To get the best out of your daily blood pressure medication, take it just before you go to bed, say researchers.
It's a simple tip that could save lives, they say in the European Heart Journal.
The pills offer more protection against heart attacks and strokes when taken at bedtime rather than in the morning, a large new study suggests.
Experts believe our body's biological 'clock' or natural 24-hour rhythm alters our response to the medication.
Synchronise pills to your body clock
There is mounting evidence that many different drugs, including heart pills, might work better when taken at specific times of the day.
This latest trial is the largest so far to look at the phenomenon with high blood pressure pills, and included more than 19,000 people on these medications.
In the Spanish study:
- The patients were put into two groups at random - one group took the pills in the morning and the other group took them at bedtime
- Researchers monitored what happened to the patients over the next five or more years
- Patients who took their medication in the evening had nearly half the risk of dying from - or having - a heart attack, stroke or heart failure
Blood pressure should naturally dip at night, as we rest and sleep.
If it doesn't, and remains consistently high, that puts you at increased risk of heart attacks and strokes, experts say.
The research suggests taking medication in the evening helps keep night-time blood pressure in check, in patients diagnosed with high blood pressure (which doctors call hypertension).
Patients in the study who took their medication at bedtime had significantly lower average blood pressure both at night and during the day, and their blood pressure dipped more at night, when compared with patients taking their medication each morning.
Lead researcher Prof Ramon Hermida, from the University of Vigo, said doctors might want to consider recommending it to patients: "It's totally cost-free. It might save a lot of lives.
"Current guidelines on the treatment of hypertension do not 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.
"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."
He said more studies in different populations were needed to check that the findings will apply to all patients on different brands of blood pressure tablets.
Vanessa Smith, from the British Heart Foundation, said: "Although this study supports previous findings in this area, further research amongst other ethnic groups and people who work shift patterns would be needed, to truly prove if taking blood pressure medication at night is more beneficial for cardiovascular health.
"If you're currently taking blood pressure medication, it's important to check with your GP or pharmacist before changing the time you take it. There may be specific reasons why your doctor has prescribed medication in the morning or night."
Lifestyle factors also make a difference to blood pressure, so avoid:
- Drinking too much alcohol
- Being overweight
- Not doing enough exercise
- Eating too much salt