The presence of a best friend can help you feel better during stressful times, according to a study of children. "One of the interesting things about these findings is that it's not just any friend -- it's the best friend," ," the Daily Mail quoted Ryan Adams, the study's lead author and an assistant professor of paediatrics at the Cincinnati Children's Hospital Medical Centre, as saying. A hundred children aged ten to 12 were asked to fill out a diary five times a day for four school days, and rate how they felt about what they'd experienced in the past 20 minutes. They were also asked whether they'd been alone or with parents, siblings, a best friend, a boy or girl friend, classmates, strangers, teachers or some other person. And they had saliva samples take to measure for the stress hormone cortisol. Researchers found that the presence of a best friend, more than anyone else, buffered the physical effects of a negative experience, so the child produced less cortisol. When no friend was around during times of stress, cortisol levels shot up. Although the study only looked at children, experts say its findings are likely to apply to adults too. "A child's close friends can be problematic and lead them astray, but they can also be incredibly positive and supportive"said Dr Karen Majors, an education psychologist with Barking and Dagenham Community Educational Psychology Service. "Friendships serve really important purposes socially, emotionally and cognitively as well as being a playmate and companion," he added.