Many patients are prescribed by their doctor a daily intake of aspirin to reduce the risk of cardiovascular disease or a relapse of stroke. Indeed, even at low doses, this analgesic (pain medication) thins the blood and prevents clots from forming. For many patients, taking aspirin is therefore one of the first things they do in the morning, to start the day in good shape. However, researchers at the University of Leiden in the Netherlands have just discovered that this daily intake of aspirin is more effective at bedtime than in the morning when waking up.
To study the link between chronobiology and aspirin, the team of Dr Tobias Bonten, from the University of Leiden, recruited 290 patients who were asked to take a low dose of aspirin every morning for three months, then every night for another three months. At the end of each quarter, all were tested to check their blood pressure and platelets. Platelets are the blood cells that allow clotting: aspirin prevents them from getting closer to each other and thus reduces their possibility of forming clots that could trigger a stroke or heart attack.
The schedule of the aspirin does not seem to have had any effect on blood pressure but, on the other hand, when the analgesic is taken in the evening, it prevents the platelets from aggregating in the early morning, when there is the most infarction.
