Chronic fatigue syndrome is going unidentified in hundreds of children, leading them to miss school, a new report claims.
A study published in the British Medical Journal found the illness could be keeping one in every 100 children out of education. Previous research estimated only between 0.1% and 0.5% of schoolchildren were affected by the condition.
The researchers studied 2,855 pupils at three schools in Bath and found 28 of them missed classes with the chronic fatigue syndrome - also known as Myalgic Encephalomyelitis (ME).
The cause of the condition is still unknown and there is no medical cure. It results in extreme fatigue and can affect memory and concentration. The illness was found to account for more than 6% of pupils who were missing "large amounts" of school.
Felicity, a 23-year-old from Birmingham, suffered from the condition from the age of 14 until she was 16 years old.
"50% of the difficulty in dealing with ME is trying to get people to understand it is a real illness. I used to tell me teacher I was tired and she would say 'We're all tired'.
"Sometimes it was a struggle even to put one leg in front of the other," she added.
Lead author of the report Dr Esther Crawley said it is an "important cause of unexplained absence from school".
"There are several possible reasons why children missing significant amounts of school with chronic fatigue syndrome/ME are not identified", she continued.
"Those with moderate/mild symptoms may not see their GP or may not be recognised as having the condition if they are seen."