“…In our study, lower RSA correlated with increased inflammation-related cytokines (most strongly TNFa, but also IL-6, IL1a and IFNg; not with CRP). Relationships between heart rate variability and cytokines have been reported earlier in patients with a broad range of diseases such as those with heart failure (Malave et al, 2003;Nikolic et al, 2013), obesity and diabetes (Parish et al, 2016;Wegeberg et al, 2020), obstructive sleep apnea (Xie et al, 2020), infants with hypoxic ischemic encephalopathy (Al-Shargabi et al, 2017;Yasova Barbeau et al, 2019), in traumatic brain injury (Deepika et al, 2018), to name just a few, and in larger samples of healthy subjects (Cooper et al, 2015;Lampert et al, 2008;von Kanel et al, 2008). Note that all papers cited demonstrated a low-HRV-associated-with-high-cytokines relationship, although not always using the same measures for HRV/cytokines, but according to a recent meta-analysis, SDNN and HF-HRV should show the largest effect sizes (Williams et al, 2019).…”