ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

21–40 of 349 studies

E0 ConsensusReviewPEM not requiredMeta-Analysis

As good as it gets? A meta-analysis and systematic review of methodological quality of heart rate variability studies in functional somatic disorders.

Tak, Lineke M, Riese, Harriëtte, de Bock, Geertruida H et al.·Biological psychology·2009

This research review looked at whether people with ME/CFS and similar conditions have problems with their nervous system's ability to regulate heart rate. Researchers combined results from 23 studies involving 533 patients and found weak evidence that patients may have lower parasympathetic nerve activity (the calming part of the nervous system) compared to healthy people. However, the evidence was not strong enough to draw firm conclusions, and the studies reviewed had many quality problems that made the results unreliable.

Autonomic Nervous System

E0 ConsensusReviewPEM not requiredEditorial

Central nervous system abnormalities in fibromyalgia and chronic fatigue syndrome: new concepts in treatment.

Gur, Ali, Oktayoglu, Pelin·Current pharmaceutical design·2008

This review examines how ME/CFS and fibromyalgia may both involve problems in the nervous system—specifically in how the brain processes pain, manages stress hormones, and controls automatic body functions. The authors discuss why current treatments are limited and explore new medication approaches that target brain chemicals involved in pain and fatigue.

SleepAutonomic Nervous SystemCognitive Impairment

E0 ConsensusReviewPEM not requiredReview-Narrative

Dysautonomias: clinical disorders of the autonomic nervous system.

Goldstein, David S, Robertson, David, Esler, Murray et al.·Annals of internal medicine·2002

This review examines dysautonomias—conditions where the autonomic nervous system (the part of your body that controls heart rate, blood pressure, and other automatic functions) stops working properly. The authors discuss how these problems can range from occasional fainting spells to serious nerve damage. Importantly, they note that ME/CFS patients often show signs of orthostatic intolerance (difficulty maintaining blood pressure when standing), but a common treatment that works for other autonomic conditions does not appear to help ME/CFS patients.

Autonomic Nervous System

E0 ConsensusReviewPEM not requiredEditorial

Chronic fatigue syndrome: what role does the autonomic nervous system play in the pathophysiology of this complex illness?

Gerrity, Timothy R, Bates, Janet, Bell, David S et al.·Neuroimmunomodulation·2002

This paper brings together expert opinions about how the autonomic nervous system (the part of your nervous system that controls automatic functions like heart rate and breathing) may be involved in ME/CFS. The authors reviewed what was known in 2000 about connections between autonomic nervous system problems and other system dysfunctions seen in ME/CFS, including immune and hormone abnormalities.

Autonomic Nervous System

E0 ConsensusReviewPEM not requiredReview-Narrative

Autonomic nervous system derangement in fibromyalgia syndrome and related disorders.

Cohen, H, Neumann, L, Kotler, M et al.·The Israel Medical Association journal : IMAJ·2001

This review examines how the autonomic nervous system—the part of your nervous system that controls heart rate, breathing, and digestion automatically—may not work properly in fibromyalgia and related conditions like ME/CFS and irritable bowel syndrome. Researchers found evidence that this system dysfunction could have important health consequences, including increased risk of heart problems. However, studies on this topic have produced mixed and sometimes contradictory results.

Autonomic Nervous System

E0 ConsensusReviewPEM not requiredReview-Narrative

Controlled exposures to volatile organic compounds in sensitive groups.

Fiedler, N, Kipen, H M·Annals of the New York Academy of Sciences·2001

This review looked at studies where people with chemical sensitivities were exposed to different odors and chemical mixtures in controlled lab settings. Researchers found that people with chemical sensitivities did have real symptoms when exposed to certain chemicals, even at low levels, but these symptoms weren't always linked to measurable changes in heart rate, breathing, or other body functions that usually indicate stress.

Autonomic Nervous System

E0 ConsensusReviewPEM not requiredReview-Narrative

Chronic pain and fatigue syndromes: overlapping clinical and neuroendocrine features and potential pathogenic mechanisms.

Clauw, D J, Chrousos, G P·Neuroimmunomodulation·1997

This review examines fibromyalgia and chronic fatigue syndrome, two conditions with overlapping symptoms of pain and exhaustion that have been described throughout medical history under different names. The authors propose that both conditions stem from problems in the central nervous system—the brain and spinal cord—particularly in areas that control hormone levels, pain sensing, and automatic body functions. They suggest that immune system changes seen in these conditions are side effects rather than root causes.

Autonomic Nervous SystemImmune System

E1 ReplicatedTrialPEM unclearRCT

The Use of Heart Rate Variability-Biofeedback (HRV-BF) as an Adjunctive Intervention in Chronic Fatigue Syndrome (CSF/ME) in Long COVID: Results of a Phase II Controlled Feasibility Trial.

Cossu, Giulia, Kalcev, Goce, Primavera, Diego et al.·Journal of clinical medicine·2025

This study tested whether a technique called heart rate variability biofeedback (HRV-BF)—which uses breathing exercises and computer feedback to help regulate your nervous system—could help people with Long COVID who have severe fatigue. Participants received 10 sessions over 5 weeks, and the results showed that people in the treatment group experienced greater improvement in severe fatigue compared to those receiving usual care. The treatment was well-tolerated with very few people dropping out, suggesting it could be a helpful add-on therapy for ME/CFS.

Autonomic Nervous System

E1 ReplicatedTrialPEM not requiredRCT

Effects of acupuncture and moxibustion on heart rate variability in chronic fatigue syndrome patients: Regulating the autonomic nervous system in a clinical randomized controlled trial.

Li, Tong, Litscher, Gerhard, Zhou, Yudian et al.·Complementary therapies in medicine·2025

This study tested whether acupuncture and moxibustion (a traditional heat therapy) could help people with chronic fatigue syndrome by measuring changes in heart rate variability, which reflects how well the nervous system is working. Researchers divided 175 CFS patients into groups receiving different acupuncture treatments, fake acupuncture, or moxibustion over 10 sessions. Both acupuncture and moxibustion reduced fatigue symptoms, with combining both approaches working best, and the treatments appeared to help balance the body's stress response system.

Autonomic Nervous System

E1 ReplicatedTrialPEM requiredRCT

Assessing fatigue in myalgic encephalomyelitis/chronic fatigue syndrome patients before and after treatment with bright light therapy: A prospective randomized controlled crossover study.

Ludwig, Birgit, Hauer, Lea, Böck, Marion et al.·Sleep medicine·2025

Researchers tested whether bright light therapy—using special light boxes at home for two weeks—could help reduce fatigue in ME/CFS patients. While fatigue scores did improve immediately after the light therapy, these improvements did not remain significant when compared fairly to a waitlist control group. The study did find that bright light therapy may have helped patients concentrate better and react faster to tasks.

Autonomic Nervous SystemCognitive Impairment

E1 ReplicatedTrialPEM unclearRCT

Compression Stockings Improve Cardiac Output and Cerebral Blood Flow during Tilt Testing in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) Patients: A Randomized Crossover Trial.

van Campen, C Linda M C, Rowe, Peter C, Visser, Frans C·Medicina (Kaunas, Lithuania)·2021

Many ME/CFS patients experience dizziness and other symptoms when standing up (called orthostatic intolerance). This study tested whether compression stockings—tight socks that squeeze the legs—could help. Researchers found that when ME/CFS patients wore compression stockings during a standing test, their heart pumped blood more effectively and their brain received better blood flow compared to when they wore regular socks.

Autonomic Nervous System

E1 ReplicatedCohortPEM requiredObservational

Cerebral blood flow is reduced in ME/CFS during head-up tilt testing even in the absence of hypotension or tachycardia

C. M. C. van Campen, F. C. Visser, P. C. Rowe·Journal of Internal Medicine·2020·n=429

In the largest study of its kind, 429 ME/CFS patients underwent head-up tilt testing with simultaneous cerebral blood flow monitoring. Nearly all ME/CFS patients showed significantly reduced cerebral blood flow when upright, even when blood pressure and heart rate were normal. The reduction correlated with symptom severity.

Autonomic Nervous SystemCognitive Impairment

E1 ReplicatedTrialPEM not requiredRCT

Ubiquinol-10 supplementation improves autonomic nervous function and cognitive function in chronic fatigue syndrome.

Fukuda, Sanae, Nojima, Junzo, Kajimoto, Osami et al.·BioFactors (Oxford, England)·2016

This study tested whether taking a supplement called ubiquinol-10 (a form of coenzyme Q10) could help people with ME/CFS feel better. Researchers first gave 20 patients ubiquinol-10 for 8 weeks and saw improvements, then tested it more rigorously in 43 patients who either received ubiquinol-10 or a placebo for 12 weeks. The results suggested that ubiquinol-10 may help improve some CFS symptoms, particularly problems with nerve function and thinking ability.

Autonomic Nervous System

E1 ReplicatedTrialPEM not requiredRCT

Acupuncture and Moxibustion have Different Effects on Fatigue by Regulating the Autonomic Nervous System: A Pilot Controlled Clinical Trial.

Shu, Qing, Wang, Hua, Litscher, Daniela et al.·Scientific reports·2016

This study tested whether two traditional Chinese medicine treatments—acupuncture and moxibustion (warming therapy)—could help reduce fatigue in ME/CFS patients. Forty-five people were divided into three groups: two received acupuncture and one received moxibustion. Both treatments reduced fatigue, but moxibustion appeared to work better, especially over the long term, possibly by calming the nervous system.

Autonomic Nervous System

E1 ReplicatedTrialPEM not requiredRCT

Effects of low-dose clonidine on cardiovascular and autonomic variables in adolescents with chronic fatigue: a randomized controlled trial.

Fagermoen, Even, Sulheim, Dag, Winger, Anette et al.·BMC pediatrics·2015

This study tested whether a low-dose blood pressure medication called clonidine could help adolescents with ME/CFS, particularly those experiencing dizziness when standing up. Researchers found that clonidine did reduce certain stress hormones in the blood and improved some measurements of heart rhythm control while lying down, but it did not relieve the actual symptoms of dizziness or improve heart function during positional changes.

Autonomic Nervous System

E1 ReplicatedTrialPEM not requiredRCT

Home orthostatic training in chronic fatigue syndrome--a randomized, placebo-controlled feasibility study.

Sutcliffe, K, Gray, J, Tan, M P et al.·European journal of clinical investigation·2010

Some ME/CFS patients experience sudden drops in blood pressure when standing up, which may worsen fatigue. This study tested whether daily tilting exercises done at home could help stabilize blood pressure and improve symptoms. Over 6 months, patients who did the tilting exercises showed slightly better blood pressure control compared to those doing fake exercises, though fatigue improvements were modest.

Autonomic Nervous System

E1 ReplicatedTrialPEM not requiredRCT

Combination therapy with hydrocortisone and fludrocortisone does not improve symptoms in chronic fatigue syndrome: a randomized, placebo-controlled, double-blind, crossover study.

Blockmans, Daniel, Persoons, Philippe, Van Houdenhove, Boudewijn et al.·The American journal of medicine·2003

Researchers tested whether a combination of two medications (hydrocortisone and fludrocortisone) could reduce fatigue and improve well-being in ME/CFS patients. Over 6 months, 80 patients took either the medication combination or placebo in a blinded study where neither patients nor doctors knew which they were receiving. The medications did not help—patients reported the same level of fatigue and well-being whether they were taking the drugs or placebo.

Autonomic Nervous System

E1 ReplicatedTrialPEM not requiredRCT

Fludrocortisone acetate to treat neurally mediated hypotension in chronic fatigue syndrome: a randomized controlled trial.

Rowe, P C, Calkins, H, DeBusk, K et al.·JAMA·2001

Many people with ME/CFS experience a drop in blood pressure when standing up (called neurally mediated hypotension), which may contribute to symptoms like dizziness and fatigue. This study tested whether a medication called fludrocortisone could help reduce ME/CFS symptoms in 100 patients with this blood pressure problem. After 9 weeks of treatment, the medication did not work better than placebo, suggesting it may not be an effective standalone treatment for this group.

Autonomic Nervous System

E1 ReplicatedTrialPEM not requiredRCT

A preliminary placebo-controlled crossover trial of fludrocortisone for chronic fatigue syndrome.

Peterson, P K, Pheley, A, Schroeppel, J et al.·Archives of internal medicine·1998

This study tested whether a low-dose steroid medication called fludrocortisone could help ME/CFS patients feel better. Twenty participants took either the medication or a placebo for 6 weeks each, in random order. The medication did not improve fatigue, other symptoms, or physical function compared to placebo, and it did not cause more side effects than placebo.

Autonomic Nervous System

E2 ModerateCohortPEM unclearLongitudinal

Two-timepoint multidomain follow-up of post-COVID condition and ME/CFS: overlapping autonomic, small-fiber, and cognitive changes.

Azcue, N, Barranco, C, Tijero-Merino, B et al.·Journal of translational medicine·2026

Researchers compared 21 people with post-COVID condition and 17 people with ME/CFS over about 2.5 years, measuring nerve function, autonomic symptoms, and cognitive performance. They observed that both groups showed similar patterns of changes over time—including worsening processing speed and cold sensation sensitivity, but improving heat sensation thresholds and verbal memory. While the two conditions appeared increasingly alike on follow-up testing, the study does not establish whether they are truly the same disease or simply share overlapping symptoms.

Pain and SensitizationAutonomic Nervous SystemDiagnosticsCognitive Impairment

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As good as it gets? A meta-analysis and systematic review of methodological quality of heart rate variability studies in functional somatic disorders.

Central nervous system abnormalities in fibromyalgia and chronic fatigue syndrome: new concepts in treatment.

Dysautonomias: clinical disorders of the autonomic nervous system.

Chronic fatigue syndrome: what role does the autonomic nervous system play in the pathophysiology of this complex illness?

Autonomic nervous system derangement in fibromyalgia syndrome and related disorders.

Controlled exposures to volatile organic compounds in sensitive groups.

Chronic pain and fatigue syndromes: overlapping clinical and neuroendocrine features and potential pathogenic mechanisms.

The Use of Heart Rate Variability-Biofeedback (HRV-BF) as an Adjunctive Intervention in Chronic Fatigue Syndrome (CSF/ME) in Long COVID: Results of a Phase II Controlled Feasibility Trial.

Effects of acupuncture and moxibustion on heart rate variability in chronic fatigue syndrome patients: Regulating the autonomic nervous system in a clinical randomized controlled trial.

Assessing fatigue in myalgic encephalomyelitis/chronic fatigue syndrome patients before and after treatment with bright light therapy: A prospective randomized controlled crossover study.

Compression Stockings Improve Cardiac Output and Cerebral Blood Flow during Tilt Testing in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) Patients: A Randomized Crossover Trial.

Cerebral blood flow is reduced in ME/CFS during head-up tilt testing even in the absence of hypotension or tachycardia

Ubiquinol-10 supplementation improves autonomic nervous function and cognitive function in chronic fatigue syndrome.

Acupuncture and Moxibustion have Different Effects on Fatigue by Regulating the Autonomic Nervous System: A Pilot Controlled Clinical Trial.

Effects of low-dose clonidine on cardiovascular and autonomic variables in adolescents with chronic fatigue: a randomized controlled trial.

Home orthostatic training in chronic fatigue syndrome--a randomized, placebo-controlled feasibility study.

Combination therapy with hydrocortisone and fludrocortisone does not improve symptoms in chronic fatigue syndrome: a randomized, placebo-controlled, double-blind, crossover study.

Fludrocortisone acetate to treat neurally mediated hypotension in chronic fatigue syndrome: a randomized controlled trial.

A preliminary placebo-controlled crossover trial of fludrocortisone for chronic fatigue syndrome.

Two-timepoint multidomain follow-up of post-COVID condition and ME/CFS: overlapping autonomic, small-fiber, and cognitive changes.

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