Not only do you get an extra hour of sleep this weekend, you also have a lower risk for heart attack. Researchers in Sweden studied the impact time change has on heart attack rates. They found chances went up dramatically the first three days after the time change in the spring, yet the risk dropped in the fall. Experts say losing an hour of sleep in the spring is the likely cause behind the increased risk for heart attack. The protective effect in the fall was only seen on the first Monday after the time change.