The goal of this clinical trial is to learn if the OTC supplement, hydrogen water, works to treat the fatigue-related symptoms and functional limitations in adults with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). It will also examine if heart rate variability (HRV) can be used to predict who will benefit from the hydrogen water treatment. The main questions it aims to answer are:

Does the OTC supplement, hydrogen water, work to reduce the fatigue-related symptoms and improve functioning in participants who have ME/CFS?

Can HRV be used to predict who will benefit from treatment with hydrogen water?

The purpose of this pilot study is to identify a biomarker for improvement in chronic fatigue syndrome. Treatment of ME/CFS starting on 10-day graduated dosing schedule followed by a standard daily dose of hydrogen water (a magnesium-based OTC supplement) over 16 weeks is expected to yield two subgroups, improvers and non-improvers. These subgroups will be delineated by heart rate variability (HRV), a biological measure of health and well-being. Higher HRV will predict improvement and lower HRV will predict non-improvement (no change or worsening). This would be the first biomarker of improvement found in ME/CFS. If treatment is successful, subjects will experience a reduction in fatigue and an increase in physical function. Thus, the study may advance potentially an effective intervention for individuals with ME/CFS and further the understanding of the biology of favorable treatment outcomes, i.e., improved HRV status.

Inclusion Criteria: Meets Institute of Medicine criteria for myalgic encephalomyelitis/chronic fatigue syndrome -

Exclusion Criteria: Medical illness that explains presenting fatigue; Any psychosis.

-