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Sleep experts: daylight saving time has long-term brain effects

Nov. 4, 2019, 2:40 PM

The annual transition to and from daylight saving time (DST) has clinical implications that last longer than the days where clocks “fall back” or “spring forward.”

Sleep experts published a JAMA Neurology commentary in which they recap large epidemiological studies to advocate for ending the practice. Photo/iStock

Changes in sleep patterns that stem from clock transitions can alter the epigenetics of the core genes in the circadian clock. Over time, DST eliminates bright morning light that critically synchronizes biologic clocks. Transition seasons are associated with increased risk of heart attack and ischemic stroke, as well as other negative effects of partial sleep deprivation. Average sleep duration shrinks by 15 to 20 minutes for adults during DST transitions, which may increase the risk of fatal accidents.

To raise awareness of the health impacts from clock transitions — which change when the body gets light — sleep experts from Vanderbilt University Medical Center (VUMC) published a JAMA Neurology commentary in which they recap large epidemiological studies to advocate for ending the practice.

People think the one-hour transition is no big deal, that they can get over this in a day but what they don’t realize is their biological clock is out of sync, said Beth Ann Malow, MD, Burry Chair in Cognitive Childhood Development, and professor of Neurology and Pediatrics in the Sleep Disorders Division at VUMC.

“It’s not one hour twice a year. It’s a misalignment of our biologic clocks for eight months of the year. When we talk about DST and the relationship to light we are talking about profound impacts on the biological clock, which is a structure rooted in the brain. It impacts brain functions such as sleep-wake patterns and daytime alertness,” said Malow.

Malow is the corresponding author alongside Kanika Bagai, MD, MSCI,  associate professor of Neurology at VUMC’s Sleep Disorders Division, and Olivia J. Veatch, MS, PhD, from the Center for Sleep and Circadian Neurobiology at the Perelman School of Medicine at the University of Pennsylvania.

Some people may have more flexible circadian rhythms and adjust quickly while others are more sensitive. Malow, an expert on autism and sleep, said that the transition impacts some children with autism for weeks or months.

While the sleep and circadian communities believe returning to standard time may be more biologically appropriate, gaining political buy-in for a nationwide change remains a challenge. State legislation is “all over the map,” with some states considering a return to standard time and others in favor of permanent DST. Tennessee has passed legislation supporting permanent DST, although such a change would require action from the U.S. Congress.

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