The main aim of the study is to examine the effect of oral CoQ10 plus NADH (Reconnect®) supplementation twice daily for 8-weeks on the changes in fatigue perception, sleep disturbances, autonomic dysfunction and HRQoL assessed by patient-reported outcome measures in CFS/ME.

Chronic Fatigue Syndrome, as known as Myalgic Encephalomyelitis (CFS/ME) is a complex and extremely debilitating chronic condition, with no known cause, no established diagnostic tests, and no universal effective therapy. Its symptoms are mainly unexplained disabling fatigue that lasts for six months or more and that does not improve with rest, worsing with physical and mental activity. It is associated with other concomitant symptoms including muscle pain, post-exertional malaise lasting more than 24h, unrefreshing sleep, autonomic dysfunction and cognitive problems worsing quality of life of sufferers. Previous studies have shown that CFS/ME subjects have a significant decrease in CoQ10 and NADH levels in plasma and peripheral blood mononuclear cells (PBMCs), correlating with symptoms of the condition. Hypothesis: CoQ10 plus NADH administration could be beneficial in the improvement of outcome measures and molecular parameters in CFS/ME individuals.

A total of 282 potentially eligible Caucasian CFS/ME subjects who meet both the 1994 Centers for Disease Control and Prevention/Fukuda's definition and 2003 Canadian case criteria for CFS/ME will be initially enrolled in the study. Those patients who don't meet the inclusion criteria will excluded of the study. All participants will be treatment with ReConnect® containing CoQ10 (50 mg) plus NADH (5 mg) vs. placebo twice daily for 8-weeks in term. Scores for fatigue perception, sleep problems, autonomic dysfunction and QoL will be assess by validated questionnaires of Fatigue Impact Scale (FIS-40), Pittsburgh Sleep Quality Index (PSQI), COMPASS-31 and HRV recording device, and HRQoL (36 item Short Form Health survey), respectively.

The primary outcome is to evaluate the efficacy of oral CoQ10 plus NADH (Reconnect®) supplementation twice daily for 8-weeks on the changes in fatigue perception, sleep problems, autonomic dysfunction and health-related quality of life assessed by outcome measures in CFS/ME subjects.

The secondary outcomes are to examine the effect of oral Reconnect® administration on fatigue perception (assessed by FIS-40), sleep disruption (PSQI), autonomic function (COMPASS-31), Heart Rate Variability (HRV) for measuring R-R intervals by mobile device coupled to the Polar H7 thoracic belt and HRQoL (36-items Short Form Health survey).

Inclusion Criteria:

1. Patients female between 18 and 65 years old.
2. Body Mass Index (BMI) ≤ 30 mg/m²
3. Subjects who met the 1994 Centers for Disease Control and Prevention/Fukuda definition and 2003 Canadian diagnostic criteria for CFS/ME.
4. Patients must be able to participate, understand and complete questionnaires in Spanish language.
5. Patients who give a signed informed consent before initiating the study.

Exclusion Criteria:

1. Patients who do not fulfilled the 1994 Centers for Disease Control and Prevention/Fukuda definition and 2003 Canadian criteria for CFS/ME.
2. Patients who are participating in another clinical trial of the same or different nature in the last 30 days prior to inclusion.
3. Any participants who, in the opinion of the principal investigator, may not be able to follow instructions or make a good treatment compliance.
4. Subjects that don't give signed informed consent to participate in the study.
5. Participants who are receiving any drug or banned substances and is expected that withdrawal of some medications/products not allowed in the study involves a significant problem.
6. Participants who are pregnant and/or breastfeeding,
7. Participants with autoimmune disorder, cancer, endocrine and metabolic disorders, rheumatic conditions, multiple sclerosis, psychosis, major depression, cardiovascular disease, hematological conditions, use of oral anticoagulants, smokers or had a history of substance abuse.

The investigator, care provider and participants do not know which individuals have been assigned in each arm or comparison group.