DALLAS – March 14, 2019 – Ah, the first days of daylight saving, that time of year when our brains endure varying degrees of disorientation.
For those who rise for work at dawn, forwarding the clock a mere hour means being jolted awake in the dark by the morning alarm. Young children with early bedtimes deal with the confusion of being tucked in with the sun still shining.
These discomforts provide anecdotal evidence of the central role circadian rhythms play in regulating our mind and body. And though the one-hour change rarely causes serious health issues, an international debate is brewing over whether to abandon daylight saving due to scientific studies that document some startling consequences of disrupting our biological clocks.
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A European coalition is considering doing away with biannual time changes even as some U.S. states want to implement daylight saving year round for economic purposes.
While the pros and cons are weighed for each, one of the world’s leading experts on circadian rhythms says there should be no dispute about the negative health effects of delaying sunrise and sunset. UT Southwestern’s Dr. Joseph Takahashi, who discovered the first circadian gene in mammals (CLOCK), points out that desynchronized body clocks are linked to greater health risks such as obesity, heart attack, cancer, and depression.
“It is now well established that waking up even an hour earlier adds to stress on our body and sleep deprivation,” says Dr. Takahashi, a Howard Hughes Medical Institute Investigator. “Imagine what is happening in the brain and body when our circadian rhythms have to deal with bigger disruptions.”
Daylight saving – to the extreme
Such extreme circadian abnormalities occur in places like Kashgar, a remote city in far western China where people don’t see the sun rise until about 10:15 a.m. during some stretches of winter. They have to wait until nearly 10:30 p.m. for the sun to set during the early summer.
The unusual circumstance stems from China maintaining a single time zone for a land slightly wider than the continental U.S.
While multiple time zones shield Americans from harsher disruptions of their circadian rhythms, research shows people in western China face lower life expectancy compared to the country’s eastern population. The same study also found higher life expectancy and lower cancer rates for populations in the southeastern parts of European Russia.
In fact, research generally shows that cancer rates increase the farther west one lives in a time zone, where it is more likely people wake up in the dark. This includes populations in the United States.
“There may be multiple factors that contribute to these findings,” Dr. Takahashi says. “But many scientists believe the disruption of the optimal phasing of our circadian rhythms – the timing of our rhythms relative to the phase of the solar day-night cycle – is a prime culprit.”
Dr. Takahashi notes that people who work overnight shifts are also at a greater risk for cancer, in part because prolonged disturbances of the body’s clock weaken the immune system. In addition, abnormal rhythms have been tied to higher rates of depression and heart attack, in particular in the first few days of daylight saving.
Push for change
Daylight saving time was first adopted in the U.S. a century ago, a brief experiment during World War I that was resurrected several decades later.
The merits of the concept – originally rooted in energy conservation – are now being vaunted by some states’ lawmakers who want it implemented year round.
Voters in California last year passed a ballot initiative that authorizes the Legislature to seek federal approval to keep the state on daylight saving time. Florida has passed a similar resolution but is awaiting congressional approval.
The European Commission, the arm of the European Union tasked with proposing legislation, is also pushing a plan that would end biannual time changes. However, some nations disagree on whether to exclusively use daylight saving or standard time.
Supporters of the former say an extra hour of daylight year round would benefit businesses and allow students more time for exercise and outdoor activities after school.
However, the Society for Research on Biological Rhythms favors a perennial use of standard time to help people sleep earlier relative to their work times and reduce chronic social jetlag.
“Being on daylight saving time is the equivalent of residing on the extreme western edge of a time zone, which we now know has increased associations with health risks,” Dr. Takahashi says.
Other scientists point out that permanent daylight saving could have especially pronounced circadian disruptions for people living in a place like California. In the far northern stretches of the approximately 800-mile-long state, sunrise could be delayed until around 8:45 a.m. in late December. They predict this lack of morning light would present long-term public health risks.
Go East, young man?
Even without the prospect of permanent daylight saving, Americans still have much to deal with in these first few weeks of delayed sunrise.
And unfortunately, the best advice for avoiding disturbances to our body clocks may not be the most practical. One might move east and quit the overnight job. Or, the heck with daylight saving: Show up for work an hour late until the clock moves back in November.
For those individuals lacking such options, Dr. Takahashi suggests trying to keep a consistent sleep schedule and understanding that people have different chronotypes: lark and owl. The owl, the person who stays up later and sleeps later, tends to struggle with daylight saving time more than the lark, the early riser, he says.
“Since being an owl or a lark is in large part genetically influenced, the best way to deal with daylight saving time is to be self-aware of your chronotype,” Dr. Takahashi says. “Owls should realize that advancing their clock will be harder and make the proper preparations.”
Dr. Takahashi says the Munich Chronotype offers a simple questionnaire to self-assess chronotypes, and the National Sleep Foundation provides helpful information as well.
Dr. Takahashi is Chairman and Professor of Neuroscience at UT Southwestern, with the Peter O’Donnell Jr. Brain Institute at UT Southwestern, and a Howard Hughes Medical Institute Investigator, who holds the Loyd B. Sands Distinguished Chair in Neuroscience, and is the 2016 recipient of the Peter Farrell Prize in Sleep Medicine.
About UT Southwestern Medical Center
UT Southwestern, one of the premier academic medical centers in the nation, integrates pioneering biomedical research with exceptional clinical care and education. The institution’s faculty has received six Nobel Prizes, and includes 22 members of the National Academy of Sciences, 17 members of the National Academy of Medicine, and 15 Howard Hughes Medical Institute Investigators. The full-time faculty of more than 2,500 is responsible for groundbreaking medical advances and is committed to translating science-driven research quickly to new clinical treatments. UT Southwestern physicians provide care in about 80 specialties to more than 105,000 hospitalized patients, nearly 370,000 emergency room cases, and oversee approximately 3 million outpatient visits a year.