A training programme tested on children with mild or moderate chronic fatigue syndrome (CFS) can reduce fatigue and increase attendance at school, a small study from the University of Bristol suggests.
The Lightning Process, a type of brain therapy, was used alongside specialist medical care.
But ME charities said they did not recommend or endorse the process.
The NHS currently recommends behavioural and exercise therapy.
Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), is a disabling illness that affects 1% of secondary school children in the UK, causing them to miss a day or more of school per week.
In total, it is thought to affect 250,000 people in Britain.
Esther Crawley, lead study author and professor of child health at the University of Bristol, decided to research the Lightning Process after the parents of her patients asked her about it in her clinic.
"I have to say that I never expected it would work," she said.
What is the Lightning Process?
- a training course that teaches how to use the brain to improve the body's level of health
- it is run over three half-days in group sessions and costs about £650
- it focuses on using simple exercises, movements and gestures to help stimulate recovery
- it combines elements of osteopathy, life coaching and neurolinguistic programming
- the scientific community is sceptical of it
- no previous research had been done to investigate how effective it is
- it is not available on the NHS
For the Bristol study, published in Journal of Archives of Disease in Childhood, 51 children aged 12-18 years received standard medical care plus three days of the LP training programme, while another 49 received standard care alone.
Six months later, the group that received the additional training said they were experiencing less fatigue and anxiety and better physical function than the control group.
After a year, the training group also reported they felt less depressed and had spent more days at school, compared with the other group - who also said their symptoms had improved.
Prof Crawley said there were limitations to the study - they did not know why LP had worked and could not say whether it would help adults or younger children.
And she said more research was needed to find out if the same results could be achieved again and to understand more about the process, before it could be incorporated into NHS care.
About 250 youngsters with CFS/ME have therapy each year. Current treatments include:
- cognitive behavioural therapy
- graded exercise therapy
- activity management
Charities and campaign groups say CFS is not a mental health condition and psychological-based therapies such as the Lightning Process are not going to help.
They say people have reported spending huge amounts of money on the training with no obvious benefit, and some have even experienced worsening symptoms.
They are calling for more science-based research into the physical causes of chronic fatigue syndrome.
Dr Charles Shepherd, medical adviser for the ME Association, said: "The Lightning Process is not a treatment that we endorse or recommend for people with ME/CFS.
"It may well be that there are some people with a general fatigue state resulting from stress, emotional or psychological problems who could benefit from a 'mind over matter' retraining approach such as this."
But he said this was not to be confused with ME/CFS.
He said: "There has been a very significant growth in biomedical research globally into ME/CFS in the past decade which has demonstrated clear abnormalities in brain, muscle and immune system function.
"The over-simplistic and largely psychological model of ME/CFS causation that is being put forward to patients by Lightning Process practitioners is totally out of step with emerging scientific evidence as to its cause."
The ME Association said using children and young people with ME/CFS in trials of this nature was "unethical and potentially damaging to their lives and health".
Jane Colby, executive director of the Young ME Sufferers Trust, said: "As a former head teacher, I know that children are vulnerable, especially when they are ill.
"They desperately want to believe the adults around them, but if their body is telling them something different from what the adults are saying, the child must be in conflict about what to believe."
Action for ME said it did not recommend any single form of intervention or treatment for ME and advised people to "examine with scepticism any treatment, therapy or other approach which claims to offer a cure".
The National Institute for Health and Care Excellence announced on Tuesday that it would be revising the guidelines on the diagnosis and management of ME/CFS.