The Impact of Exercise on Sleep Quality in Individuals with Multiple Sclerosis

Background: Sleep disturbances are commonly experienced by individuals with multiple sclerosis (MS) with over 50% reporting sleep issues.  Exercise has been shown to have a moderate improvement on sleep quality in adults with sleep problems.

Objectives: The purpose of this study was to examine the effect of exercise on sleep quality in individuals with MS.

Methods: Twenty-two individuals with relapsing-remitting or secondary-progressive MS (49.8 ±12.7 years of age; 19 females, 3 males) who were ≥ 70% compliant with the exercise program were included in data analysis. During baseline assessment, participants completed the Pittsburgh Sleep Quality Index (PSQI) to assess sleep quality and underwent a submaximal exercise test to predict cardiorespiratory fitness (measured as predicted peak VO₂). Participants were randomized into either a supervised moderate-intensity AE group or a home exercise program (HEP) group which consisted of stretching and walking at a low intensity. Following 12-weeks of exercise, participants underwent reassessment. Mixed model ANOVAs were performed (Time as within-subject measure, Group as between-subject measure). Effect size for the F-statistic (partial eta; ƞ_p²) is reported and interpreted as small= .01, moderate=.06, and large=.14. Percent-change and Cohen’s d were calculated for each group. Spearman correlation assessed the relationship between change in predicted peak VO2 and change in PSQI.

Results: There was a near significant group X time interaction for predicted peak VO₂ , F(1,20)=3.79, p=0.066, ƞ_p²=.159. The AE group demonstrated a 13.3% increase (ES=.36) and the HEP group demonstrated a 3.2% reduction (ES=.08) in predicted peak VO₂. The group X time interaction was not significant for sleep quality (p=.447). However, both groups demonstrated improvement on the PSQI (12% for AE, ES=0.51; 22% for HEP, ES=0.82). Change in predicted peak VO2 was not associated with change in PSQI (r_s = -.017; p= .942).

Conclusions: The results suggest that moderate-intensity AE improves cardiorespiratory fitness in people with MS. While both groups experienced moderate to large effects on sleep quality, the mechanism for improvement in sleep quality remains to be determined as the improvement was not related to change in cardiorespiratory fitness.  Although studies are needed to determine the mechanism, exercise may be a method to address reduced sleep quality in certain people with MS.