Maybe think twice before reaching for that afternoon coffee or after-dinner espresso.

A study from Tulane University found that those who limit coffee drinking to the morning have a lower risk of dying of heart disease and a lower overall mortality risk than those who drink coffee throughout the day.

The study, published in European Heart Journal, also found that morning coffee drinkers had better heart health and lower mortality rates than those who skipped the joe altogether.

“Research so far suggests that drinking coffee doesn’t raise the risk of cardiovascular disease, and it seems to lower the risk of some chronic diseases, such as diabetes,” said lead author Dr. Lu Qi, HCA Regents Distinguished Chair and professor in the Celia Scott Weatherhead School of Public Health and Tropical Medicine. “Given the effects that caffeine has on our bodies, we wanted to see if the time of day when you drink coffee has any impact on heart health.”

The study included 40,725 adults taking part in the U.S. National Health and Nutrition Examination Survey (NHANES) between 1999 and 2018. As part of this study, participants were surveyed about whether they drank coffee, how much and when. Researchers were able to link this information with records of deaths and cause of death over this period of time.

Around 36% of people in the study were morning coffee drinkers (they primarily drank coffee before midday), 16% drank coffee throughout the day (morning, afternoon and evening) and 48% were not coffee drinkers.

Compared with people who did not drink coffee, morning coffee drinkers were 16% less likely to die of any cause and 31% less likely to die of cardiovascular disease. There was no reduction in risk for all-day coffee drinkers compared to non-coffee drinkers.

Morning coffee drinkers benefitted from the lower risks whether they were moderate drinkers (two to three cups) or heavy drinkers (more than three cups). Light morning drinkers (one cup or less) benefitted from a smaller decrease in risk.

Qi said further studies are needed to explain why limiting coffee to the morning is linked to greater heart health benefits, but he surmised that “consuming coffee in the afternoon or evening may disrupt circadian rhythms and levels of hormones such as melatonin. This, in turn, leads to changes in cardiovascular risk factors such as inflammation and blood pressure.”

“This is the first study testing coffee drinking timing patterns and health outcomes,” Qi said. “Our findings indicate it’s not just whether you drink coffee or how much you drink, but the time of day when you drink coffee that’s important. We don’t typically give advice about timing in our dietary guidance, but perhaps we should be thinking about this in the future.”