RT Journal Article SR Electronic T1 Fatigue in industry. JF British Journal of Industrial Medicine JO Br J Ind Med FD BMJ Publishing Group Ltd SP 175 OP 186 DO 10.1136/oem.36.3.175 VO 36 IS 3 A1 Grandjean, E YR 1979 UL http://oem.bmj.com/content/36/3/175.abstract AB Physical fatigue is a painful phenomenon which is localised in overstressed muscles. Mental fatigue is a diffuse sensation of weariness; it is a functional state, one of several intermediate conditions between the two extremes of alarm and sleep. A neurophysiological model of fatigue, involving an activating and inhibitory system has been developed. Fatigue in industrial practice has clinical symptoms: psychic instability, fits of depression and increased liability to illness. Indicators of fatigue are work of performance, subjective feelings of fatigue, electroencephalography, flicker-fusion frequency and various psychomotor and mental tests. Several field studies do, to some extent, confirm the above-mentioned concept of fatigue.