One in four children in the second and third year of primary school said they feel stressed "often" or "very often" according to the study, released Wednesday by the German child protection association (DKSB) and the PROSOZ institute for social research.
School was identified as the biggest source of stress, with a third of children saying they felt pressured at school, while one in six got stressed by their families.
"We were particularly surprised that school causes stress so early and among a relatively large proportion of children," said Anja Beisenkamp, one of the authors of the study, which questioned nearly 4,700 children in 11 German states.
The survey also found that seven-to-nine-year-olds do not necessarily switch on the TV or the computer to relax. More than half said they went out to play or read or drew pictures indoors to relax.
Around 40 percent said they played computer games to relax, while another 13 percent said they did not know what they should do to relax.
The study also looked into what children knew about living a healthy lifestyle and nutrition.
"Unfortunately far too many children get their knowledge of health issues from adverts," said Dietrich Grönemeyer, one of the study's academic advisors. He said schools should help in this area.
One particular cause for concern was that as many as one in five children never or rarely ate breakfast before school.