The precise impact on prisoners of increased prison populations and their overcrowding, alongside other factors, is unclear. Cell-sharing can be a protective factor and overcrowding itself does not explain why there are self-inflicted deaths in prisons. Most significantly, a high proportion of prisoners arrive in prison with risk factors that we know increase the risk of them harming themselves, such as substance withdrawal, uncertainty and anxiety about their own cases, the impact of and adjustment to imprisonment, family concerns, a history of previous abuse or self-harm, and mental health issues.
However, managing very high numbers of prisoners can hinder efforts to reduce prisoner suicide rates. For example, by causing an increase in transfers between prisons, some prisoners being located further from home and family support, a possible reduction in the time staff can spend with individual prisoners on care and risk assessment, and an increase in the length of time prisoners are locked in their cells, rather than engaged in regime activities, association and other purposeful activity.