Association between napping and nighttime sleep with the risk of recurrent events in patients with cardiovascular disease: pilot study of the MEDLIFE project

Introduction Previous studies have identified a possible relationship between sleep patterns and the risk of cardiovascular disease (CVD). To our knowledge, the relationship between time spent napping, hours of sleep, and the risk of recurrent events has not been previously analysed in patients with CVD. Purpose The aim of this study was to evaluate the relationship between napping and nighttime sleep and the incidence of major adverse cardiovascular events (MACE) in a cohort of patients with established CVD. Methods The pilot study of the MEDLIFE project included a prospective cohort of patients hospitalised for ischaemic heart disease, atrial fibrillation, and heart failure. At baseline, we assessed lifestyle habits using a validated questionnaire and classified participants according to their average nap and nighttime sleep duration. MACEs were defined as the incidence of a combined outcome comprising acute myocardial infarction or new revascularization, diagnosis or decompensation of heart failure, nonfatal stroke, and cardiovascular mortality. Multivariable Cox regression models were used. Results We included 159 participants, who were followed-up for a median of 17 months, and we identified 56 MACE. Among the participants, 17% reported no napping, 35% napped for a maximum of 30 minutes, and 48% napped for more than 30 minutes. Of the participants, 55% reported sleeping between 6-8 hours/day, 21% sleeping less than 6 hours/day, and 24% sleeping more than 8 hours/day. Participants who slept >8 hours/day had an increased risk of MACE (adjusted HR = 2.04; 95% CI: 1.01-4.11), compared to those who slept between 6-8 hours. In the same model, participants who napped >30 minutes/day were observed to have an increased risk of MACE, compared to those who did not nap (adjusted HR = 2.91; 95% CI: 1.05-8.06). Conclusions Sleeping for more than 8 hours at night and a prolonged nap of more than 30 minutes were associated with an increased risk of MACE in patients with established CVD. These findings suggest the importance of promoting adequate rest as a secondary prevention strategy in patients with CVD.