These should be replaced with higher frequency light bulbs or turned off - with natural light used instead, an education conference in London heard.
Poor classroom design and the position of equipment could also add to glare.
The findings could also help to explain why some children found reading easier when they use coloured overlays on top of books to reduce the brightness of the page, the study by a team fom the universities of Cambridge and Essex said.
The researchers measured the flicker and lighting levels in 90 classrooms at 11 secondary schools in six local authority areas.
They claimed that nine out of 10 classrooms were excessively bright.
A spokesman for the Department for Children, Schools and Families pointed out there was very comprehensive guidance on lighting and classroom design on its websites for teachers.
