Military deployments and mental health problems (MHPs) have often been studied, but only infrequently in the deployed environment, where MHP-related impairments would be particularly consequential. Fewer still have looked at deployed sailors, so Whybrow et al's1 cross-sectional survey of MHPs among Royal Navy personnel deployed at sea is a welcome addition to the literature. They found that 41.2% had common mental disorder symptoms (ie, mood, anxiety or neurotic spectrum disorders), 7.8% probable post-traumatic stress disorder (PTSD), and 17.4% potentially harmful alcohol use. These prevalence rates are strikingly higher than those in deployed UK land-based forces using comparable methods; common mental disorder rates varied from 16.0% to 20.8% and probable PTSD from 1.9% to 3.4%.2 3 An earlier study of deployed Royal Navy personnel documented similarly elevated rates, suggesting that the present findings are not a chance occurrence.4

Past research has focused on operational trauma as the primary driver of poor mental health in military personnel, both on deployment and afterwards. The low trauma exposure in the present study suggests other attributions for the high levels of MHPs, such as premilitary characteristics and experiences, …