Chris Keates, general secretary of the NASUWT, likened the caffeinated refreshments to ‘readily available legal highs’.
Some children drink ‘excessive’ amounts of Red Bull, Monster and Relentless, causing ‘hyperactivity’ and an ‘inevitable crash’ later, the teaching union said.
Of the 3,500 teachers it surveyed, 13 per cent cited ‘use of caffeine and energy drinks … as a driver of poor pupil behaviour’.
The teaching union is now working with national drug and alcohol charity, Swanswell, to provide pupils, parents and schools with advice on energy drinks.
The move comes as doctors warned last week that the drinks can trigger heart problems in healthy teenagers.
Miss Keates said: ‘This is the first time we have seen a significant number of teachers beginning to raise this as a concern. These drinks are becoming increasingly popular among young people and are often seen as simply like any other soft drink, but many young people and their parents are not aware of the very high levels of stimulants that these drinks contain.’
She added: ‘Teachers are growing increasingly concerned that some young people are using these drinks to enable them to stay up into the early hours of the morning and then replace their lost energy by drinking two or three cans of these drinks on their way to school.
‘Teachers are reporting that this affects concentration in class and hyperactivity is then followed by the inevitable crash later in the school day when the impact of these drinks wear off. Parents and young people need to be made aware of what these drinks contain and their potential impact on behaviour.’
