This research was attempted to assess causal relationships of multiple lifestyle factors with heart failure risk by using Mendelian randomization. Researchers collected summary statistics data for single nucleotide polymorphisms correlated with the following 5 lifestyle factors at genome-wide significance in genome-wide association studies of European-descent individuals: smoking, alcohol consumption, coffee consumption, physical activity, and sleep duration. They included corresponding data for heart failure from a genome-wide association study comprising 47,309 cases and 930,014 controls of European ancestry. The inverse-variance weighted method was applied for the primary analyses. Whereas longer sleep duration decreases the risk of heart failure, this Mendelian randomization study exhibited that smoking initiation increases heart failure risk. In heart failure prevention guidelines, sleep duration should be regarded as a novel risk factor. For heart failure, the potential causal role of alcohol and coffee consumption and physical activity needs future evaluation in future larger Mendelian randomization analyses.