Temporal factors in sympatho-adrenomedullary activity following acute behavioral activation.

Abstract Sixteen healthy male subjects performed a complex choice-reaction task under time pressure. Adrenaline and noradrenaline excretion, heart rate, and subjective reactions were measured before, during, and after the work period and at corresponding points in time in a control session without work. Mean adrenaline excretion, heart rate, and subjective arousal increased significantly during work and returned to baseline levels within 1–2 hr after the end of work. There were large inter-individual differences in the rate at which adrenaline output decreased. When subjects whose adrenaline output decreased rapidly were compared with those whose adrenaline output decreased slowly, it was found that ‘rapid decreasers’ had higher baseline levels of adrenaline, performed better on the choice-reaction task, and had lower scores in neuroticism. The significance of temporal factors in adrenaline-mediated adjustment to environmental stressors is discussed.