Gordijn M C, Beersma D G, Korte H J, van den Hoofdakker R H
Department of Biological Psychiatry, University Clinic, Groningen, The Netherlands.
J Sleep Res. 1999 Sep;8(3):163-74. doi: 10.1046/j.1365-2869.1999.00156.x.
The purpose of the study was to induce in two different ways, a phase-angle difference between the circadian pacemaker and the imposed sleep-wake cycle in humans, we intended to: (i) shift the circadian pacemaker by exposure to bright light and keep the timing of the sleep-wake cycle fixed; and (ii) keep the timing of the circadian pacemaker fixed by a constant light-dark cycle and displace sleep. We monitored dim light melatonin onset (DLMO), core body temperature and sleep. DLMO was delayed significantly after 3 days of a 3-h delayed sleep-phase when compared with 3 days of sleep at a normal or 3-h advanced sleep-phase. The shifts in DLMO were not accompanied by shifts in body temperature, changes in waking-up time or by a change in the duration of the first rapid eye movement (REM) sleep episode. Three days of light exposure in the morning or evening resulted in shifts in DLMO of similar magnitude, but this was accompanied by shifts in the rhythm of body temperature, changes in waking-up time and in the duration of the first REM sleep episode. We conclude that the changes observed after light exposure reflect shifts in the circadian pacemaker. In contrast, we propose that the changes observed in DLMO after sleep displacement are not mediated by the circadian pacemaker. These results raise some doubts about the reliability of DLMO as a marker of circadian phase in cases of sleep disturbances. Finally, we initiate a search for changes in sleep that might be responsible for the unexpected effects on DLMO.
该研究的目的是以两种不同方式诱导人体昼夜节律起搏器与设定的睡眠-觉醒周期之间产生相位角差异，我们打算：（i）通过暴露于强光来使昼夜节律起搏器发生偏移，并保持睡眠-觉醒周期的时间固定；以及（ii）通过恒定的明暗周期使昼夜节律起搏器的时间固定，并改变睡眠。我们监测了暗光褪黑素起始（DLMO）、核心体温和睡眠情况。与正常睡眠阶段或提前3小时睡眠阶段的3天相比，在延迟3小时睡眠阶段的3天后，DLMO显著延迟。DLMO的偏移并未伴随着体温的偏移、起床时间的变化或首次快速眼动（REM）睡眠时段时长的改变。早晨或晚上3天的光照暴露导致DLMO产生相似幅度的偏移，但这伴随着体温节律的偏移、起床时间的变化以及首次REM睡眠时段时长的改变。我们得出结论，光照暴露后观察到的变化反映了昼夜节律起搏器的偏移。相比之下，我们提出睡眠位移后在DLMO中观察到的变化并非由昼夜节律起搏器介导。这些结果对DLMO在睡眠障碍情况下作为昼夜节律相位标志物的可靠性提出了一些质疑。最后，我们开始寻找可能导致对DLMO产生意外影响的睡眠变化。
