The Monday after we lose an hour in the switch to daylight saving time is bad for heart attacks. What about switching back to standard time?

Published: November 1, 2021 | Updated: October 13, 2022

Daylight saving time gets blamed for as much as a 24% spike in heart attacks the Monday after we move clocks ahead in the spring. But does moving clocks back in the fall have the same effect?

There’s good news. The same study that found the big increase in the spring heart attacks found the converse to hold up in the fall. There were 21% fewer heart attacks on the Tuesday after switching back to standard time. The number of heart attacks on the Monday following the fall time change was in line with other Mondays.

While there was a spike in the spring and a drop in the fall, the number of heart attacks evened out to normal over the course of the week following time changes, according to the study conducted in 2014.

The study looked at data from Michigan for the weeks following spring and fall time changes between 2010 and 2013.