In addition to the hour less of sleep, there's also the threat of another, more serious disadvantage to daylight saving time. An American College of Cardiology study suggests the time change could result in more heart attacks. Scientists found that on the Monday after daylight saving time went into effect, there were 25 percent more heart attacks than on a standard Monday. They say these findings possibly mean people who are already vulnerable to heart disease may be at greater risk right after sudden time changes. Daylight saving time begins this Sunday at 2:00 a.m.