Murphy P J, Rogers N L, Campbell S S
Laboratory of Human Chronobiology, Department of Psychiatry, Weill Medical College of Cornell University, White Plains, NY 10605, USA.
J Sleep Res. 2000 Mar;9(1):27-34. doi: 10.1046/j.1365-2869.2000.00185.x.
The stage from which the spontaneous ending of sleep occurred was investigated in 138 sleep episodes obtained from 14 younger (19-28 years) and 11 older (60-82 years) individuals. The possible influences of circadian phase and quality of the preceding sleep period, as well as the impact of aging on characteristics of sleep termination were examined. Under experimental conditions in which subjects were isolated from time cues, and behavioral options to sleep were limited, no age-associated differences in the duration of sleep periods, or in the number or duration of REM episodes were observed. Despite similar percentages of NREM (stages 2-4) and REM sleep across age groups, younger subjects awakened preferentially from REM while older subjects did not. Of the sleep episodes obtained from older subjects, those with sleep efficiencies higher than the median were more likely to terminate from REM than those with lower sleep efficiencies. For all subjects, the REM episodes from which sleep termination occurred were truncated relative to those that did not end the sleep period. In addition, nonterminating REM episodes that were interrupted by a stage shift were most often interrupted by brief arousals to stage 0. Such arousals within nonterminating REM episodes occurred, on average, after a similar duration as the terminating point of sleep-ending REM episodes. The results from this study demonstrate that there are age-related differences in the sleep stage from which spontaneous awakenings occur, and that these differences may be due in part to the quality of the sleep period preceding termination. Findings regarding the characteristics of both terminating and nonterminating REM episodes are consistent with the notion that the neural and biochemical context of REM sleep may facilitate a smooth transition to wakefulness. It is speculated that age-associated changes in sleep continuity may render unnecessary the putative role of REM sleep in providing a 'gate' to wakefulness.
对从14名较年轻（19 - 28岁）和11名较年长（60 - 82岁）个体获取的138个睡眠片段进行了研究，以确定睡眠自然结束时所处的阶段。研究考察了昼夜节律阶段和前一晚睡眠质量的可能影响，以及衰老对睡眠终止特征的影响。在将受试者与时间线索隔离且睡眠行为选择受限的实验条件下，未观察到不同年龄组在睡眠时间长度、快速眼动（REM）睡眠片段数量或时长方面存在与年龄相关的差异。尽管各年龄组的非快速眼动（NREM，2 - 4期）睡眠和REM睡眠百分比相似，但较年轻受试者优先从REM睡眠中醒来，而较年长受试者则不然。在从较年长受试者获取的睡眠片段中，睡眠效率高于中位数的片段比睡眠效率较低的片段更有可能从REM睡眠中终止。对于所有受试者，导致睡眠终止的REM睡眠片段相对于未结束睡眠期的片段而言被截断。此外，被阶段转换打断的未终止REM睡眠片段最常被短暂唤醒至0期打断。在未终止的REM睡眠片段中的此类唤醒平均发生在与导致睡眠结束的REM睡眠片段的终止点相似的时长之后。这项研究的结果表明，自然觉醒发生时的睡眠阶段存在与年龄相关的差异，并且这些差异可能部分归因于终止前睡眠期的质量。关于终止和未终止REM睡眠片段特征的研究结果与REM睡眠的神经和生化环境可能有助于向清醒平稳过渡这一观点一致。据推测，与年龄相关的睡眠连续性变化可能使REM睡眠在提供“通向清醒的大门”这一假定作用变得不再必要。
