Cortisol and catecholamines changes as functions of time-of-day and self-reported mood

Six male graduate students, unrestricted in their lifestyle, collected their own urine over a seven-day period: it was analysed for cortisol, noradrenaline, adrenaline and dopamine. At each urination subjects self-assessed their mood. On two separate days, blood samples were collected at 4-hourly intervals for plasma cortisol assay. Mean plasma cortisol levels showed the expected circadian variation, but two subjects had divergent patterns. Mean urine cortisol accumulation also showed circadian variation with a 2–4 hour lag behind plasma values. Mean urine catecholamine levels showed both time of day and considerable individual variation. A statistical procedure, involving comparison of two models, was developed to determine differences between subjects' excretion patterns. An underlying common pattern of cortisol and catecholamines excretion was found. Regression of hormone levels against self-assessed mood changes revealed correlations of (1) adrenaline accumulation with physical fatigue, (2) cortisol with alertness and (3) ratios of adrenaline, noradrenaline and dopamine with tenseness and irritability.