Researchers from the University of Oulu in Finland have found that staying to the same bedtime can reduce the risk of major cardiovascular problems, such as a heart attack or a stroke. The researchers measured sleep behavior activity for 3,231 individuals at the age of 46 and compared participants to groups of regular, fairly regular, and irregular sleep habits. The data showed that those in the irregular group showed double the risk for a serious cardiac event over the next decade compared to regular sleepers. The study also found that more variability in the sleep'midpoint' (halfway between bedtime and wake up) was linked to worse heart health. However, the risk association only showed up for those who got less than an average amount of sleep (just under eight hours) each night.