Top doctors call for an end to daylight saving time: Three experts argue the once-a-year shift fuels a rise in the number of strokes and heart attacks

• The warning came from Vanderbilt University and the University of Pennsylvania
• Three doctors said research has demonstrated health harms of clock changes
• Europe has already decided to abolish daylight saving time within two years
• But in the US, whether to turn the clocks back is decided by individual states   

A team of doctors in the US has said daylight saving time should be ‘eliminated’ because it can damage people’s health.

They said shifting the clocks back and forth every year leads to a rise in the number of heart attacks and strokes and can affect children’s brain development.

Young children, the elderly, women and people with cancer appear to be more susceptible to the effects of the time shift.

Dr Beth Malow and Dr Kanika Bagai, from Vanderbilt University in Tennessee, and Dr Olivia Veatch from the University of Pennsylvania expressed their concerns in a journal.

Daylight saving currently pushes time forward an hour in spring, and pulls it back an hour in autumn, making sunrise later in summer and earlier in winter. 

Europe has already decided to abolish the procedure in two years’ time but in the US whether to use it is decided on a state-by-state basis. 

Researchers say the sleep disruption caused by turning the clocks backward and forward can affect people’s heart rate and blood pressure, which may increase their risk of having a heart attack or stroke (stock image)

The researchers wrote: ‘Transitions to DST [daylight saving time] have documented detrimental associations with the brain, specifically ischemic stroke, with the risk of myocardial infarction [heart attack] and well-being also affected.

‘A lower quality of sleep, shorter sleep duration, and decreased psychomotor vigilance have also been reported.

‘Additional studies are needed to understand the causes of these detrimental effects and the role of sleep deprivation and circadian disruption.

‘Based on these data, we advocate for the elimination of transitions to DST.’

There are growing calls from scientists and experts to change daylight saving time to try and reduce its effects on people’s health. 

Time changes mess with sleep schedules, a potential problem when so many people are already sleep deprived, says Dr Phyllis Zee, a sleep researcher at Northwestern Medicine in Chicago.

Research suggests that chronic sleep deprivation can increase levels of stress hormones that boost heart rate and blood pressure, and of chemicals that trigger inflammation.

Scientists have also found that heart attacks are more common in general in the morning, and that incident rates increase slightly on Mondays after clocks are moved forward in the spring, when people typically rise an hour earlier than normal.

That increased risk associated with the time change is mainly in people already vulnerable because of existing heart disease, said Barry Franklin, director of preventive cardiology and cardiac rehabilitation at Beaumont Health hospital in Royal Oak, Michigan.

Studies suggest that these people return to their baseline risk after the autumn time change.

Numerous studies have also linked the start of daylight saving time in the spring with a brief spike in car accidents, and with poor performance on tests of alertness, both likely due to sleep loss.

The research includes a German study published this year that found an increase in traffic fatalities in the week after the start of daylight saving time, but no such increase in the fall.

Till Roenneberg, a specialist at Ludwig-Maximilian University in Munich, Northwestern’s Dr Zee said: ‘If we want to improve human health, we should not fight against our body clock, and therefore we should abandon daylight saving time.’

Source: Associated Press 

The team made their comments in an editorial article in the journal JAMA Neurology, which is published by the American Medical Association.

Clock changes and ill health have been linked multiple times in the past and there have been growing calls to abandon daylight saving time altogether.

Europe will stop using DST from 2021, its Parliament decided this year, in a move which could affect the UK as well depending on legislation after Brexit.

In the US, whether people use daylight saving time varies from state to state.

The majority observe the tradition but Arizona and Hawaii, for example, do not.

Others are in various stages of testing its effects or considering sticking to one time zone.

In the UK daylight saving time – in which all time zones jumped forward an hour – this year ran from March to October, and in the US from March to November. 

In their editorial the Vanderbilt and Pennsylvania researchers said past research has found the risk of a stroke was ‘significantly’ higher for two days after the switch.

And a review of studies taking in more than 100,000 people found there was a five per cent increase in the number of heart attacks after the spring’s forward change.

These risk increases may be caused by people getting less sleep when the time changes in the middle of the night, which could increase heart rate and blood pressure.

People’s mental wellbeing has also been seen to get worse when the clocks change.

And studies on schoolchildren found they were more likely to become sleepy in the daytime and to sleep less at night, which could damage the development of their young brains.

The doctors added: ‘While it is unclear how disruptive a one-hour time change is to otherwise healthy individuals, it is possible that individuals with extreme manifestations of chronotype [morning/evening person] or circadian rhythm sleep-wake disorders, neurological disorders, or children and adolescents whose brains are still developing are more susceptible to the adverse health effects that occur following the DST transition.’

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