A study by Swedish researchers has found that the extra hour of sleep that the daylight savings time gives could prevent some people from having a heart attack. The research based on heart attacks in Sweden found that lack of sufficient sleep could adversely affect cardiovascular health and may even result in an increased likelihood of having a heart attack.

The study found that the heart attack risk dropped in the fall during the first week when the clocks were set back giving people an extra hour of sleep. The heart attack rate increased in the first week of spring when the clocks were reset again, this time giving them one hour less of sleep.

Sleep deprivation can increase heart attack chances as it increases the blood pressure and heart rate which can in turn lead to a tendency to form dangerous clots while chronic stress may induce abnormalities in heart function.

The study conducted by Drs. Imre Janszky of the Karolinska Institute and Rickard Ljung of the National Board of Health and Welfare also found this increased risk more pronounced in women over men. People under the age of 65 were more likely to be affected than those over as the older people often are retired and have an easy schedule.

Published in the New England Journal of Medicine the study also noted that there was a 5 % increase in heart attacks with a 6 % surge on Monday and Wednesday and a 10 % increase on Tuesday. Mondays become difficult days as it’s the work week beginning, a fact that previous studies have uncovered as well, showing deaths from heart attacks increased on a Monday as compared to other week days.

Daylight savings time affects 1.5 billion people worldwide when they turn their clocks forward in the spring and backward in fall.

The study authors suggest that people likely to be affected should try to avoid sudden changes in their biological rhythms and people who work more than the optimal 40 hours weekly should try to get two days of rest a month and get enough sleep.