Sleeping for seven hours a day may reduce the age of your heart, and lower the risk of cardiovascular disease, a study has found. Preliminary results from the study published in the journal Sleep show that excess heart age (EHA) appeared to be lowest among adults who reported sleeping seven hours per 24-hour period. Sleeping times less than or greater than seven hours were associated with increased excess heart age, and the highest elevations in EHA were noted in short sleepers, researchers said. Sleep duration coupled with EHA may prove helpful for communicating the cardiovascular risks and benefits associated with sleep duration. "These results are important because they demonstrate a quantitative method for the inclusion of sleep duration in the establishment and communication of cardiovascular risk for individuals," said Julia Durmer from Emory University in the US. "This could have utility in the clinical care of patients with cardiovascular risk, and for public health researchers interested in adding a sleep metric to future studies," said Durmer. The study involved 12,775 adults ranging in age from 30-74 years who responded to the 2007-2014 US National Health and Nutrition Examination Survey (NHANES). Self-reported sleep duration was classified into five categories (5 or less, 6, 7, 8, and 9 or more hours of sleep per night). They used the sex-specific Framingham heart age algorithm to calculate each individual's heart age and used multi-variable linear or logistic regression to examine the association between sleep duration and EHA or risk of EHA 10 years or more.