Heart attacks and other risks of daylight savings

RESEARCH HAS FOUND SPRINGING FORWARD CAN HAVE ADVERSE EFFECTS ON OUR HEALTH

Even the modest sleep deprivation and “circadian misalignment” triggered by this weekend’s shift to daylight saving time appear sufficient to increase the risk of heart attacks by as much as nearly 30 per cent.

Italian researchers offered that warning in a recent paper on the possible heart risks of the biannual clock change, “especially in the first week after the spring shift.”

Here’s a sampling of some of the research on the potential impact on body and mind of what many critics consider the “lunacy” of daylight saving time, which begins in most of Canada at 2 a.m. on Sunday, when clocks move forward an hour.

A SPIKE IN THE NUMBER AND TIMING OF HEART ATTACKS

“For most people, changing the time — even if only by 1 h (hour) — may produce tiredness as a small inconvenience. Other people, however, can have more serious consequences,” researchers from the University of Ferrara wrote in a study published in the journal Internal and Emergency Medicine.

Studies have shown an association between sleep and heart attacks. Short (less than six hours) of sleep has been associated with high blood pressure, diabetes, obesity and even premature death. When sleep is disrupted we tend to eat more calories and burn fewer of them. One small study has shown even a single night of disrupted sleep is enough to increase insulin resistance.

Heart attacks have numerous triggers — blizzards, natural disasters, and, for the working population, Monday mornings, possibly due to the stress of starting a new week, higher blood pressure and higher catecholamine levels, the hormones involved in the “fightor-flight” response.

According to the Italian team, Monday is also a critical day for Takotsubo cardiomyopathy, socalled “broken heart syndrome,” a sudden, temporary weakening of the heart muscle thought caused by sudden emotional stress.

The Italians reviewed the available literature on daylight saving time and heart attack and found seven studies, five conducted in Europe and two in the U.S, accounting for a total of 87,994 cases. All showed an association with an increased frequency of heart attack, with increases ranging from four to 29 per cent. Three found a higher incidence of heart attacks on the Monday after the time change.

All the studies were observational, meaning they can’t prove cause and effect. And it was only true for the spring shift, when clocks spring forward an hour to inject more sunlight into the evenings.

However, “our body prefers a longer than a shorter day,” said co-author Dr. Roberto Manfredini, the same way travelling several time zones to the east causes worse jet lag than flying west. “A similar pattern has been suggested for DST transitions," Manfredini said.

Our natural, free-running circadian rhythm that controls the body’s sense of day and night and when to eat and sleep also regulates metabolism in the heart and other organs. In particularly sensitive people, the hour of sleep lost may increase heart rate, blood pressure, stress levels and chemicals that promote inflammation.

“One day (Sunday) is clearly insufficient to become accustomed to waking an hour earlier in the morning,” Manfredini and colleagues wrote. Until DST is abolished, they suggest a smoother approach: move bedtime one hour a few days prior to the clock change to limit the effects of sleep deprivation and “take care in exposing oneself to abrupt changes of temperature in the immediate postshift days,” meaning don’t underdress just because the days are longer and brighter. Cold weather can constrict vessels and blood flow to the heart, once again potentially triggering heart attacks in susceptible people. So, earlier to bed, and wear scarves, hats and gloves.

In an interview with Healthyde- bate.ca’s Paul Taylor, cardiologist Dennis Ko of Toronto’s Sunnybrook Health Sciences Centre said the association between daylight saving time and heart attacks is likely real, but also likely small, and only meaningful for those with underlying heart conditions.

WHAT ABOUT STROKE?

A study presented at the American Academy of Neurology’s annual meeting in Vancouver in 2016 found the overall rate of hospital admissions for ischemic stroke — when a clot in the arteries blocks blood flow to the brain — was eight per cent higher during the first two days after a daylight saving time transition, compared to either two weeks before, or two weeks after the switch.

SLEEPY JUDGES ARE CRANKY JUDGES

In a 2017 study, a University of Washington and University of Virginia team looked at legal sentences handed down by U.S federal courts between 1992 and 2003. Sentences given on the Monday after the switch to daylight savings time were about five per cent longer than those given on the previous and following Monday, supporting their hypothesis that "judges doled out longer sentences when they were sleep deprived,” the authors wrote in Psychological Science.

LOST SLEEP ALSO MAKES US SLACKERS

A study by Penn State University researchers found the switch to daylight saving time increases that “productivity-draining endeavour” known as cyberloafing — checking personal emails or visiting websites on work time. Researchers performed a quasi-experiment by looking at archival data on the aggregate internet search behaviour of people in more than 200 of the largest metropolitan areas in the U.S. web searches related to entertainment rose the Monday after the clock shift when compared to the Monday before, and the second Monday after.