Sleep structure in patients with periodic limb movements and obstructive sleep apnea syndrome

Periodic limb movements (PLM) and obstructive sleep apnea syndrome (OSAS) are two frequent sleep disorders which often occur in the same patient. The goal of this study was to know the influence of the presence of PLM in the sleep architecture in patients with and without OSAS. Two hundred twenty consecutive patients (69 women and 151 men) participated in this transversal study. They were patients with clinical suspicion of dysomnia, including snoring, OSAS, and PLM. All of them underwent a full polysomnography and were interviewed using questionnaires about the sleep quality. The sleep parameters (percentage of sleep stages, rapid eye movement latency, sleep efficiency, awakenings, PLM presence, apnea-hypopnea index) were calculated and compared between groups. Descriptive statistics and nonparametric distribution techniques were used for the analysis. Patients with PLM when compared with patients with OSAS had lower sleep efficiency and less rapid eye movement percentage. The presence of PLM in patients with sleep apnea was less relevant being responsible only for an increase in the rapid eye movement latency and a decrease in the duration of the three to four sleep stages. However, the presence of OSAS was related to a better sleep efficiency (patients with PLM plus OSAS had a better sleep efficiency than patients with only PLM). PLM alters the structure of sleep. In patients with sleep apnea, the presence of PLM is less relevant.