Objective To evaluate the frequency, severity and determinants of sleep disturbances in patients with amyotrophic lateral sclerosis (ALS).

Methods Information about night-time complaints was collected using a standardised questionnaire, the Pittsburgh Sleep Quality Index (PSQI), and the Epworth Sleepiness Scale (ESS) in a group of 100 patients with ALS and in 100 control subjects matched for age and sex. Functional disability was assessed using the ALS Functional Rating Scale-Revised (ALSFRS-R). Sleep was studied by overnight polysomnography in 12 patients.

Results Fifty-nine patients with ALS and 36 controls reported sleep disturbances. The mean global PSQI score of patients with ALS was significantly higher than the control participants (6.82±4.0 vs 4.86±3.2), and three of the seven components of PSQI in patients with ALS were significantly different from controls: ‘sleep latency,’ ‘habitual sleep efficiency’ and ‘sleep disturbances.’ The most commonly reported night-time complaints by patients with ALS were nocturia (54%), sleep fragmentation (48%) and nocturnal cramps (45%). Poor sleep was associated with decreased ALSFRS-R score, highest depression and ESS score. After a multivariate analysis, patients' disability and daytime somnolence remained significantly associated with sleep quality. Polysomnographic studies showed decreased sleep efficiency and fragmented sleep architecture.

Conclusion This study demonstrated that patients with ALS have a significant poor quality of sleep, and this correlated with the severity of ALS and daytime somnolence. Increased awareness for sleep–wake problems in patients with ALS is important, as effective intervention could lead to a better management of these patients.