Daylight saving linked to heart attack

As we struggle to adjust to daylight saving time, it’s important to recognise how it impacts our bodies.

In Australia, daylight saving changes occur in New South Wales, South Australia, Tasmania, the Australian Capital Territory, Victoria and Norfolk Island. It is not observed in the other states and territories.

From 2am on the first Sunday of October, clocks are put forward an hour. At 3am daylight saving time on the first Sunday of April, clocks are put back an hour.

For four consecutive years, an American study has analysed the impact of daylight saving on heart health. The study analysed a database from non-federal Michigan hospitals, looking at around 42,000 admissions from the beginning of daylight saving and the week prior, and compared them to the admissions in the week following adjustment back to normal time.

The study found that on the Monday after losing an hour of sleep to daylight saving, the risk of having a heart attack increased by 24 per cent.

Study lead Dr Amneet Sandu, a cardiologist at the University of Colorado in Denver, noted that historically heart attacks are more likely to occur on a Monday morning. This may be because of changes in the sleep cycle, or from the stress of starting a new work week. 

Dr Sandu presented his findings to the American College of Cardiology in Washington, stating, “With daylight saving time, all of this is compounded by one less hour of sleep.”

Interestingly, the study found that the overall number of heart attacks in the week after moving the clock forward didn’t change. While the rate of heart attacks spiked on the Monday, it then reduced for the rest of the week. This may be because factors trigger patients who were already at high risk to have a heart attack earlier in the week than they otherwise would.

Dr Sandu noted, “If we can identify days when there may be surges in heart attacks, we can be ready to better care for our patients.” He recommended increasing the number of staff available to care for patients on these days.

However, the study does have limitations. It only examined the cases of heart attack that required artery opening procedures, excluding patients who had died prior to hospital admission. The study also only analyses the data of hospitals in Michigan. However, the link between heart attacks and daylight saving changes has been validated by a number of other studies.

Another study, presented in the American Academy of Neurology’s 2016 conference, found a link between transitions to daylight saving time and increased risk of ischaemic stroke. Other studies have found an increase in fatal road accidents on the Monday following a switch to daylight saving time, as well as an increased rate of workplace injuries.

So, what does this mean for your health? The most important thing to learn from these studies is just how important your sleep cycle is for your health. If learning about this study made you concerned about your own heart health, consult your doctor. It is always better to be safe than sorry. If you find Monday mornings particularly stressful, it’s likely your body does too. It may be time to make positive lifestyle changes that support your sleep cycle and help to reduce stress.


Have you noticed daylight saving affecting your sleep cycle? How do you manage the change?

If you enjoy our content, don’t keep it to yourself. Share our free eNews with your friends and encourage them to sign up.

Related articles:

Disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.

Written by Liv Gardiner

Writer and editor with interests in travel, lifestyle, health, wellbeing, astrology and the enivornment.

Leave a Reply

Health benefits of oats

World’s rudest place names