The discovery, made during experiments by the Medical Research Council, builds on previous work which revealed that pupils with a reading problem which makes words seem to "wriggle" on the page can also be helped to conquer their difficulties using the sheets.
Psychologists from the council's applied psychology unit in Cambridge made the latest breakthrough after testing children in schools in Cambridge and Norfolk.
In 15 Norfolk schools, all the eight-year-olds were asked to choose from a selection of tinted plastic sheets, known as overlays, to see which, if any, made reading clearer and easier. They were then timed as they read a series of random words on a printed card, both with and without the overlays. If they wished, they were permitted to keep the sheets - found to make a difference by more than half the children - and use them while reading in school.
Identical tests given to pupils at the start of the experiment last autumn and in June revealed that around one-fifth were able to read more quickly with the overlay than without. Meanwhile, those in a control group who had seemed to need overlays but had been denied them showed a deterioration in their reading rate. Those who had struggled most with reading were more likely to choose an overlay to help.
The project, headed by Arnold Wilkins of the Cambridge applied psychology unit, was led in Norfolk by David Pointon, head of the country's sensory support service. The results had been "dramatic", Mr Pointon said.
Norfolk already leads the field among local education authorities in using overlays to help children who are experiencing some reading difficulties. Research carried out in New Zealand and the United States prompted the authority six years ago to explore the potential of the coloured sheets. "Children were coming to us and saying letters moved or jiggled and of course, in common with lots of other people, we were saying `Are you sure?'," Mr Pointon said. "But then we began to hear more about this research and became less sceptical about it."
Children with a condition known as "visual perception difficulty" see letters appear to move and create stripes and patterns rather than clear text. One boy referred to Mr Pointon described what he saw as "the letters getting up and running round the page".
In Norfolk, pupils suffering serious problems have been given overlays to use over their schoolbooks. If they continue to rely on the sheets, they are sent to an optician to be prescribed glasses with tinted lenses.
Researchers are also examining the role of coloured plastic sheets in tackling migraines. Bruce Evans, of the Institute of Optometry in London, said: "Some people get migraines when light is a trigger and they may also be helped by coloured filters, perhaps in glasses."
He added: "The weird thing about this is different people need different colours and sometimes the colour a person needs can be quite specific. They may need a blue filter but if it's light blue instead of dark it won't help them."Reuse content