Emotion regulation and diurnal cortisol: A longitudinal study of early adolescents.

Aberrant patterns of diurnal cortisol, a marker of stress reactivity, predict adverse physical and mental health among adolescents. However, the mechanisms underlying aberrant diurnal cortisol production are poorly understood. Thus, the objective of this study was to investigate, for the first time, whether the core emotion regulation (ER) strategies of rumination (brooding, reflection), reappraisal, and suppression were prospectively associated with individual differences in diurnal cortisol during the COVID-19 pandemic, a period of significant stress. A community sample of 48 early adolescents (Mage = 13.45; 60% males) was recruited from British Columbia, Canada. Participants completed ER measures before the pandemic, and diurnal cortisol was assessed by collecting eight saliva samples over two days during the first COVID-19-related lockdown in the region. As expected, brooding predicted elevated waking cortisol and a blunted cortisol awakening response (CAR), whereas reflection predicted lower waking cortisol and suppression predicted a steeper CAR. Unexpectedly, reappraisal was not associated with diurnal cortisol production. Results indicate that ER strategies may represent a mechanism underlying individual differences in biological markers of wellbeing during stress.

Impact of loneliness on diurnal cortisol in youth.

Loneliness is associated with multiple forms of psychopathology in youth. However, we do not yet know how loneliness gets "under the skin" in ways that may impact the long-term health and development of early adolescents. In particular, loneliness may influence youths' patterns of diurnal cortisol, an index of hypothalamic-pituitary-adrenal (HPA) axis functioning and a central predictor of health across the lifespan. The current severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2, or COVID-19) pandemic represents a salient period in which to study the consequences of loneliness, as recent work has provided evidence that the physical-distancing measures put in place to contain the virus have resulted in greater loneliness, particularly among youth. Thus, the current study aimed to examine the prospective association between loneliness during the COVID-19 pandemic and diurnal cortisol in early adolescents. We found that greater loneliness was associated with higher levels of cortisol at waking and a blunted cortisol awakening response (CAR). These results held even when controlling for covariates that can influence diurnal trajectories of cortisol. Critically, this pattern of HPA-axis functioning increases risk for adverse mental and physical health outcomes across adolescence and into adulthood. This study is the first to examine the prospective association between loneliness and diurnal cortisol in early adolescence, and the first to identify mechanisms that contribute to biological markers of distress during the COVID-19 pandemic. Findings underscore the importance of developing and distributing strategies to mitigate feelings of loneliness among youth.