Labyak S E, Lee T M, Goel N
School of Nursing, University of Michigan, Ann Arbor 48109-1109, USA.
Am J Physiol. 1997 Sep;273(3 Pt 2):R1058-66. doi: 10.1152/ajpregu.1997.273.3.R1058.
Interindividual variations in entrained human circadian rhythms and their relationship to differences in ease of adjustment to phase shifts have been well described. Humans classified as morning type (MT) display phase-advanced temperature minimum, onset of daily activity, and onset of sleep, whereas evening type (ET) individuals demonstrate the opposite pattern with a later phase angle of entrainment for these measures. We examined 15 variables of circadian activity and temperature for diurnal Octodon degus (n = 49; 28 male, 21 female), and noted similar chronotype variations as described for humans. Individuals with extreme MT and ET chronotypes were identified as those who differed from the entire population mean by one or more standard deviations. Compared with MTs (n = 5) and intermediate chronotypes (ITs, n = 34), ETs (n = 10) displayed a significant delay in the phase of temperature minimum, rise in temperature above the daily mean, and decline in activity and temperature below the daily mean, and had longer elevated activity and temperature durations and higher levels of mean daily activity and activity amplitude. MTs also displayed a significant phase advance in the morning temperature rise compared with ITs and ETs. This is the first description of variation in entrained circadian rhythms similar to that described for humans in both an outbred animal population and a diurnal rodent.
人类昼夜节律的个体差异及其与相位调整难易程度差异的关系已得到充分描述。被归类为早晨型（MT）的人表现出体温最低值提前、日常活动开始时间和睡眠开始时间提前，而晚上型（ET）个体则表现出相反的模式，这些指标的昼夜节律相位角更晚。我们研究了昼行性八齿鼠（Octodon degus）（n = 49；28只雄性，21只雌性）昼夜活动和体温的15个变量，并注意到与人类相似的昼夜节律类型变化。极端MT和ET昼夜节律类型的个体被确定为那些与总体均值相差一个或多个标准差的个体。与MT（n = 5）和中间昼夜节律类型（IT，n = 34）相比，ET（n = 10）在体温最低值相位、体温升至日均值以上、活动和体温降至日均值以下方面均有显著延迟，且活动和体温升高持续时间更长，日均活动水平和活动幅度更高。与IT和ET相比，MT在早晨体温上升方面也有显著的相位提前。这是首次在远交动物群体和昼行性啮齿动物中描述类似于人类的昼夜节律变化。
