Chronic fatigue syndrome/Myalgic encephalomyelitis (CFS/ME) can be a serious and disabling condition with a heavy symptom burden and low function. Work disability is common, and social life dramatically affected. CFS/ME is a challenging health problem as well as a societal problem.

In recent years, a doubling of the number of patients with a CFS/ME diagnoses has been reported in Norway. The patient group represents a challenge for the health care system, the municipality, and the Norwegian Labour and Welfare Organization (NAV). According to new figures, the NAV pays 100 million Norwegian Kroner (NOK) each month in permanently incapacitated expenses for people with CFS/ME. Municipalities have expenses in form of care, rehabilitation and other measures.

There is a lack of effective treatment for CFS/ME. Evidence-based knowledge is highly needed.

If the 3-day course shows promising effects, this could have positive consequences for patients, relatives and health personnel, but also financially for the society and the municipality.

This is a randomized controlled trial (RCT) to investigate potential effects (positive and negative) of a 3-day course with follow-up for 100 adults with CFS/ME.

The 3-day course used in this trial is named the Lightning Process (LP). The course is built on the LP manual (Parker, 2013) and includes stress theory, Positive Psychology and knowledge about regulating thoughts, feelings and behavior, and through that positively influencing physiology.

Positive and negative effects of the course on symptoms, disability and quality of life will be investigated, and a long-term follow-up of work participation conducted.

Any adverse events experienced during or after the 3-day course will be handled according to protocol.

Inclusion Criteria:

• CFS/ME diagnosis based on the Canada Consensus Criteria.
• At least 50% out of school/work.
• Readiness to change (corresponding to the preparation phase in transtheoretical model)
• Has given informed consent.

Exclusion Criteria:

• Assessed by a General Practitioner (GP):
• Underlying physical illness or mental disorder that may explain the symptoms.
• Suicide risk/previous suicide attempts.
• Pregnancy.
• Bedridden and in need of continuous care.
• Insufficient Norwegian speaking or writing skills to participate in the 3-day course and fill out questionnaires.

The study protocol, along with the intervention protocol, will be published and publicly available. Registry data will not be shared as this is not allowed to share according to Norwegian law. However, Anonymized data can be shared with other researchers on reasonable request for use in specific research projects on CFS/ME after this study has been published. Due to privacy concerns, the complete data files will not be shared online.

The study protocol and the intervention protocol will be publicly available upon study completion.

Anonymized data involving self-report data will be shared upon reasonable request from other researchers for use in specific research projects on CFS/ME when the main analyses are completed and published.

The intervention group vs. waiting list control group status will be known to the participants and the personnel delivering the 3-day course. However, the investigator and outcome assessor will be masked to the conditions.