• cataplexy;
  • multiple sleep latency test;
  • polysomnography;
  • questionnaire study;
  • sleep co-morbidity;
  • sleepiness;
  • Wilson's disease

Background:  Wilson’s disease (WD) is an autosomal recessive inherited disease with copper accumulation; neurodegeneration is associated with dopaminergic deficit. The aim of the study is to verify sleep co-morbidity by questionnaire and objective sleep examinations (polysomnography, multiple sleep latency test).

Methods:  Fifty-five patients with WD (22 hepatic, 28 neurological, five asymptomatic form) and 55 age- and sex-matched control subjects completed a questionnaire concerning their sleep habits, sleep co-morbidity, Epworth sleepiness scale (ESS), and answered screening questions for rapid eye movement (REM) behaviour disorder (RBD-SQ). Twenty-four patients with WD and control subjects underwent polysomnographic examination.

Results:  Unlike the controls, patients with WD were more prone to daytime napping accompanied by tiredness and excessive daytime sleepiness, cataplexy-like episodes and poor nocturnal sleep. Their mean ESS as well as RBD-SQ was higher than that of the controls. Total sleep time was lower, accompanied by decreased sleep efficiency and increased wakefulness. Patients with WD had lower latency of stage 1 and stage 2 of non-rapid eye movement (NREM) sleep and less amount of NREM sleep stage 2. One-third of the patients with WD were found to have short or borderline multiple sleep latency test (MSLT) values independent of nocturnal pathology (sleep apnoea, periodic leg movements and/or restless leg syndrome).

Conclusions:  Patients with WD often suffer from sleep disturbances (regardless of the clinical form). The spectrum of sleep/wake symptoms raises the suspicion that altered REM sleep function may also be involved.