Sepsis is a condition where the immune response to a severe infection becomes dysregulated and life-threatening. Sepsis is associated with high mortality and great personal suffering. Lifestye factors such as physical activity, smoking and alcohol consumption affects cardiopulmonary capacity, which indicates that they may affect the risk of surviving sepsis. However, it is not known if there exists an association between these modifiable risk factors and sepsis. Participants in the large population-based cohorts Swedish Mammography Cohort and Cohort of Swedish Men have answered life style questionnaires and been followed through the In-Patient and Death Registers. For this project, the cohorts will be further connected to the Swedish intensive care register in order to acquire intensive care unit admissions, disease severity at admission and treatment during intensive care. We aim to investigate the association between lifestyle and the risk of contracting and dying in sepsis, as well as health and disease in sepsis survivors, in this uniquely large and detailed material using advanced epidemiological methods capable of controlling confounding factors, such as multivariable regression informed by directed acyclic graph methodolog. This has previously not been possible as previous studies have been too small and not had sufficiently detailed data. This study will provide important new knowledge how life style affects the risk of sepsis. Further knowledge may inform public health recommendations aimed at preventing sepsis and help health care professionals identify high risk patients