Heart rate variability

Heart rate variability (HRV) is a measurement of the specific changes in time (or variability) between successive heart beats. This is related to autonomic and cardiovascular function.

Notable studies related to ME/CFS

 * 2010, Reduced heart rate variability predicts poor sleep quality in a case-control study of chronic fatigue syndrome
 * 2013, Heart rate variability in patients with fibromyalgia and patients with chronic fatigue syndrome: a systematic review. (Abstract)
 * 2018, Cerebral Blood Flow and Heart Rate Variability in Chronic Fatigue Syndrome: A Randomized Cross-Over Study (Full Text)

Learn more

 * 2016, Your Crash in a Graph? How Heart Rate Variability Testing Could Help You Improve Your Health