Background: The patients suffering of the rapid eye movement sleep behavior disorder (RBD) are in high risk of developing a neurodegenerative disorder, most frequently from the group of alpha-synucleinopathies, such as Parkinson’s disease (PD), Dementia with Lewy Bodies (DLB) or multiple system atrophy (MSA). The definitive diagnosis of RBD is based on polysomnographic investigation. Actigraphy is much easier to perform and reflects condition in patient′s home environment. The aims: The aim of this study was to find suitable biomarkers for RBD, which can be detectable by actigraphic recording. Methods: High resolution actigraphic recording (MotionWatch, CamNtech ltd.) and confirming polysomnographic recording was performed on 45 RBD patients, 30 patients with other sleep-related motor disorders and 20 healthy controls. Each individual file was analysed by software testing for amount of sleep (MotionWare 1.1.20) and secondly for periodic motor activity (PLMS analysis 1.0.16). The 13-item patient self-rating RBD screening questionnaire (RBD-SQ) translated to Czech language was also used for screening purposes. We used an RBD-SQ score of five points as a positive test result, as suggested by the original publication of the scale. Results: When using the actigraphic sleep detection, we encountered significant differences mostly on non-dominant hand, related to sleep fragmentation – most notably increased percentage of Short immobile bouts (47.0% vs. 28.0%, p<0.0001), increased Fragmentation index (72.5 vs. 40.7, p<0.0001) and decreased percentage of Sleep efficiency (72.1% vs. 86.8%, p<0.0001)in RBD subjects compared to other sleep disorders and controls. When analyzing periodic motor activity, we also found surprisingly more periodic hand movements (p=0.028, corrected for multiple testing), but differences on lower extremities using either measurement were not significant. The discrimination function based on RBD-SQ and Short immobile bouts % could allocate correctly the RBD status in 87.6% of cases with Wilks Lambda 0.435 and p<0.0001. Conclusion: In our single-center study in patients from the Czech population, we found that actigraphic recording from upper extremities shows consistently more prominent sleep fragmentation in RBD patients compared to other sleep diagnoses or healthy controls. Actigraphy may be useful in broader screening for RBD.