Fall back: How the time change can affect health
Daylight saving time, which began on Sunday in most of the United States, has long been touted as a way to save energy by reducing the need for nighttime lighting. But recent studies have shown that our bodies’ internal clocks don’t spring forward as easily as our watches.
When our circadian rhythms — which regulate physical, mental and behavioral changes based on a 24-hour day/night cycle — are offset, it can negatively impact our health, affecting everything from our chances of developing cancer to an increase in depression and obesity.
Xiaoyong Yang, assistant professor of comparative medicine and of cellular and molecular physiology, studies the ways in which light affects the body’s circadian rhythms and metabolism.
Metabolism drives all biological processes and is controlled by diet as well as the light/dark cycle. When the body’s metabolism is thrown off, it can lead to a range of diseases, including diabetes, obesity, cancer, cardiovascular disease, neurodegenerative disease and aging. Yang’s research shows that circadian rhythm disorder is likely one of culprits of these diseases.
“It generally takes a few days to adjust the body’s clock to daylight saving time, during which people may experience physiological and psychological challenges,” Yang said, adding that, as a result, incidents of suicide or heart attack seem to be increased. While Yang suggests that daylight saving time may have devastating effects on individuals with pre-existing health problems, an understanding of how it affects healthy individuals remains elusive.
“My take on this is that the effect may be negligible because our bodies usually cope well with slight environmental changes. A one-hour shift may not a big deal,” he said. “Major health concerns should be focused on groups with severe disruption of circadian rhythms, such as rotating shift workers and frequent flyers.”
Yong Zhu, associate professor of epidemiology and public health, studies the link between cancer and circadian rhythms, and believes that repeated interruptions to these natural rhythms play a significant role in breast, prostate and lung cancer, non-Hodgkin’s lymphoma and other forms of the disease.
Last year, Zhu and his team discovered the underlying biological mechanism — namely, changes to the CLOCK gene, which is a key component of the molecular circadian regulatory system — that links nighttime shift work to as much as a 50% increase in women’s susceptibility to breast cancer.
“Our 24-hour oscillation is an ancient adaptation to the rotation of the Earth and can influence many biochemical, physiological, and behavioral processes in our body,” Zhu said. “Disruptions of these critical rhythms may have a profound influence on our health, and might increase an individual’s risk of cancer if this one-hour shift affects someone’s regular working schedule at night or regular sleeping pattern.”
But Zhu adds that the risk for the average person is low. “Most people should not worry about the one-hour change of daylight saving time because it should have little impact on our health.”
— By Suzanne Taylor Muzzin
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Suzanne Taylor Muzzin: suzanne.taylormuzzin@yale.edu, 203-432-8555