BBC News Health Reporter
Saphira is now training to be a teacher
Two years ago Saphira van den Dam was too tired to do anything but sleep. She did not go to school and could not even shower without the help of her mother.
But now the 17-year-old Dutch girl, who had chronic fatigue syndrome (CFS), is back in full-time education, training to become a primary school teacher and enjoying a full social life.
She credits a form of psychotherapy for her dramatic recovery.
And the centre which pioneered it, the Expert Centre for Chronic Fatigue, in Nijmegen in the Netherlands, is so pleased with the results of its trial that it intends to introduce the therapy as part of its regular treatments.
Saphira was one of 71 adolescents aged 10-17 years with CFS contacted by the centre to take part in its trial.
Half the children were given 10 one-to-one sessions of cognitive behavioural therapy (CBT) over a period of five months, and the other half were put on a waiting list.
All were assessed after five months and the patients in the therapy group reported a significantly greater decrease in fatigue severity and functional impairment, while their attendance at school increased significantly.
"They also reported a significant reduction in other symptoms, such as impaired concentration, muscle pain, and headache.
Saphira says she was amazed by her recovery.
"Before I went there I was very tired and could not do anything. When I wanted to shower or to do anything I had to ask my Mum for help. I could not even walk up the stairs and just lay on my bed.
"I didn't know what it was and I was afraid I thought that I was going to die.
"I missed three-quarters of my school year. I still managed to pass my exams, but my teachers had to help me a lot."
Just months later she was starting to get her life back on track.
"The therapy really helped me and my family. We did a lot of talking and they helped me with my lessons by telling me to try to go back at first for one or two hours and then to go back to school properly.
"Before this I felt my life was a circle and when I felt ill I thought the circle was beginning again. But they helped me to get out of it by trying to do things.
"A few weeks after starting the treatment I went for my first lesson and I was very tired, but I went. The next day I went to school again and it all helped me to build up my strength.
"I feel a lot happier now. Whatever I want to do I can so. Sometimes I do feel a bit tired, but then I go to sleep and I am OK again."
Gijs Bleijenberg, Professor of Psychology, Head of the Expert Centre Chronic Fatigue, University Medical Centre Nijmegen, Netherlands said they had very pleased with the results.
"We have now integrated this type of therapy into our expert centre and have it as normal treatment.
"This was the first randomised control trial which has been used to show that cognitive behaviour therapy can be effective in helping children with CFS.
"We are pleased with the results.
"Although the natural course of CFS in children is much more favourable than in adults, children with CFS are severely threatened in their normal development by it.
"It is very important that there is now an effective treatment available."
He said that after the centre enrolled the adolescents onto their trial they made sure they had got the parents on board as well.
Dr Bleijenberg said parents were very influential and it was important they were fully aware of treatments and could help children to implement them.
He said that an important starting point of the therapy was to explain to parents and the child with CFS that the event that triggered their illness, such as a virus had now passed and that it was not necessary to adapt their behaviour to that situation anymore.
"If you have a virus and become tired, you start to behave in a certain way. You become inactive and rest, but as time goes on this behaviour becomes dysfunctional because it becomes perpetuating behaviour."
The therapist helps the child and also the parents to detect the behaviour that causes the problems. After that, an activity program is used to gradually increase the physical, mental and social activities.
Children were asked what their goals for recovery were and the therapist would help them work towards these step by step. Return to school is always one of the goals.
Professor Bleijenberg said some children had become totally inactive following their illness and others were trying to do too much. Both groups had to re-learn their strength and slowly start to build up.
"Part of the therapy is a plan to resume school activities. We help them to make a plan of how to do this.
"Mostly in Holland, patients go to school by bike and we help them build up to this, by talking to them about it and helping them plan their futures. We help them to gradually increase their levels of activity and go back to full time school again."
Chris Clarke, chief executive of Action for ME and Mary-Jane Williams at the Association for Young People with ME said: "CBT can help some children particularly those who are mildly or moderately affected , but no-one would regard CBT as a cure for ME."
The study was published in the British Medical Journal.