Skip to nav Skip to content

Saturday most of the U.S. will “spring forward” as daylight saving time once again takes effect. While many relate the time change to longer days, more daylight and summer fun, doctors express some concern with the time shift’s effect on our health, particularly our hearts.

Losing an hour of a sleep as we spring forward may not seem like a big deal, but according to a study published in Open Heart, heart attacks jump by 25 percent the day after daylight saving time starts.

Dr. Roohi Ismail-Khan, medical oncologist

Dr. Roohi Ismail-Khan, a medical oncologist who provides care for cancer patients in the cardio-oncology and survivorship programs at Moffitt Cancer Center, says there are a number of reasons why heart attacks tend to spike the day after daylight saving time begins. One explanation is an increase in stress hormones. Lack of sleep stresses the body. She says periods of stress cause the body to increase inflammatory mediators, which affects the heart. For example, a person may have an underlying heart condition and the inflammatory mediators caused by stress can set off a heart attack.

“We know that people in Western societies are chronically sleep deprived and the average sleep duration decreased from nine to seven-and-a-half hours during the 20th century,” said Ismail-Khan.

Monday, not surprisingly, is the day of the week associated with the highest risk of acute myocardial infarction. Ismail-Khan said that the mental stress of starting a new workweek and the increase in activity could be why.

“Adding sleep deprivation in the spring from daylight saving time can compound this phenomenon as it happens on a Sunday morning, and Monday is already the most stressful day of the week,” she said.

Another reason we see more heart attacks following daylight saving time is due to a disruption in circadian rhythm, or our body’s internal clock. A study published in the journal Nature suggests that levels of a protein which controls the heart's rhythm fluctuate through the day. As the body’s chemistry changes throughout the day, it can affect the risk of heart attack. Daylight saving time has a jet lag type of effect on the body, which is a result of the body getting out of sync. Changing time zones or working overnights also put people at a greater risk of heart attack.

Springing forward may have other risks for women. Women who suffered a miscarriage and are undergoing in vitro fertilization showed higher miscarriage rates if embryo transfers were conducted within 21 days of the start of daylight saving time compared to those whose transfers were conducted the rest of the year. The study found no link between miscarriage rates and the fall time change.

Plus, preliminary research presented at the 2016 American Academy of Neurology's annual meeting found that stroke rates in Finland are 8% higher, on average, in the two days following both time changes—spring and fall—compared to the two weeks before or after.

It is not just health that’s impacted by Daylight saving time; work productivity also seems to suffer. A study in the Journal of Applied Psychology suggests that sleep-deprived employees spend more time "cyberloafing," or using the Internet for personal use while pretending to do work. 

But it isn’t all bad news. Changing the clocks may actually be beneficial for those suffering from depression.

A study published in Epidemiology found no change in the number of people diagnosed with depression as we spring forward but found more people diagnosed when we fall back. Scientists believe it may have something to do with the amount of daylight you are exposed to and its impact on mood.

Regardless of where we are instructed to set our clocks, sleep is an important factor for our health. Planning for adequate and quality sleep each night is key for improved health.