The prison population in England and Wales is increasing, and research suggests that current rehabilitation methods are not adequate, contributing to the ‘revolving door’ phenomenon. Prisoners have high rates of complex mental health difficulties, and psychological therapies is one way to increase effective rehabilitation. Part one presents a scoping review of one particularly promising transdiagnostic psychological therapy: Acceptance and Commitment Therapy (ACT). This review found fifteen primary data studies that have investigated the use of ACT in prisons that were heterogenous in nature. They

suggested promising acceptability and feasibility of ACT in this environment, however for more robust conclusions, more data is required. Recommendations have been made to guide future research. 

Suicide is a substantial, and growing, health concern in the United Kingdom. Two potentially modifiable, transdiagnostic risk factors for suicide are poor sleep and mood instability. Part two presents a quantitative analysis using the most up-to-date Adult Psychiatric Morbidity Survey data, to explore the effect of poor sleep and mood instability on suicidal ideation, suicidal behaviours, and non-suicidal self-harm. The findings suggest an additive effect exists, such that individuals experiencing both poor sleep and mood instability incur greater risk of suicide and self-harm then individuals experiencing either difficulty alone. Future research and clinical implication are discussed.