Purpose: It has been shown that shift work constitutes a great health hazard, particularly when chronodisruption is involved. Anesthetists are used to working for a certain number of 24-h shifts every month. The work-related lack of sleep in combination with light exposure is suspected to alter melatonin courses. The main aim of the present study was to analyze circadian melatonin profiles before, during, and after a 24-h shift in anesthetists and medical students (controls). Furthermore, we evaluated possible differences in melatonin profiles between the groups. Interactions between specific parameters were calculated.
Methods: Over three consecutive days, including a 24-h shift, urine samples were collected daily at five time points. 6-Sulfateoxymelatonin (aMT6-s) courses were assayed using a commercially available competitive immunoassay kit.
Results: Ten anesthetists aged between 29 and 35 years and ten medical students aged between 25 and 31 years were included in the study. aMT6-s fluctuated between nocturnal values of (mean [range]) 2.2 (1.4; 3.0) pg/ml and morning values of 25.5 (12.1; 39.0) pg/ml. A marked circadian rhythm of aMT6-s courses was observed in both groups. Analyses of variance showed an effect of the factor "time" on aMT6-s concentrations but not of the factor "anesthetists versus students". Correlations between aMT6-s, the amount of sleep, and the time since the last extended duration shift could be found.
Conclusions: The results show no evidence for a single 24-h shift having a great impact on circadian disruption as evidenced by a similar melatonin profile for both groups over the study phase.