Drinking a few cups of coffee each day can improve your heart and overall health – but does the timing of your caffeine consumption affect its benefits?
It certainly can, according to research published today in European Heart Journal.
A new study – the first to examine the timing of coffee consumption on heart health – found that people who drink coffee in the morning have a lower risk of dying from cardiovascular disease compared to those who drink coffee throughout the day and don’t drink coffee.
Morning coffee drinkers also had a lower overall risk of death compared to others in the study.
“Our findings show that it’s not just whether you drink coffee or how much, it’s the time of day when you drink it that matters,” senior author of the study Lu Kee, MD, PhDin press release.
“We don’t usually give advice on timing in our dietary guidelines,” Key added, “but maybe we should think about it in the future.”
Previous research has shown the health benefits of coffee, including reducing the risk of type 2 diabetes and not increasing the risk of cardiovascular disease. However, the timing of coffee consumption has yet to be studied.
“Given the effects caffeine has on our bodies, we wanted to see if the time of day you drink coffee affects heart health,” Key said in a press release.
For this study, researchers analyzed data from 40,725 adults who participated in the US National Health and Nutrition Examination Survey (NHANES) between 1999 and 2018. Participants were asked about all the food and beverages they consumed in a day—including coffee—and directed to include how much and when.
Another cohort of 1,463 adults who participated in the Women’s and Men’s Lifestyle Validation Study was used to externally validate coffee drinking patterns in the NHANES data. The researchers then compared the data with death data over a period of about 10 years.
Of all participants, 36% primarily drank coffee before noon, 16% drank coffee throughout the day, and 48% did not drink coffee.
The results showed that, compared to non-coffee drinkers, morning coffee drinkers were 16% less likely to die from any cause and 31% less likely to die from cardiovascular disease. There was no reduction in risk for all-day coffee drinkers compared to non-coffee drinkers, suggesting that drinking coffee during the day was no better than no coffee at all.
Morning coffee drinkers appeared to benefit from a reduced risk regardless of how much they drank, but the association was somewhat weaker for light coffee drinkers who drank one cup or less per day.
While the study controlled for factors such as diabetes, hypertension, high cholesterol, smoking, physical activity and more, the research still had limitations.
As an observational study, Kee said the research cannot provide evidence of causation, and more studies in other populations are needed to confirm the findings.
The study didn’t offer any explanations for why drinking coffee in the morning might be a healthier option for the heart, but one possibility has to do with how coffee affects circadian rhythms, Key said.
The circadian rhythm is the body’s internal clock that regulates when you sleep and when you wake up, as well as several other key functions. Qi said drinking coffee later in the day can disrupt hormone levels like melatonin, affecting the body’s circadian rhythm and disrupting sleep.
Thomas F. Luscher, MD, FRCPconsultant cardiologist and director of research, education and development at the Royal Brompton and Harefield Hospitals in the UK, explained the circadian rhythm link in an editorial accompanying the study.
“Many all-day (coffee) drinkers suffer from sleep disorders,” he wrote. “In this context, it is interesting that coffee appears to suppress melatonin, an important sleep-inducing mediator in the brain.”
Sleep is essential for general well-being and is especially important for heart health as it relates to blood pressure. Your blood pressure drops while you sleep, so sleep problems can cause your blood pressure to stay higher for longer periods of time, increasing your risk of heart disease and stroke.
The study authors also wrote that coffee’s anti-inflammatory benefits may be strongest if coffee is consumed in the morning, as some markers of inflammation in the blood peak in the morning.
The study shows that drinking coffee is good for your health, and if you’re going to drink it, you should do it in the morning, Kee said.
Lischer agreed with Kiev’s recommendation. “We must accept the now substantial evidence that drinking coffee, especially in the morning, is likely to be healthy,” he wrote in an editorial. “So drink your coffee, but do it in the morning!”
If you still need an afternoon date, try drinking coffee at least nine hours before you go to bed—a 2023 study found that drinking coffee within 8.8 hours of going to bed can disrupt sleep.