Department of Public Health and Clinical Medicine, Umeå University, SE-901 85 Umeå, Sweden.
Psychoneuroendocrinology. 2012 Jun;37(6):789-800. doi: 10.1016/j.psyneuen.2011.09.011. Epub 2011 Oct 11.
Temporary employment is an increasingly common contract type, which has not been investigated in a psychoneuroendocrinological context despite previous observations of associations between adverse work and employment conditions and hypothalamic-pituitary-adrenal (HPA) axis dysregulations. The present study aims to examine whether the 12-year accumulation of temporary employment is related to circadian cortisol levels, and if any association is independent of current employment conditions. Participants were drawn from the prospective Northern Swedish Cohort (n=791, 74% of the original cohort). At age 43 years, retrospective reports of employments over the last 12 years and of current social conditions were collected by questionnaire, and one-day salivary cortisol profile was measured (at awakening, +15 min post-awakening, pre-lunch, bedtime). Results indicated a gradually higher magnitude of the cortisol awakening response (CAR) in subjects with no (0 months in temporary employment; mean CAR=34%), moderate (1-25 months in temporary employment; mean CAR=41%) and heavy (>25 months in temporary employment; mean CAR=51%) exposure (p=.020), remaining after adjustment for potential confounders and for current employment conditions (p=.028). The higher CAR was explained by lower awakening rather than higher post-awakening cortisol levels. Cortisol levels at all times of the day except post-awakening displayed tendencies to negative relations to temporary employment; as indicated by a lower Area Under of Curve (regression coefficient=5.0%, p=.038 after adjustment). This study thus suggests that the long-term exposure to temporary employment might confer HPA dysregulations in the form of increased dynamics of the CAR and circadian suppression.
临时工是一种越来越常见的合同类型，尽管先前观察到不利的工作和就业条件与下丘脑-垂体-肾上腺（HPA）轴失调之间存在关联，但在心理神经内分泌学方面尚未对此进行研究。本研究旨在检验过去 12 年临时工的累计工作时长是否与皮质醇昼夜节律水平相关，以及任何关联是否独立于当前的就业条件。参与者来自前瞻性的瑞典北部队列研究（n=791，占原始队列的 74%）。在 43 岁时，通过问卷调查收集了过去 12 年的就业情况和当前社会状况的回溯报告，并测量了一天的唾液皮质醇水平（觉醒时、觉醒后 15 分钟、午餐前、睡前）。结果表明，在没有（临时工工作时长为 0 个月；平均 CAR=34%）、中度（临时工工作时长为 1-25 个月；平均 CAR=41%）和高度（临时工工作时长>25 个月；平均 CAR=51%）暴露的受试者中，皮质醇觉醒反应（CAR）的幅度逐渐增加（p=.020），在调整了潜在混杂因素和当前就业条件后仍然如此（p=.028）。较高的 CAR 可归因于较低的觉醒水平而非较高的觉醒后皮质醇水平。除了觉醒后，一天中所有时间的皮质醇水平都与临时工工作时长呈负相关趋势；全天的曲线下面积（AUC）降低（调整后回归系数=5.0%，p=.038）。因此，本研究表明，长期临时工工作可能会导致 HPA 失调，表现为 CAR 动力学增加和昼夜节律抑制。
