In a French prison, most inmates reported not being satisfied with their sleep. Life habits between good and bad sleepers were not significantly different except for television and smoking. The most frequently reported symptom of insomnia was several awakenings at night, and the most frequently cited etiologies were rumination of thoughts and noise. Most patients reported that their sleeping problems began or worsened after incarceration. A quarter of the inmates were following a hypnotic treatment, and most of these treatments began in prison. Only 42% of patients were satisfied with its effectiveness. These observations enabled us to make recommendations for healthy sleep patterns such as respecting normal night-and-day cycles, encouraging to stop smoking, and promoting appropriate use of hypnotic treatments.