Findings of a cross-sectional study of patients with multiple sclerosis (MS) revealed positive correlations between both sleep quality and sleep latency and motor skill acquisition.

Researchers also found plasma serotonin levels correlated significantly with the time it took individuals to complete a motor task: the higher the serotonin level, the quicker the task was completed.

In this pilot study, Al-Sharman et al. at Jordan University of Science and Technology studied the effects of sleep quality and sleep-related biomarkers on motor skill acquisition in 40 individuals with MS, compared with 40 individuals in a control group. They used a novel virtual reality game involving sit-to-stand movements to calculate motor skill acquisition. An enzyme-linked immunosorbent assay (ELISA) calculated plasma serotonin level biomarkers.

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Sleep quality was assessed subjectively using the Pittsburgh Sleep Quality Index (PSQI) and objectively using Actisleep technology. The Actisleep device measured the time between bedtime and sleep onset (sleep latency) and the number of sleep minutes divided by total minutes in bed (sleep efficiency). Sleep disturbances were indicated by sleep efficiency of less than 85% and sleep latency of greater than 30 minutes.

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Both sleep efficiency and plasma serotonin levels were negatively correlated with motor skill acquisition. The inverse relationship between higher serotonin levels and lower scores indicating better sleep quality may explain enhanced motor skill acquisition, study authors said. 

According to this study, sleep disturbances including insomnia, restless leg syndrome (RLS), sleep apnea, and rapid eye movement sleep behavior disorder (RBD) are common in approximately 70% of patients with MS. The authors noted a paucity of research assessing the effect of sleep and sleep-related biomarkers on motor skill acquisition in this patient population. According to the researchers, many studies indicate that physiological sleep patterns affect both acquisition and consolidation phases of motor skill learning. Hence, sleep quality plays a critical role in motor memory development.

Physical therapists develop activity-focused neurorehabilitation interventions for patients with MS to reinforce practice and repetition of motor skills. The authors of this study attest, “physical therapists are encouraged to be aware of sleep quality and sleep assessment,” and the impact sleep quality has on motor skill learning in patients with MS. Sleep continuity, or undisrupted sleep, is a critical factor in motor skill learning. 

The authors strongly suggest that sleep assessments should be performed as an integral part of MS patient evaluation, and sleep management strategies should be an included intervention to improve neurorehabilitation outcomes. Strategies to improve sleep quality include music therapy, resistance training, aerobic exercise, and cognitive behavioral therapy (CBT). 

One study limitation was the lack of diversity in MS disease severity since participants had mild levels of MS. Another limitation was that sleep assessment did not include sleep architecture, rendering determination of which sleep stages contributed to motor skill acquisition impossible. Lastly, data from the Actisleep devices were obtained from only 15 MS participants. This limited the interpretation and comparison of sleep latency and efficiency. 


Al-Sharman A, Al-khazaaleh HM, Khalil H, Aburub AS, El-Salem K. The relationship between sleep quality, sleep-related biomarkers and motor skill acquisition in people with multiple sclerosis: a pilot study. Phys Ther Rehabil J. Published online July 16, 2021. doi:10.1093/ptj/pzab175