Those that took their medications at bedtime were found to have a 45% decreased risk of dying from or suffering a heart attack, stroke, myocardial infarction, heart failure, or requiring procedures to unblock narrowed arteries compared to those who took their meds when they woke up. Analysis was adjusted to account for factors that may affect results such as gender, age, smoking and cholesterol levels, kidney disease, and type 2 diabetes. The risk of death from heart or blood vessel problems was reduced by 66%, risk of stroke was reduced by 49%, the risk of myocardial infarction was reduced by 44%, the risk of heart failure was reduced by 42%, and the risk of coronary revascularisation was reduced by 40% when looking at individual outcomes.
Professor Ramón C. Hermida said: “Current guidelines on the treatment of hypertension do not mention or recommend any preferred treatment time. Morning ingestion has been the most common recommendation by physicians based on the misleading goal of reducing morning blood pressure levels. However, the Hygia Project has reported previously that average systolic blood pressure when a person is asleep is the most significant and independent indication of cardiovascular disease risk, regardless of blood pressure measurements taken while awake or when visiting a doctor. Furthermore, there are no studies showing that treating hypertension in the morning improves the reduction in the risk of cardiovascular disease. The results of this study show that patients who routinely take their anti-hypertensive medication at bedtime, as opposed to when they wake up, have better-controlled blood pressure and, most importantly, a significantly decreased risk of death or illness from heart and blood vessel problems.”
A total of 292 doctors are involved in The Hygia Project which is comprised of a network of 40 primary care centres within the Galician Social Security Health Services in northern Spain. 10,614 men and 8,470 women aged 18+ who were diagnosed with hypertension were recruited for the trial, and had to adhere to a daily routine of morning activity and night time sleeping, meaning the findings may not apply to those who work night shifts.
Blood pressure was taken when participants joined the study and again at each subsequent clinic visit; ambulatory blood pressure monitoring over a 24 hour period took place after each clinic visit and at least once a year to provide accurate information on average blood pressure over the period including dips while the participants were sleeping. During an average followup of six years 1752 participants died from heart or blood vessel problems, or experienced stroke, heart failure, myocardial infarction, or coronary revascularisation. Based on data from ambulatory blood pressure monitoring those that took their medication at bedtime had significantly lower average blood pressure throughout the entire day/night, and blood pressure dipped more at night compared to those who took meds when they woke up. Progressive decrease in night time systolic blood pressure during the follow up period was the most significant predictor of reduced risk of CVD.
Professor Hermida concluded: “The findings from the Hygia Chronotherapy Trial and those previously reported from the Hygia Project indicate 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. Accordingly, round-the-clock ambulatory blood pressure monitoring should be the recommended way to diagnose true arterial hypertension and to assess the risk of cardiovascular disease. In addition, decreasing the average systolic blood pressure while asleep and increasing the sleep-time relative decline in blood pressure towards more normal dipper blood pressure patterns are both significantly protective, thus constituting a joint novel therapeutic target for reducing cardiovascular risk.”
Limitations include requiring validation in other ethnic groups; the question of whether the same results would be seen in shift workers also requires investigation; and patients were not assigned to specific hypertension medication classes or specific lists of medications within each class as treatment was chosen by participant’s doctors.
