Advantage in sleep phase staging evaluating heart rate variability in patients with idiopathic rapid eye movement behaviour disorder: a systematic review with meta-analysis [* Cross-Reference *]

Abstract Introduction Sleep disorders affect quality of life and represent a warning for disease. Among them, idiopathic rapid eye movement (REM) sleep behaviour disorder (iRBD) could be an early marker in the development of α-synucleopathies, including multiple system atrophy, Parkinson’s disease, and Lewy body dementia, all of which are known to affect the autonomic nervous system and consequently the cardiovascular function. The heart rate variability (HRV) analysis is a valid and non-invasive tool to characterize the autonomic nervous system at the cardiac level. While the cardiac autonomic dysfunction in the α-synucleopathies has been established, less is known about its involvement in the prodromic phase of the disease as iRBD. Purpose We conducted a systematic review with meta-analysis to investigate the role of HRV indices in differentiating patients with iRBD and healthy controls (HC) in the sleep period. Methods Three different databases (PubMed, Scopus, Embase) were appropriately screened. Studies were considered eligible if they included HRV indices in time and frequency domains, comparing them between adults with iRBD and HC in the sleep period. Included HRV indices were: mean RR interval (RR), root mean square of successive differences between adjacent RR intervals (RMSSD), total power of RR series (TP), and absolute power of the RR series in the high frequency band (HFRR). A meta-analysis was performed comparing HRV indices in iRBD patients and HC. The effect measures were estimated through the standard mean difference (SMD), along with the 95% confidence interval [CI]. Results Nine studies were selected. Seven studies separately reported HRV indices during the different sleep stages, REM and non-REM (NREM), while two reported a unique value for the whole sleep-time period. In the 7 studies where data were separately presented for each sleep stage, values were also calculated for the whole sleep-time period following indication for meta-analysis. No differences were founded in RR, RMSSD, TP, and HFRR between patients with iRBD and HC when the whole sleep period was considered. When differentiating the sleep stages, during the REM phase RMSSD was higher in HC than in the iRBD patients (SMD [95% CI]: 0.57 [0.14, 1.00], p=0.01, 94 subjects, 2 studies). During the NREM stage, TP (SMD [95% CI]: 1.36 [0.45, 2.27], p=0.004, 71 subjects, 2 studies) and HFRR (SMD [95% CI]: 0.52 [0.01, 1.04], p=0.04, 273 subjects, 6 studies) were higher in HC than in iRBD patients. Conclusion The results of the meta-analysis showed that HRV indices were useful in differentiating iRBD patients from controls, suggesting that patients are characterized by lower overall HRV and lower cardiac vagal modulation than controls. Our findings support the importance of studying the HRV indices during sleep accounting for the sleep stages. However, the paucity of the included studies prevents to draw definitive conclusions and encourages further research in this field. (2025-05-01)

***This entry has been automatically imported via OpenAlex by LIST harvest scripts. Please refer to https://doi.org/10.1093/eurjpc/zwaf236.445 for the original and latest version of the publication*** (2026-07-01)