Central Queensland University, Health, Medical and Applied Sciences, Adelaide, SA, Australia.
Central Queensland University, Health, Medical and Applied Sciences, Adelaide, SA, Australia.
Psychoneuroendocrinology. 2019 Nov;109:104406. doi: 10.1016/j.psyneuen.2019.104406. Epub 2019 Aug 17.
This study had two specific objectives, 1) to investigate the impact of being on-call on overnight heart rate variability during sleep and; 2) to examine whether being on-call overnight impacted next-day salivary cortisol concentrations.
Data are reported from three within-subject laboratory studies (n = 24 in each study) that assessed varying on-call conditions. Healthy male participants (n = 72 total) completed a four-night laboratory protocol, comprising an adaptation night, a control night, and two counterbalanced on-call nights with varying on-call conditions. These on-call conditions were designed to determine the impact of, Study 1: the likelihood of receiving a call (definitely, maybe), Study 2: task stress (high-stress, low-stress), and Study 3: chance of missing the alarm (high-chance, low-chance), on measures of physiological stress. Overnight heart rate variability (HRV) (during sleep) was measured using two-lead electrocardiography, and time- and frequency-domain variables were analysed. Saliva samples were collected at 15-min time intervals from 0700-0800 h to determine cortisol awakening response outcomes and at four daily time points (0930 h, 1230 h, 1430 h, and 1730 h) to assess diurnal cortisol profiles.
There were few differences in HRV measures during sleep across all three studies. The only exception was in Study 1 where the standard deviation of the time interval between consecutive heartbeats and the root mean square of consecutive differences between heartbeats were lower across all sleep stages in the definitely condition, when compared to control. Across all three studies, being on-call overnight also had little impact on next-day cortisol awakening response (CAR), with the exception of Study 2 where the 1) CAR area under the curve with respect to increase was blunted in the high-stress condition, compared to the control and low-stress conditions and, 2) CAR reactivity was higher in low-stress condition, compared with the high-stress condition. In Study 1, diurnal cortisol area under the curve with respect to ground was lower in the on-call conditions (definitely and maybe) when compared to control. There were no differences in diurnal cortisol measures in Study 3.
This is the first study to investigate how different aspects of being on-call affect physiological stress responses. Overall, relatively little differences in measures of overnight heart rate variability and next-day cortisol response were recorded in all three studies. Further research utilising real on-call work tasks, not just on-call expectations (as in the current study) will help determine the impact of on-call work on the physiological stress response.
本研究有两个具体目标，1）调查夜间值班对睡眠期间夜间心率变异性的影响；2）检验夜间值班是否会影响次日唾液皮质醇浓度。
本研究报告了三项基于个体的实验室研究的数据（每项研究均有 24 名参与者），这些研究评估了不同的值班条件。健康男性参与者（总计 72 名）完成了为期四晚的实验室方案，包括适应期、对照期和两个值班条件不同的对照期。这些值班条件旨在确定 Study 1 中：接到电话的可能性（肯定、可能），Study 2 中：任务压力（高压力、低压力），以及 Study 3 中：错过闹钟的可能性（高概率、低概率）对生理压力测量的影响。使用双导联心电图测量夜间心率变异性（HRV）（睡眠期间），并分析时域和频域变量。从 0700-0800 点每隔 15 分钟采集一次唾液样本，以确定皮质醇觉醒反应结果，并在四个日常时间点（0930 点、1230 点、1430 点和 1730 点）评估日间皮质醇谱。
在所有三项研究中，睡眠期间的 HRV 测量值差异不大。唯一的例外是在 Study 1 中，在肯定条件下，与对照相比，所有睡眠阶段的连续心跳时间间隔的标准差和连续心跳之间的均方根差都较低。在所有三项研究中，夜间值班对次日皮质醇觉醒反应（CAR）的影响也很小，只有在 Study 2 中，1）高压力条件下的 CAR 曲线下面积与增加的关系变钝，与对照和低压力条件相比，以及 2）低压力条件下的 CAR 反应性更高，与高压力条件相比。在 Study 1 中，与对照相比，值班条件（肯定和可能）下的日间皮质醇曲线下面积与基础值较低。在 Study 3 中，日间皮质醇测量值无差异。
这是第一项研究不同方面的值班如何影响生理应激反应的研究。总体而言，在所有三项研究中，夜间心率变异性和次日皮质醇反应的测量值差异相对较小。利用真实的值班工作任务（而不是当前研究中的值班期望）进行进一步研究将有助于确定值班工作对生理应激反应的影响。
