Anderson Travis, Vrshek-Schallhorn Suzanne, Wideman Laurie
United States Olympic and Paralympic Committee, Colorado Springs, CO, CO 80909, USA.
United States Coalition for the Prevention of Illness and Injury in Sport, Colorado Springs, CO, USA.
Eur J Appl Physiol. 2025 May;125(5):1475-1483. doi: 10.1007/s00421-024-05676-z. Epub 2025 Jan 3.
The cortisol awakening response (CAR) is a discrete component of the circadian cortisol profile. Evidence suggests that the CAR is a deviation from the pre-awakening increase in cortisol concentration, although this has yet to be replicated. Therefore, the purpose of this study was to replicate this finding and to investigate further the extent to which the CAR is distinct from the circadian profile. Twelve participants completed 2 overnight visits in a sleep laboratory. An intravenous catheter was used to sample blood every 15 min. Participants were allowed to sleep ad libitum beginning at 2030 h, and blood sampling continued throughout the night until 1 h post-awakening, generating a total of 802 serum samples. Selected serum samples were assayed for cortisol, and piece-wise linear mixed-effect models tested the extent to which the increase in cortisol concentrations post-awakening deviated from the rise in cortisol concentrations from various pre-awakening periods. Results demonstrated that the CAR only significantly deviates from the pre-awakening rise when the pre-awakening linear rise is considered 4 (β = 1.79, 95% CI = 0.49-3.09, p = 0.007) or 5 (β = 1.79, 95% CI = 0.49-3.09, p = 0.007) h before waking. When including a non-linear change in cortisol during the 4-h pre-awakening period, the deviation from the diurnal profile for the CAR was no longer significant (β = 0.96, 95% CI = - 0.74-2.66, p = 0.266). These results partly agree and replicate previous evidence for the CAR being superimposed on the diurnal profile but continue to extend our teleological understanding of the functional role of the CAR.
皮质醇觉醒反应（CAR）是昼夜皮质醇水平的一个独立组成部分。有证据表明，CAR是皮质醇浓度觉醒前升高的一种偏离，尽管这一发现尚未得到重复验证。因此，本研究的目的是重复这一发现，并进一步探究CAR与昼夜节律的不同程度。12名参与者在睡眠实验室完成了2次夜间访视。使用静脉导管每15分钟采集一次血液样本。参与者从20:30开始自由睡眠，整夜持续采血直至觉醒后1小时，共采集了802份血清样本。对选定的血清样本进行皮质醇检测，采用分段线性混合效应模型测试觉醒后皮质醇浓度的升高与觉醒前不同时间段皮质醇浓度升高的偏离程度。结果表明，只有当将觉醒前4小时（β = 1.79，95%置信区间 = 0.49 - 3.09，p = 0.007）或5小时（β = 1.79，95%置信区间 = 0.49 - 3.09，p = 0.007）的线性升高考虑在内时，CAR才显著偏离觉醒前的升高。当纳入觉醒前4小时内皮质醇的非线性变化时，CAR与昼夜节律的偏离不再显著（β = 0.96，95%置信区间 = - 0.74 - 2.66，p = 0.266）。这些结果部分认同并重复了之前关于CAR叠加在昼夜节律上的证据，但也继续扩展了我们对CAR功能作用的目的论理解。
