Li Peng, Morris Christopher J, Patxot Melissa, Yugay Tatiana, Mistretta Joseph, Purvis Taylor E, Scheer Frank A J L, Hu Kun
Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Boston, MA.
Division of Sleep Medicine, Harvard Medical School, Boston, MA.
Sleep. 2017 Jul 1;40(7). doi: 10.1093/sleep/zsx092.
Healthy physiology is characterized by fractal regulation (FR) that generates similar structures in the fluctuations of physiological outputs at different time scales. Perturbed FR is associated with aging and age-related pathological conditions. Shift work, involving repeated and chronic exposure to misaligned environmental and behavioral cycles, disrupts circadian coordination. We tested whether night shifts perturb FR in motor activity and whether night shifts affect FR in chronic shift workers and non-shift workers differently.
We studied 13 chronic shift workers and 14 non-shift workers as controls using both field and in-laboratory experiments. In the in-laboratory study, simulated night shifts were used to induce a misalignment between the endogenous circadian pacemaker and the sleep-wake cycles (ie, circadian misalignment) while environmental conditions and food intake were controlled.
In the field study, we found that FR was robust in controls but broke down in shift workers during night shifts, leading to more random activity fluctuations as observed in patients with dementia. The night shift effect was present even 2 days after ending night shifts. The in-laboratory study confirmed that night shifts perturbed FR in chronic shift workers and showed that FR in controls was more resilience to the circadian misalignment. Moreover, FR during real and simulated night shifts was more perturbed in those who started shift work at older ages.
Chronic shift work causes night shift intolerance, which is probably linked to the degraded plasticity of the circadian control system.
健康生理学的特征是分形调节（FR），它在不同时间尺度的生理输出波动中产生相似的结构。FR紊乱与衰老及年龄相关的病理状况有关。轮班工作涉及反复和长期暴露于失调的环境和行为周期，会破坏昼夜节律协调。我们测试了夜班是否会扰乱运动活动中的FR，以及夜班对长期轮班工作者和非轮班工作者的FR影响是否不同。
我们以13名长期轮班工作者为研究对象，并选取14名非轮班工作者作为对照，进行了实地和实验室实验。在实验室研究中，在控制环境条件和食物摄入的同时，利用模拟夜班来诱导内源性昼夜节律起搏器与睡眠-觉醒周期之间的失调（即昼夜节律失调）。
在实地研究中，我们发现对照组的FR很稳定，但轮班工作者在夜班期间的FR遭到破坏，导致活动波动更加随机，这与痴呆患者的情况相似。即使在夜班结束两天后，夜班的影响依然存在。实验室研究证实夜班扰乱了长期轮班工作者的FR，并表明对照组的FR对昼夜节律失调更具恢复力。此外，在实际和模拟夜班期间，开始轮班工作时年龄较大者的FR受到的干扰更大。
长期轮班工作会导致夜班不耐受，这可能与昼夜节律控制系统可塑性下降有关。
