Children who drink lots of caffeine-laden fizzy drinks are at greater risk of mental health problems in later life.
Scientists believe that by preventing deep sleep, caffeine interferes with the development of the brain during adolescence.
This is a critical time for the brain, when problems in development can lead to schizophrenia, anxiety, drug use and personality disorders.
Researchers experimented on rats, but say the findings raise concerns for children and teenagers, some of whom consume large amounts of caffeine from colas and energy drinks.
Between 300 and 400mg of caffeine – four cans of energy drink a day or three or four mugs of coffee – could make a difference, the study suggests.
A can of the popular energy drink Red Bull, for example, contains 80mg.
A spokesman for the