jones_supa writes: Having a good night's sleep seems to play a big part in people having heart attack risk. Switching over to daylight saving time, and hence losing one hour of sleep, raised the risk of having a heart attack the following Monday by 25 percent, compared to other Mondays during the year, according to a new U.S. study released on Saturday. By contrast, heart attack risk fell 21 percent later in the year, on the Tuesday after the clock was returned to standard time, and people got the extra hour of sleep. The not-so-subtle impact of moving the clock forward and backward was seen in a comparison of hospital admissions from a database of non-federal Michigan hospitals. It examined admissions before the start of daylight saving time and the Monday immediately after, for four consecutive years. Researchers cited limitations to the study, noting it was restricted to one state and heart attacks that required artery-opening procedures, such as stents.