Martin Young, Ph.D.Many people may groan about losing an hour of sleep this spring, but there may be a more serious reason to be mindful of daylight saving time.
Martin Young, Ph.D., in the University of Alabama at Birmingham Division of Cardiovascular Disease, says springing forward one hour is associated not only with increased accidents, but also increased risk of heart attacks, particularly for people with a history of heart disease.
“Moving the clocks ahead one hour in March is associated with a 10 percent to 24 percent increase in the risk of having a heart attack the following Monday and to some degree Tuesday,” Young said.
Young says many factors may contribute to the increased risk of heart attacks following the beginning of daylight saving time, including loss of one hour of sleep and a misalignment of our internal clock. Every cell in the human body has an internal time mechanism, also known as a circadian clock, which is responsible for driving rhythms in biological processes. These rhythms follow a roughly 24-hour cycle, responding to changes in light and darkness in an organism’s environment.
When these clocks are interrupted or experience a sudden change, there can be several different health effects.
“Going from a sleeping state to waking is already a stressful event in the body,” he said. “When we have an abrupt change, like losing an hour of sleep with daylight saving time, our internal clocks don’t have enough time to reset various biological processes.”
Sleep deprivation
Individuals who are sleep-deprived generally have an increased risk of cardiometabolic diseases, such as obesity, diabetes and heart disease. Sleep deprivation can also alter other body processes, including inflammatory responses and blood clotting, which may contribute to heart attack risk.
A person’s reaction to sleep deprivation and the time change also depends on whether he or she is a morning person or a night owl. Night owls have a much more difficult time with springing forward.
Circadian disruption, immune function and clotting
Immune cells also have a clock, and normal immune responses depend greatly on the time of day. A time shift like daylight saving puts the body in a pro-inflammatory state, which can worsen heart disease outcomes.
When a person wakes up in the morning, the body has a natural peak in its ability to clot. Conversely, clotting potential generally decreases during sleep. However, immediately following acute sleep-deprivation, the ability to form a clot is amplified.
“The sleep period is one time when the cardiovascular system should not be challenged,” Young said.
Young also says changing time zones and jet lag can cause circadian desynchrony, and increase the risk of heart attacks. It is important to note that these circadian disruptions will increase risk of a heart attack, primarily in susceptible individuals who often have underlying illnesses.
According to Young, each organ resets its internal clock differently: The brain uses light cues, and the liver responds to meal timing. But the heart receives a mix of these signals, which can create confusion and disrupt normal function.
Young says daylight saving time likely impacts more than the heart, since all cells in the body possess internal clocks.
To ease the transition, he suggests dividing up the one-hour loss over the course of the weekend. For example, if you usually wake up at 6 a.m. on a weekday, then set your alarm for 5:40 a.m. Saturday, for 6:20 a.m. (new time) Sunday and for 6 a.m. Monday. In addition, eat a decent-sized breakfast, then go outside in the sunlight and exercise, as appropriate and as recommended by your doctor.
“Doing all of this will help reset the central clock in the brain that reacts to changes in light/dark cycles, and the peripheral clocks — the ones everywhere else, including the one in the heart — that react to food intake and physical activity,” Young said. “This will enable your body to naturally sync with the change in the environment, which may lessen your chance of adverse health issues on Monday.”