6-Sulphatoxymelatonin: Effect of 12-Hour Shift Work and Personality Characteristics

Katja K. Vangelova and Bistra M. Tzenova

Department of Physiology and Psychology of Work, National Center of Hygiene, Sofia

Corresponding author: K. Vangelova

National Center of Hygiene

D. Nestorov 15,

1431 Sofia, Bulgaria

FAX: (+359) 2 95 81 277

CEJOEM 1997, 3:132-142

Key words:
6-sulphatoximelatonin, shift work, negative affectivity, motivation, mental health

Abbreviations:
aMT6s – 6-sulphatoxymelatonin
IgA – Immunoglobulin A
NKC – natural killer cells

Abstract:
The circadian biological rhythms and their adjustment during night shift period are known to be related to some individual characteristics. The pineal gland hormone – melatonin, synchronizer of the “body clock”, is reliably measured by the excretion of 6-sulphatoxymelatonin (aMT6s).The aim of the present study was to assess the aMT6s excretion and its possible connection to personality under extended shifts. Twenty-one thermoelectric power operators working 2×12-h shifts were investigated. Urine samples were collected at 4-hour intervals during the day and night shifts. The aMT6s was determined by using the RIA kit. Data on psychosomatic status, affectivity, subjective time pressure and motivation were obtained.
The time-on-shift variations of the aMT6s excretion exhibited the typical diurnal pattern during the day and night shifts. The high early day excretion was associated with the total day excretion as well as with the night peak and the total night shift excretion. Low melatonin excretion was related with the sense of time pressure and work motivation.

Received: 02 January 1996 Accepted: 19 March 1997 Posted: 29 November 1998
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