Sleep Disturbances and Their Correlates in Essential Tremor and Essential Tremor Plus: A Questionnaire-Based Case-Control Study.

BACKGROUND: Essential tremor (ET) has been increasingly recognized to involve non-motor symptoms, including sleep disturbances. Essential Tremor Plus (ET-plus), is characterized by additional neurological "soft signs" and may display greater non-motor symptom burden. Despite emerging evidence from polysomnographic studies, large-scale subjective evaluations of sleep across the ET spectrum remain limited. OBJECTIVES: To assess the prevalence and severity of sleep disturbances in ET and ET-plus using validated sleep questionnaires, and to compare with healthy controls. METHODS: This study was conducted at NIMHANS, Bengaluru, and included 100 patients (60 ET and 40 ET-plus) and 100 healthy controls. Tremor severity was assessed using TETRAS and FTMRS, and sleep symptoms with ESS, PSQI, Mayo Sleep Questionnaire, RLS-Q, BQ, GAD-7 and PHQ-9. Non-parametric tests and effect size estimations were used for group comparisons. RESULTS: ET-plus patients were older and exhibited greater tremor severity than ET. Global PSQI scores differed significantly among ET and ET Plus vs controls (p < 0.001), with ET-plus reporting the poorest sleep quality. ET and ET-plus demonstrated significantly higher ESS (p < 0.001) and greater prevalence of probable RBD, RLS, and sleep apnea risk compared with controls. Tremor disability scores correlated with PSQI scores in ET-plus, suggesting an interaction between motor and non-motor burden. CONCLUSIONS: Both ET and ET plus have significant sleep dysfunction with ET-plus patients showing markedly poorer sleep quality, higher daytime somnolence, and greater parasomnia prevalence than ET and controls. These findings highlight the clinical relevance of routine sleep assessment in ET and may impact quality of life and management.