Aims: To explore the possibility that stable MMP patients have sleep-disordered breathing (SDB) and abnormal sleep architecture defined by nocturnal sleep stages and sleep efficiency.
Setting: Regional Methadone Service and sleep disorders laboratory in a university affiliated hospital. Participants and measurements. Ten stable MMP patients and nine normal subjects were assessed clinically and with overnight polysomnography.
Findings: There were no differences in age, sex and body mass index between the groups. The methadone dose ranged between 50 and 120 mg/day. Six patients had central apnoea index (CAI) greater than 5, four had a CAI greater than 10 and three of these exhibited periodic breathing. No normal subject had central sleep apnoea. The patients had lower sleep efficiency (p < 0.05), less slow wave sleep (p < 0.01), less rapid eye movement sleep (p < 0.05) and more Stage 2 sleep (p < 0.05) than controls.
Conclusions: Stable MMP patients have more sleep architecture abnormalities than controls and a higher prevalence of central sleep apnoea. Further studies are needed to confirm these findings, to delineate the mechanisms for the abnormalities and to assess whether the SDB is related to sudden death in stable MMP patients. We recommend that MMP patients have awake and sleep respiration assessed to identify those potentially at risk.