Should you ever need heart surgery, it might be worth pressing for an afternoon appointment. New research in the Lancet finds patients who undergo morning heart surgery are twice as likely to suffer heart issues and other complications as patients who have surgery in the afternoon, per the BBC. It's not that doctors are drowsy in the morning and therefore prone to mistakes. Rather, researchers say the body's circadian rhythm regulates genes that are in top form and better able to handle stress in the afternoon, a fact that also explains why one's risk of heart attack is highest in the morning. To discover this, researchers conducted several studies, one monitoring 596 patients who underwent an aortic valve replacement, half in the morning, half in the afternoon.
After 17 months, they found 18% of morning patients had suffered a major adverse cardiac event, acute heart failure, cardiovascular death, or a heart attack during the operation, compared to 9% of afternoon patients. Morning patients also had twice the risk of other complications, per the study, which identified 287 genes linking the body clock to heart health, reports the Independent. A second study also found morning patients had significantly higher levels of troponin, a measure of heart damage, per the New York Times. This doesn't mean morning surgeries should be avoided, but "we should identify patients at high risk for complications—those with diabetes or other metabolic risks, for example—and operate on those in the afternoon," a study author tells the Times. (Read more heart surgery stories.)