NEUROENDOCRINE RESPONSES TO CAFFEINE IN THE WORK-ENVIRONMENT

The effect of caffeine on neuroendocrine stress responses in the workp lace was studied in 14 habitual coffee drinkers. Urinary catecholamine and cortisol levels were measured on 2 study days, in a 4-hour interv al from morning until noon, while participants performed their normal work-related activities. Caffeine (300 mg) or placebo was administered blind at the beginning of study intervals, after overnight caffeine a bstinence. Retrospective mood and symptom ratings were collected at th e end of each morning. Caffeine elevated urinary epinephrine levels du ring work by 37% but did not affect norepinephrine or cortisol levels. Subjective reports suggest that caffeine abstinence was associated wi th symptoms of caffeine withdrawal by the end of the morning. Effects included higher ratings of sleepiness, lethargy, and headache and a re duced desire to socialize. Results suggest caffeine may increase the a ctivity of the sympathetic adrenal-medullary system during everyday ac tivities in the work environment. This action may potentiate psychophy siological responses elicited by occupational stressors.