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Twenty-four-hour prolactin profiles in night workers
K Spiegel1, L Weibel, C Gronfier
1Laboratoire de Physiologie et de Psychologie Environnementales, Strasbourg, France.
Chronobiology International
|October 1, 1996
Summary
This study investigated prolactin (PRL) secretion rhythms in night workers and found a persistent nocturnal PRL peak, suggesting an endogenous circadian rhythm component independent of sleep schedule. This challenges assumptions about PRL regulation in shift workers.
Area of Science:
- Chronobiology
- Endocrinology
- Sleep Science
Background:
- Circadian rhythmicity influences prolactin (PRL) secretion.
- The role of endogenous clocks in PRL temporal organization requires further investigation, especially in non-standard sleep schedules.
Purpose of the Study:
- To determine if PRL rhythm adapts to night work rest-activity schedules.
- To assess evidence for an endogenous, clock-driven component in PRL secretion patterns.
Main Methods:
- Plasma PRL, body temperature, and melatonin levels were measured at 10-min intervals in eight night workers and ten control subjects.
- Control subjects underwent an abrupt sleep shift to daytime.
Main Results:
- Twenty-four-hour PRL profiles showed no significant difference between night workers and controls after a sleep shift.
- A consistent nocturnal PRL peak was observed in both groups, irrespective of sleep timing.
- Melatonin phase shifts varied in night workers, while body temperature showed more consistent adaptation to the altered schedule.
Conclusions:
- The persistence of a nocturnal PRL peak in night workers suggests an endogenous circadian rhythm component.
- PRL secretion rhythm may not fully adapt to altered rest-activity schedules, indicating a robust internal clock influence.
- The significance of this persistent nocturnal PRL peak warrants further investigation.