Fatigue, sleep, and nocturnal complaints in patients with amyotrophic lateral sclerosis

Background and purpose: Fatigue is a common symptom in amyotrophic lateral sclerosis (ALS). Although sleep disturbances are a candidate factor that may interfere with fatigue in patients with ALS, the role of sleep-related abnormalities in determining fatigue in ALS is unknown. Objective: To evaluate the frequency and determinants of fatigue in a group of 91 consecutive patients with ALS, with special attention to the relationship between fatigue and sleep problems. Methods: Measures included the Fatigue Severity Scale (FSS), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), ALS Functional Rating Scale-Revised (ALSFRS-R), and Beck Depression Inventory (BDI). Results: The mean FSS score was 4.35 +/- 1.1, and 48 patients with ALS (52.75%) reported clinical significant fatigue. FSS score correlated with ALSFRS-R score, forced vital capacity, ESS, BDI, and global PSQI score. Patients with fatigue were significantly more disabled and more frequently reported difficulties staying asleep and nocturnal complaints, such as nocturia and disturbing muscle cramps. After multivariate analysis, patients' disability and nocturnal complaints were significantly associated with fatigue. Conclusion: In this study, we demonstrated that fatigue, a troublesome and disabling symptom in ALS, is associated with physical impairment and night-time complaints (such as nocturia and muscle cramps), suggesting that treating sleep problems might be useful in alleviating fatigue in these patients.