Periodic limb movements during sleep and progression of sleep apnea: a longitudinal analysis from the Wisconsin sleep cohort

Purpose: To explore whether Periodic Limb Movements during Sleep (PLMS) are an intrinsic feature of sleep physiology or influenced by the progression of sleep apnea using longitudinal data. Methods: This study analyzed data from 39 participants in the Wisconsin Sleep Cohort who transitioned from no or mild (Apnea-Hypopnea Index - AHI < 10) to moderate-to-severe sleep apnea (AHI > 15). Polysomnographic recordings measured PLMS and related leg movement indices, including respiratory-related limb movements (RRLM), at baseline and follow-up. Results: AHI increased significantly between baseline and follow-up, while the PLMS index remained stable. Predictors of follow-up PLMS index were limited to baseline PLMS index, with no significant effects from AHI or other confounding factors. Increased indices of short-interval and isolated leg movements were observed but did not impact the PLMS index. Conclusion: PLMS appear to be a relatively consistent feature of individual sleep patterns, independent of respiratory disturbances. This novel approach, examining pre-apnea recordings, provides unique insights into the interplay of limb movements and respiratory events in sleep-disordered breathing.