Teenagers who have a miserable time at school are more at risk of health problems in later life, new research reveals.
Girls, especially, who are bullied or ostracised have a higher chance of becoming obese, have high blood pressure and cholesterol, and developing heart disease and diabetes by their early 40s.
The Swedish study, published in the journal PLoS One, followed almost 900 students in the north of the country from 16 to 43.
And the academics, from the universities of Umea and Stockholm, said it was not only those at 'the extreme end of the spectrum', such as 'those exposed to bullying or victimisation' that tended to have worse health in middle age.
They wrote: "Our results support the notion that aspects of peer relationships are not only related to future health in the extreme end of the spectrum, eg, restricted to those exposed to bullying or peer victimization, but that one's difficulties with peers are represented by a health gradient in adulthood."
They were unsure why the effect was stronger in females, but suggested it could be because men and women had 'different life course pathways'.
The researchers concluded: "Our results corroborate the general notion that peer relationships in childhood or adolescence may impact on adult health."
The study found this link held true even after the health of the participants age 16 and their parents' social position, was taken into account.