, I believe we should abolish daylight saving time and adopt permanent standard time.

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The conversation

Beth Ann MalowProfessor of Neurology and Pediatrics, Vanderbilt University

This article is republished from The conversation under Creative Commons license. Read it original article.

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