Author	B. Serwinski
Author	A. Steptoe
Abstract	The conventional sources to assess cortisol levels are saliva, plasma or urine specimens, which are subject to a variety of factors and provide only momentary cortisol exposure. A rather new technique is the analysis of hair cortisol which might overcome some of the methodological issues associated with the other specimens. The aim of the PhD was two-fold. Firstly, I investigated the associations between hair cortisol concentration and different socioeconomic factors, work-related stress and psychosocial factors. Study I employed a design with two time points four years apart and therefore was able to evaluate psychosocial and socioeconomic factors cross-sectionally and as a dynamic entity. Lower income and worsening income change was associated with elevated hair cortisol. Moreover, an effect of status incongruity, a mismatch between education and income, on hair cortisol was found. Study III looked at the impact of examination stress on cortisol in hair and saliva in medical and law students. The student groups differed slightly in their hair cortisol levels at baseline and also in levels of anxiety, impeding proper conclusive findings. Perceived stress and anxiety were not related to hair cortisol but to salivary cortisol. The use of avoidant coping mechanisms was associated with elevated hair cortisol levels. My second aim was to evaluate the long-term consistency of cortisol in saliva and hair and also saliva-hair correlations over corresponding time-intervals. Using two distinct longitudinal studies (Study I and II), the findings indicate that a flatter rate of decline in salivary cortisol over the day was associated with elevated hair cortisol concentrations several years later, 4 (female sample) and 8 years ago (in men only), while no relationship could be found between hair cortisol in relation to the AUC and the CAR. Another dataset (Study III) assessing salivary and hair cortisol over corresponding intervals revealed positive associations between the AUC and hair cortisol.