Americans can expect a potential disruption to their sleep schedule on March 9 as this year's first Daylight Savings Time approaches. While people are generally mixed about changing the clocks twice a year, springing forward for one additional hour of sunlight, has shown to pose risks to our cardiovascular health. 

“Historically, there have been several studies that have observed an increase in cardiovascular events, like heart attacks, in the days following the 'Spring forward' daylight savings time shift,” said Graham McGinnis, assistant professor in the Department of Kinesiology and Nutrition Sciences, housed within UNLV’s School of Integrated Health Sciences.

McGinnis is a chronobiologist who studies sleep disruption and how it affects our health. His current grant from the National Institutes of Health allows him to research the effects of social jet lag and how it contributes to cardiovascular disease.

“Our bodies are composed of finely tuned time-keeping mechanisms that help keep us in sync with our environment, and when our timing gets thrown off, the body can suffer some consequences until we are realigned,” he said. “We are all familiar with these feelings if we've worked a night shift, or if we have travelled across time zones. But we also get to experience this change en masse during the daylight savings time transitions when we 'Fall back' and 'Spring forward.'”

According to McGinnis, the springing forward of the clocks causes two disruptions that can elicit stress on the cardiovascular system: a disturbance in our circadian rhythm and losing one hour of sleep.

“No matter how small that shift may seem, several groups have found that there is a small but significant increase in heart attacks in the days following the Spring time change when we lose an hour of sleep, and a reduction in heart attacks during the Fall time change when we get an extra hour of sleep,” he said. “This highlights the protective role of sleep for heart health.”

A proposed bill to remove Nevada from Daylight Savings Time is currently being considered by the Nevada State Legislature. 

While the concerns around Daylight Savings Time are valid, McGinnis said that the minimal one-hour time change combined with the twice-a-year frequency pale in comparison to how daily sleep-hygiene decisions, as well as other health-related behaviors like diet and exercise, may impact cardiovascular health. In particular, his research focuses on the impacts of social jet lag on cardiovascular and metabolic health.

“People experience social jet lag when there is a misalignment between the schedules they keep on weekends and weekdays. For example, if a person has to wake up early on weekdays to make it to work on time, but prefers to sleep in, and/or stay out late on weekends, they would have social jet lag," he said. "Data from very large cohorts suggest that about 80% of the population has at least one hour of social jet lag, but many people shift their schedules by much more than that.

“If we were to think of an example where you go sleep at 10 p.m. and wake up at 6 a.m. on weekdays but go to sleep at midnight and wake up at 8 a.m. on weekends, that is two hours of social jet lag, double the magnitude of the shift during Daylight Savings Time. The particularly impactful part is that people generally do this every week, not just twice a year. It would be kind of like ‘Falling back’ on Friday, and ‘Springing forward’ on Monday, every week.”

Tips to ease the burden of Springing forward

McGinnis encourages others to shift their sleep and dietary behaviors in advance of the impending time change in order to minimize disruption, though the effects on cardiovascular health during Daylight Savings Time have not been tested.

“First, continue healthy behaviors. Try to get a healthy amount of sleep in the days leading up to the time change, approximately 7-to-8 hours for adults. Eat a healthy diet and avoid late night meals or snacking, which can negatively impact your circadian rhythm and reduce sleep quality. Also, avoid caffeine and alcohol late in the day as this also disturbs sleep,” he said.

“Secondly, if you can, start trying to shift some of those healthy behaviors in the days leading up to the time change. This can help your body by incrementally moving towards our new time instead of doing it in one day. Our body's timing system is most sensitive to light, food and exercise, and we can use those cues to make the time change easier. For example, try to avoid excessive light at night, including screens, as we prepare for the time change. Get plenty of morning sunlight, or maybe some morning exercise. This can help tune our brain's time-keeping system to the new time.”