are prone to error. Importantly, the study performed by Gerbin recommended a combination of sleep diaries and polysomnography be used in future studies to investigate sleep problems in patients with ET. 6 The aim of our study was to evaluate sleep disturbances and sleep-related events in patients with ET, PD, and controls, using both self-assessment tools and polysomnographic readings. METHODS Study SampleThe ethics committee of Bülent Ecevit University approved this prospective study, and informed consent was obtained from all participants. Between 2010 and 2012, 21 patients with PD who fulfi lled the Parkinson Disease Society Bank criteria, 9 and 16 patients with ET who fulfi lled Movement Disorders BRIEF SUMMARY Current Knowledge/Study Rationale: Sleep problems in ET and PD patients had been investigated in few studies by using subjective assessment tools like self-report questionnaires previously. This study was conducted to evaluate and to compare sleep problems in these two common movement disorders by using PSG which is an objective assessment tool. Study Impact: This study will improve the knowledge about sleep problems in ET and PD patients. Furthermore this is the fi rst study comparing sleep problems in ET and PD patients using PSG.Objective: Sleep problems are a common non-motor complication of Parkinson disease (PD), and patients with essential tremor (ET) share a number of motor and non-motor features of PD. To clarify the relationship between these disorders, we evaluated the sleep problems in patients with ET and PD using assessment scales and objective polysomnographic (PSG) testing. Method: Twenty-one consecutive patients with PD, 16 with ET, and 14 healthy subjects participated in this study and were compared in terms of sleep related complaints, fi nal sleep related diagnosis, and polysomnographic features. Results:The results of our study have shown that patients with PD were more likely than were those with ET to have a history of REM sleep behavior disorders (RBD) (p = 0.001) and excessive daytime sleepiness (p ≤ 0.05). Additionally, PSG data revealed that ET patients had lower mean SpO 2 values (p ≤ 0.05) and REM without atonia (RWA) (p = 0.032) than did patients with PD. Conclusion: This is the fi rst study to use PSG to evaluate sleep problems both in ET and PD patients. The results point out different sleep problems in these two common movement disorders which should be investigated in further studies. Keywords: essential tremor, Parkinson disease, sleep, REM behavior disorder (RBD), REM without atonia (RWA) Citation: Barut BO, Tascilar N, Varo A. Sleep disturbances in essential tremor and Parkinson disease: a polysomnographic study.