ANTI-hypertensive medication prescribed to patients with high blood pressure does not currently have any recommended treatment time. However, researchers have now shown that patients who take their pills at bedtime have a 45% reduction in risk of death by a host of cardiovascular disorders such as heart attacks, stroke, and heart failure. The trail, named the Hygia Chronotherapy Trial, was led by Professor Ramón Hermida of the University of Vigo, Vigo, Spain. It is considered unique in that it was a longitudinal study spanning over 6 years and blood pressure was monitored at least once a year for 48 hours, rather than the usual 24 hours.
The study collected data from 19,084 high blood pressure patients taking anti-hypertensive medication either in the morning or evening. The participants all had to follow a set daytime activity and night-time sleep type routine and were monitored by 292 doctors from 40 primary healthcare centres within the Galician Social Security Health Service in northern Spain. The purpose of the 48-hour monitoring allowed data to be recorded on the extent of the blood pressure decrease whilst patients slept.
The researchers considered external factors that may also influence patient blood pressure levels, such as smoking and cholesterol levels, as well as age, sex and Type 2 diabetes mellitus diagnosis. Taking all of this into account, they found that those taking their pills at bedtime had a reduced risk of death by heart or blood vessel problems by 66%, stroke by 49%, myocardial infarction by 44%, heart failure by 42%, and coronary revascularisation by 40%. The authors admitted they are yet to find out if these findings apply to people who work night shifts, and that the results require validation in other ethnic groups besides Caucasian.
As there appears to be such a strong link between lowering average blood pressure at night and reduced risk of cardiovascular disease, it is Professor Hermida’s hope that this approach of long-term monitoring will be adopted as a new way to diagnose arterial hypertension. He notes that “average blood pressure levels while asleep and night-time blood pressure dipping, but not day-time blood pressure or blood pressure measured in the clinic, are jointly the most significant blood pressure-derived markers of cardiovascular risk.” The Hygia project is still ongoing and has now steered its focus towards investigating the optimal sleeping blood pressure levels to reduce cardiovascular risk in what is known as the Treatment of Hypertension During Sleep (THADEUS) Trail.