More than one billion people have high blood pressure worldwide, and it has ­become the ­leading global cause of early death.

But there has been a big unresolved question about the timing of taking blood pressure medication. There have been claims that people should take their medicine at night.

Night-time blood pressure was thought to be a better predictor of cardiovascular outcomes than daytime readings, and there was a suggestion that evening dosing of medication reduced night-time blood pressure to a greater extent.

However, the TIME trial – the largest study to date on the issue – found that there was no meaningful difference in rates of hospitalisation for heart attack, stroke and vascular death between people who took their medication in the morning and those who took it in the evening.

Professor Bryan Williams of ­University College London is on the steering committee for the TIME trial, which involved more than 21,000 patients over five years, and has confirmed that taking blood pressure tablets in the evening is no better than in the morning to protect against the diseases and risks of hypertension.

The results of the trial should ­reassure patients they can take their medication when it suits them.

Prof Williams added: “This is a study of huge practical importance.

“There has been much controversy and uncertainty over a simple ­question affecting hundreds of millions of people worldwide; notably, is taking blood pressure tablets in the evening better in terms of protecting patients with high blood pressure from heart disease and stroke?

“The answer is no. Patients should take their tablets when they are most likely to remember to take them.”

Principal investigator Professor Thomas MacDonald of the University of Dundee said: “The trial clearly found that heart attack, stroke and vascular death occurred to a similar degree regardless of the time of administration. People with high blood pressure should take their regular antihypertensive medications at a time of day that is convenient for them and minimises any undesirable effects.”

Professor Sir Nilesh Samani, medical director at the British Heart Foundation, which funded the study, added: “These results show that the time of the day people take their blood ­pressure tablets does not matter and they should take them at the time that suits them best”.

The study team compared rates of hospitalisations due to non-fatal heart attack or non-fatal stroke, and vascular death, between one group given their medication in the morning, and the other in the evening.

There was no significant difference (3.4% vs 3.7%) to report.