[Effect of vitamin B12 on sleep quality and performance of shift workers]

In modern industry shift systems are important for optimal economic utilization of high-grade working plants. The implementation of shift systems, however, goes along with far-reaching social and health responsibilities of these organizations. This study plores, to what extent the intake of vitamin B12 before the beginning of a day shift has a stabilizing influence on the quality of sleep and the subjective estimate of the performance of the volunteers. The study was performed on 10 healthy, male staff members of a Tyrolean industrial plant with a mean age of 35 years, who work in a 12/12-h shift system as doormen. In a single blind placebo-verum-order all volunteers received first of all placebo for 2 weeks, then vitamin B12 (Methylcobal, 3 mg) for 3 weeks, at the morning before the day shift. By means of modified sleep-onset- and wake-up- records we studied the morning and evening state, the estimates of sleep time / -quality as well as the subjective judgement of the performance. The statements about periods of rest and activity were compared with the objective data of the wrist actimetry. Vitamin B12--concentrations in the serum were prepared for baseline and verum trials for each individual. In the whole group there were no significant differences in sleep-onset and wake-up ratings, nor in the subjective judgement of performance between placebo and verum. There were no significant particularities with respect to the weekdays or the time of day of activity. There was a tendency for the total sleep time in the verum trial to be shorter. The mean estimate of sleep quality under verum in significantly higher than under placebo in all volunteers.