HealthDay News — Taking aspirin at bedtime rather than in the morning is associated with a reduction in platelet reactivity, according to a study presented at the American Heart Association’s 2013 Scientific Sessions.

“Because higher platelet activity contributes to a higher risk of acute heart events, this simple intervention — switching aspirin intake from morning to bedtime — could be beneficial for the millions of patients with heart disease who take aspirin on a daily basis,” Tobias Bonten, MD, from the Leiden University Medical Center in the Netherlands, said in a statement.

He and colleagues conducted a randomized cross-over trial from September 2011 to April 2013 involving 290 patients using aspirin for secondary prevention of cardiovascular disease.

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Participants were randomly assigned to 100 mg aspirin on awakening or at bedtime during two three-month periods. Blood pressure and platelet activity were measured at the end of each period. One hundred seventy patients had complete measurements available at both time points.

In the bedtime aspirin group, there was a reduction in aspirin platelet activity (22 aspirin reaction units), the researchers found. No reduction in blood pressure was noted in either group.

“This study showed that intake of aspirin at bedtime compared with intake on awakening does not reduce blood pressure of patients with CVD. However, bedtime aspirin reduced morning platelet reactivity, which might reduce excess cardiovascular events during high risk morning hours,” the researchers concluded.


  1. Bonten T et al. Abstract #CS.03. “Does Aspirin Intake at Bedtime Decrease Blood Pressure and Morning Peak of Platelet Reactivity?: A Randomized Cross-over Trial.” Presented at: American Heart Association 2013 Scientific Sessions. Nov. 16-20, 2013. Dallas.