Evaluation of Sleep Quality and Fatigue in Patients with Usher Syndrome Type 2a

To study the prevalence, level, and nature of sleep problems and fatigue experienced by Usher syndrome type 2a (USH2a) patients.

Cross-sectional study.

Fifty-six genetically confirmed Dutch patients with syndromic USH2a and 120 healthy controls.

Sleep quality, prevalence, and type of sleep disorders, chronotype, fatigue, and daytime sleepiness were assessed using 5 questionnaires: (1) Pittsburgh Sleep Quality Index, (2) Holland Sleep Disorders Questionnaire, (3) Morningness-Eveningness Questionnaire, (4) Checklist Individual Strength, and (5) Epworth Sleepiness Scale. For a subset of patients, recent data on visual function were used to study the potential correlation between the outcomes of the questionnaires and disease progression.

Results of all questionnaires were compared between USH2a and control cohorts, and the scores of the patients were compared with disease progression defined by age, visual field size, and visual acuity.

Compared with the control population, patients with USH2a experienced a poorer quality of sleep, a higher incidence of sleep disorders, and higher levels of fatigue and daytime sleepiness. Intriguingly, the sleep disturbances and high levels of fatigue were not correlated with the level of visual impairment. These results are in accordance with the patients' experiences that their sleep problems already existed before the onset of vision loss.

This study demonstrates a high prevalence of fatigue and poor sleep quality experienced by patients with USH2a. Recognition of sleep problems as a comorbidity of Usher syndrome would be a first step toward improved patient care. The absence of a relationship between the level of visual impairment and the severity of reported sleep problems is suggestive of an extraretinal origin of the sleep disturbances.

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