Insomnia is a frequent reason for medical and psychiatric consultation in prisons. Medical decision-making in correctional health care should be based on the same principles as outside correctional institutions. In places of detention, principles should be balanced according to the same criteria as outside correctional institutions, while taking into account the unique harm-benefit ratios related to the specific context. The aim of this paper was to examine the existing attitudes and ethical issues related to decision-making about insomnia evaluation and treatment in places of detention. An analysis of the ethical issues and an evidence-based review of the consequences of different attitudes and treatments with regard to prison medicine were carried out. Insomnia is a public health problem and requires adequate evaluation and treatment to avoid more serious health consequences both within and outside correctional institutions. Insomnia treatment in places of detention is an ethical dilemma, but there is no evidence-based reason to avoid benzodiazepines in prison completely and to use only neuroleptics and antidepressants, which might represent more dangerous and less efficient treatment. In prison medicine, should we even treat insomnia? Widely accepted ethical strategies of decision-making indicate that we should. Institutional guidelines on insomnia should be based on ethically sound decision-making that takes into account the available evidence.