“…Scholars have used RMSSD, for example, to study sleepiness and drowsiness (for a recent review, see Matuz et al, 2020), self-regulation (e.g., Zahn et al, 2016), and stress recovery (e.g., Loerbroks et al, 2010) . Most of these studies have been conducted in laboratories (e.g., Burlacu et al, 2021; Kaida et al, 2007) and a few in real-road driving studies (Buendia et al, 2019; Jung et al, 2014; Persson et al, 2020). Repeated HRV monitoring in office-based field studies, however, is still scarce.…”