Mayo Clinic Aspirin Dr. Virend Somers, is a Cardiologist from the Mayo Clinic, who is lead author of the report in the July 29, 2008 issue of the Journal of the American College of Cardiology. Most heart attacks occur in the day, generally between 6 A.M. and noon. Having one during the night, when the heart should be most at rest, means that something unusual happened. Somers and his colleagues have been working for a decade to show that sleep apnea is to blame. If you take an aspirin or a baby aspirin once a day, take it at night. The reason: Aspirin has a 24-hour "half-life"; therefore, if most heart attacks happen in the wee hours of the morning, the Aspirin would be strongest in your system. FYI, Aspirin lasts a really long time in your medicine chest for years, (when it gets old, it smells like vinegar)....