Facer-Childs Elise R, Pake Katie, Lee Vivian Y, Lucas Samuel J E, Balanos George M
School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom.
School of Psychology, University of Birmingham, Birmingham, United Kingdom.
Front Physiol. 2019 Jul 10;10:901. doi: 10.3389/fphys.2019.00901. eCollection 2019.
The time of day when cardiovascular events are most likely to occur is thought to be aligned with the circadian rhythm of physiological variables. Chronotype has been shown to influence the time of day when cardiovascular events happen, with early chronotypes reported to be more susceptible in the morning and late chronotypes in the evening. However, no studies have investigated the influence of chronotype on physiological variables responsible for cardiovascular regulation in healthy individuals. 312 individuals completed the Munich ChronoType Questionnaire to assess chronotype. Twenty participants were randomly selected to continue into the main study. In a repeated-measures experiment, participants were tested between 08:00 and 10:00 h and again between 18:00 and 20:00 h. Measurements of mean arterial pressure, heart rate and vascular endothelial vasodilation via flow-mediated dilatation (FMD) were obtained at each session. Individual diurnal differences in mean arterial pressure and heart rate show no significant relationship with chronotype. Diurnal differences in FMD showed a significant correlation ( = 0.010), driven by a clear significant relationship in the evening and not the morning ( < 0.001). These preliminary data indicate that chronotype influences the diurnal variation of endothelial vasodilation measured using flow-mediated dilatation. Furthermore, we show that the influence of chronotype is much stronger in the evening, highlighting an increased susceptibility for later types. These findings are consistent with the diurnal rhythm in cardiovascular events and uncover potential mechanisms of local mediators that may underpin the influence of chronotype in the onset of these events.
人们认为心血管事件最可能发生的时间与生理变量的昼夜节律一致。昼夜节律类型已被证明会影响心血管事件发生的时间，据报道，早起型在早晨更易发生心血管事件，而晚睡型则在晚上更易发生。然而，尚无研究调查昼夜节律类型对健康个体中负责心血管调节的生理变量的影响。312名个体完成了慕尼黑昼夜节律类型问卷以评估昼夜节律类型。随机选择20名参与者继续进行主要研究。在一项重复测量实验中，参与者在08:00至10:00之间以及18:00至20:00之间接受测试。每次测试均测量平均动脉压、心率以及通过血流介导的血管舒张（FMD）测量血管内皮血管舒张功能。平均动脉压和心率的个体昼夜差异与昼夜节律类型无显著关系。FMD的昼夜差异显示出显著相关性（P = 0.010），这是由晚上而非早晨的明显显著关系驱动的（P < 0.001）。这些初步数据表明，昼夜节律类型会影响通过血流介导的血管舒张测量的内皮血管舒张的昼夜变化。此外，我们表明昼夜节律类型在晚上的影响要强得多，这突出了晚睡型个体更高的易感性。这些发现与心血管事件的昼夜节律一致，并揭示了局部介质的潜在机制，这些机制可能是昼夜节律类型在这些事件发生中产生影响的基础。
