A new study of sleep and bedtime habits has a clear message for those wanting to lower their risk of major cardiovascular problems (such as a heart attack or a stroke): Stick to a regular bedtime. While health studies often focus on the quality and duration of our sleep , here researchers from the University of Oulu in Finland found that getting to bed at the same time each night can be significant as well if you aren't getting more than eight hours of sleep. The researchers measured sleep