Abstract
The cortisol awakening response (CAR), a rapid cortisol rise in the morning after awakening, has been proposed to provide energy to cope with daily demands and suggested to be associated with brain functions. Electroencephalogram (EEG) asymmetry studies have implicated asymmetric cortical activation, especially in frontal cortex, in approach-withdrawal motivation. In this study, we examined the relationship between the CAR and lateralized cortical activity under rest in 55 university male students. Saliva samples were collected at 0, 15, 30 and 60 min after awakening on the two consecutive workdays. The lateralized cortical activity at frontocentral sites was examined by alpha asymmetry score. The results showed that a higher CAR was positively associated with alpha asymmetry score, which indicated that the higher CAR is linked with more left-sided cortical activity at frontocentral sites under resting state. This association still existed even after controlling psychological and sleep quality variables. These results suggested that appropriately mobilizing energy resource storage after awakening revealed as CAR might be associated with goal-directed approach tendencies before any eventual stressful situation, characteristic of more left than right resting-state frontocentral cortical activity.
Highlights
The activity of the hypothalamus-pituitary-adrenal (HPA) axis has a marked diurnal circadian rhythm, which is characterized by the levels of its end-product cortisol in human
Cortisol level There was a clear pattern of dynamic secretion of morning cortisol: the cortisol levels increased from awakening point (14.315, standard errors (SE): 0.968 nmol/L) to peak at 15–30 min after awakening (16.706 ± 1.016 nmol/L and 16.915 ± 0.876 nmol/L, respectively), and declined at 60 min after awakening (12.889 ± 0.583 nmol/L)
Association between the cortisol level and EEG activity The Pearson correlation analysis revealed that AUCg was marginally associated with alpha asymmetry score at frontocentral sites (r = 0.250, p = 0.065)
Summary
The activity of the hypothalamus-pituitary-adrenal (HPA) axis has a marked diurnal circadian rhythm, which is characterized by the levels of its end-product cortisol in human. A recent study showed that children from low socioeconomic status had decreased CAR, which was mediated by parental and child anxiety (Zhu et al, 2019). This bidirectional association might suggest the role of coping style in the CAR, that is, the experience of general and work stress elicits an active engagement with the environment and the higher CAR, while prolonged stress and burnout-related factors elicit conservation/ withdrawal response with the environment and the lower CAR (Chida & Steptoe, 2009)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
