Psychophysiological stress effects from the combination of night-shift work and noise

The influence of night-shift work and noise on arousal and stress reactions have, to date, been investigated separately. The aim of this study was to compare their psychophysiological effects in combination. Twenty-four male student subjects continuously performed ten hours of visual display tasks per 24 h under highly controlled conditions for either five consecutive day or night shifts, followed by two days of rest. Each group worked in conditions of simulated traffic noise, at either 80 or 50 dB(A). Urinary catecholamines, electrodermal activity, heart rate, and ratings of mood and physical symptoms were recorded continuously or at specified intervals. Catecholamine excretion rates, autonomic reactions, reaction times, and ratings of subjective alertness showed changes typical for night-shift work. No main effects of noise were found, but significant interactions between the two experimental factors reflected differential actions of noise dependent on the type of shift. The results favor a multiple-arousal concept. Night-shift work primarily influences general arousal, while noise affects both general and goal-directed arousal, dependent on the presentation during day or night shift.