All participants underwent a standardized psychosocial laboratory stress protocol. The TSST consists of an introduction (Intro) that lasts 2 minutes in which participants are introduced to the procedure of the TSST. Specifically, they are told that the TSST consists of a public speaking task followed by a mental arithmetic task in front of an audience. In the public speaking task (lasting 5 minutes), participants are asked to apply for a job. In this simulated job interview, they are asked to talk about their personal qualifications for the chosen job, e.g. why they are a better fit for the job than other applicants. Right after the job interview, participants are explained the nature of the mental arithmetic task, which lasts for another 5 minutes. The participants have to calculate backwards in steps of 17 from the number 2043. After each calculation error the participants are asked to re-start calculating from 2043. The TSST has repeatedly been found to be a reliable tool to activate both the HPA axis and the autonomous nervous system (ANS) [51]. In the current study, the standard TSST procedure as reported in the literature was slightly modified: in the Intro, the subjects were not told about the exact nature of the upcoming speaking task (i.e. giving a speech as part of a simulated job interview) in order to prevent subjects from mentally preparing for the task.