This study investigates how adolescents' daily prosocial behaviors to friends are related to diurnal cortisol using between- and within-subject analyses. Further, we examine whether role fulfillment (i.e., feeling like a good friend) moderates links between prosocial behaviors and cortisol. Ethnically diverse adolescents (N = 370; ages 11–18) reported whether they provided instrumental and emotional support to friends for 5 days, and provided four saliva samples/day for 4 days. On the daily level, providing emotional support predicted lower cortisol awakening response the next day, and providing instrumental assistance to friends was associated with a flatter cortisol slope the same day (a cardiovascular risk factor). Adolescents also provided more emotional support on days they had lower CAR and steeper cortisol slopes. On the average level, providing more instrumental support was associated with steeper cortisol slopes among adolescents who felt high levels of role fulfillment, but not among adolescents who felt low levels of role fulfillment. Providing instrumental support may be physiologically taxing from day to day but, across the long term, linked to lower cardiovascular risk for adolescents who experience helping as highly fulfilling.

中文翻译：

---

每天向朋友提供工具和情感支持与青春期的昼夜皮质醇有关

本研究使用受试者间和受试者内分析，调查青少年对朋友的日常亲社会行为与昼夜皮质醇的关系。此外，我们研究了角色履行（即感觉像一个好朋友）是否会调节亲社会行为和皮质醇之间的联系。种族多样化的青少年（N = 370; 11-18 岁）报告了他们是否为朋友提供了 5 天的工具和情感支持，并在 4 天内提供了 4 个/天的唾液样本。在日常水平上，提供情绪支持可预测第二天的皮质醇觉醒反应较低，向朋友提供工具性帮助与当天皮质醇斜率较平（心血管危险因素）相关。青少年在 CAR 较低和皮质醇斜率较陡的日子里也提供了更多的情感支持。在平均水平上，提供更多的工具性支持与感觉高度角色实现的青少年的皮质醇斜率更陡相关，但在感觉角色实现水平低的青少年中则不然。提供工具性支持可能每天都在生理上繁重，但从长远来看，