The switch to daylight savings or summer time is already known to be much more difficult for evening types than for morning types.
“There are already reports of higher incidence of heart attacks following the switch to summer time,” says von Schantz. “And we have to remember that even a small additional risk is multiplied by more than 1.3 billion people who experience this shift every year. I think we need to seriously consider whether the suggested benefits outweigh these risks.”
How the study worked
For the study, researchers from the University of Surrey and Northwestern University examined the link between an individual’s natural inclination toward mornings or evenings and their risk of mortality. They asked 433,268 participants, age 38 to 73 years, if they are a “definite morning type” a “moderate morning type” a “moderate evening type” or a “definite evening type.” Deaths in the sample were tracked up to six and half years later.
The study was supported by the University of Surrey Institute of Advanced Studies Santander fellowship and the National Institute of Diabetes and Digestive and Kidney Diseases grant R01DK095207 from the National Institutes of Health.