Insomnia in prison is common; however, research is limited regarding the management strategies that prison establishments employ. To address this knowledge gap, we conducted a survey to identify how insomnia is detected, diagnosed and treated in adult prisons in England and Wales. Telephone interviews with a purposive sample of health-care managers were then conducted. The survey was sent to all establishments holding adult prisoners, covering screening and assessment methods to detect insomnia; treatment options, both pharmacological and non-pharmacological; the importance of insomnia as a treatable condition; and staff training available. Eighty-four (73%) prisons completed the survey. Few had a stepped approach to insomnia management, as recommended by National Institute for Health and Care Excellence (NICE) guidelines. The most common treatments available were sleep hygiene education and medication, offered by 94 and 88% of respondents, respectively. Analysis of telephone interviews revealed four main themes: insomnia as a normal occurrence in prison; the problem of medication in prison; the negative impact of the prison environment; and effective management of insomnia in prison. The current findings suggest that logistical, ethical and security barriers and a lack of staff knowledge and training impact negatively on the management of insomnia in prison.