The role of lifestyle on mental health in the ambulance worker population is unclear. The aim of this paper is to explore the role and impact of lifestyle on the mental health of ambulance workers within the United Kingdom (UK). Participants (N = 160) were recruited from 4 NHS ambulance trusts in England. Data were collected on lifestyle factors (sleep, physical activity and alcohol use) and mental health outcomes (trauma, anxiety, depression and stress); these were assessed by use of various questionnaires including validated measures. Sleep was shown to be the single biggest unique and significant predictor to all mental health outcomes. Suggestions for future research and intervention are considered.