Article Heart Rate Variability and Fatigue in Patients With Chronic Fatigue Syndrome After a Comprehensive Cognitive Behavior Group Therapy Program Anita L. Hansen, 1 Gerd Kvale, 2 Bjarte Stubhaug, 3 and Julian F. Thayer 4 1 University of Bergen, Department of Psychosocial Science and Center for Research and Education in Forensic Psychiatry, Haukeland University Hospital, Norway, 2 Department of Clinical Psychology, University of Bergen and Haukeland University Hospital, OCD-unit/Frihamnsenteret Clinic, Skånevik, Norway, 3 Section of Mental Health Research, Helse Fonna HF, Frihamnsenteret Clinic, Skånevik, Institute of Clinical Medicine, University of Bergen, Norway, 4 Department of Psychology, The Ohio State University, Columbus, OH, USA Abstract. In psychotherapy research, there is a general lack of studies that include objective measurements that provide information about the basic underlying mechanisms involved in behavioral and psychiatric conditions. In this pilot study, we investigated cardiovascular activity and self-reported fatigue in patients with Chronic Fatigue Syndrome (CFS) compared to normal healthy controls who served as a reference group. Furthermore, based on a one-group pre-post design, we investigated whether exposure to a Comprehensive Cognitive Behavior Therapy (CCBT) program resulted in any changes in cardiovascular activity and self-reported fatigue in CFS patients. Overall, 19 female CFS patients and 21 normal healthy controls were included in the study. Cardiovascular activity measurements were heart rate (HR), low frequency/high frequency (LF/HF ratio), and heart rate variability (the root mean of the squared successive differences; rMSSD). Fatigue was measured using the Chalder Fatigue Questionnaire. Analyses of the results indicated that, compared to normal healthy controls, CFS patients were characterized by higher HR and self-reported fatigue prior to exposure to the CCBT. Interestingly, CFS patients showed a significant decrease in LF/HF ratio indicating a shift in sympathovagal balance toward greater vagal activation, and levels of experienced fatigue subsequent to CCBT. Keywords: heart rate variability, chronic fatigue syndrome, therapy Chronic Fatigue Syndrome (CFS) is a heterogeneous disor- der characterized by excessive, prolonged, and disabling fatigue, pain, and somatic complaints, with functional and mental impairment and major consequences for occupa- tional and social life (Afari & Buchwald, 2003; de Lange et al., 2008; Maquet, Demoulin, & Crielaard, 2006; Prins, van der Meer, & Bleijenberg, 2006). There is also evidence of autonomic dysfunction being associated with CFS (Freeman, Anthony, & Komaroff, 1997; Wyller, Barbieri, Thaulow, & Saul, 2008; Wyller, Saul, Amlie, & Thaulow, 2007), of endocrine and immunological dysregulation (Dickson, Toft, & O’Carroll, 2009; Klimas & Koneru, 2007; Nijs et al., 2005; Torres-Harding, Sorenson, Jason, Maher, & Fletcher, 2008; Torres-Harding, Sorenson, Jason, Maher, Fletcher, et al., 2008), as well as neuropsychologi- cal dysfunction (Dickson et al., 2009). Thus, physiologi- cally the CFS condition may reflect a system under stress. CFS patients often try to cope with their illness by resting or avoiding physical activity in order to prevent their symptoms (Prins et al., 2006; Vercoulen et al., 1997), and such coping is often a dysfunctional strategy. Thus, the impaired quality of life in these patients may be escalated by their coping strategies and self-regulation. Although there are controversies in the field of chronic fati- gue, there seems to be general agreement among research- ers that CFS is a multifactorial condition to be viewed in a biopsychosocial perspective, although the bio-aspect is emphasized more than the psychosocial aspect (Maes, Hogrefe Publishing Journal of Psychophysiology 2013; Vol. 27(2):67–75 DOI: 10.1027/0269-8803/a000088 Ó 2012 Federation of European Psychophysiology Societies