Daily aspirin users may be better protected against heart disease or stroke if they take the blood-thinning pills before turning in at night, according to new research presented at the American Heart Association's (AHA) annual meeting in Dallas this week.

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Millions of Americans take a low-dose aspirin daily to help thin their blood and prevent the formation of clots, which can lead to heart attack or stroke. Such cardiovascular events are about three times more likely to occur in the morning, when blood pressure and platelet activity are at peak levels.

In the new study, researchers from Leiden University Medical Center in the Netherlands examined nearly 300 patients with heart disease who were taking aspirin to ward off a second heart attack.

During two separate three-month periods, half of the patients were instructed to take 100 milligrams of aspirin first thing in the morning, while the other half were told to take the drug right before bed.

The researchers found that morning platelet activity was lower when aspirin was taken at night, and patients did not suffer any additional side effects from the late dosage.

However, the study did not detect a difference in morning blood pressure levels between the two patient groups.

Lead study author Tobias Bonten says the "next step" will be to determine whether reduced platelet activity leads to fewer heart attacks and strokes. Until then, he says people should continue to take the aspiring when it is most convenient (Hellmich, USA Today, 11/19; O'Connor, "Well," New York Times, 11/19; Thompson, HealthDay, 11/19).