DISRUPTED SLEEP IN THE ELDERLY--CIRCADIAN ETIOLOGY

描述（改编自研究者摘要）：超过四分之一 的老年人抱怨他们在后半部分经常醒来 15%的人说他们无法在凌晨5点后入睡。 先前的研究结果表明，清晨醒来也发生在大多数健康 没有睡眠问题的老年人，没有抑郁症的人， 没有表现出任何与年龄相关的内在昼夜节律缩短的证据 期 由目前拨款资助的研究表明，这种与年龄有关的 在后半夜睡眠中断的增加， 可以解释为昼夜光重置的年龄相关变化 灵敏度 根据最近的分析，研究人员发现：1） 与年龄相关的昼夜节律相位间隔变窄， 睡眠的一部分可以保持巩固，导致明显的年龄相关 增加睡眠对昼夜节律相位失调的敏感性; 和2）与年龄相关的增加，在变异的夹带昼夜节律 相位 据推测，这些与年龄有关的昼夜节律变化可能 在高发病率的干扰中， 在老年人中观察到的睡眠和清晨觉醒。 这意味着对于老年人来说，实现和保持精确的（和 昼夜节律相位和睡眠时间之间的关系是 这对巩固睡眠至关重要。 调查人员对 光对人体节律的影响表明， 老年人的睡眠和内源性昼夜节律之间的联系 通过适当地定时曝光于新颖的曝光模式来实现 短暂间歇的亮光脉冲 提出了四个可检验的假说：（1）褪黑激素的相位， 温度节律和唤醒时间将发生在较早的时间为老年人 而不是在家里按照自己选择的睡眠时间表生活的年轻人; (II)在这些自选时间表的基线条件下， 老年人在夜间最后三分之一的清醒程度会更高 （三）每天四次短暂暴露于晚上明亮的光线， 足以建立和维持睡眠-觉醒周期的夹带 在最佳的昼夜节律阶段，导致最后一个月的觉醒减少， 第三天晚上，提高白天的警觉性;和（四）类似的 在早晨明亮的光线照射模式不会改善昼夜节律 相位失调

DESCRIPTION (adapted from investigator's abstract): More than one-quarter of older people complain that they wake up frequently during the latter part of the night, with 15 percent reporting that they cannot sleep past 5 AM. Prior results show that early morning awakening also occurs in most healthy older people who have no sleep complaint, who are not depressed and who do not exhibit any evidence of age-related shortening of intrinsic circadian period. Studies funded by the current grant suggest that this age-related increase in sleep interruptions during the latter part of the night cannot be explained by an age-related change in circadian photic resetting sensitivity. Based on recent analyses, the investigators have found: 1) an age-related narrowing of the circadian phase interval over which the latter part of sleep can remain consolidated, leading to a marked age-related increase in the susceptibility of sleep to misalignment of circadian phase; and 2) an age-related increase in the variability of entrained circadian phase. It is hypothesized that these age-related circadian changes may account for a substantial component of the high prevalence of disrupted sleep and early morning awakening observed among older people. This implies that in older people, achieving and maintaining a precise (and narrow) relationship between circadian phase and the timing of sleep is crucial to attain sleep consolidation. The investigators' findings on the effect of light on human rhythms suggest that the optimum phase relationship between sleep and endogenous circadian rhythms in older people can be achieved by appropriately timed exposure to a novel light exposure pattern of brief, intermittent bright light pulses. Four testable hypotheses are proposed: (I) the phase of the melatonin and temperature rhythms and wake-time will occur at an earlier hour for older than for young adults living on self-selected sleep-wake schedules at home; (II) under base-line conditions on those self-selected schedules, wakefulness in the final third of the night will be higher for older subjects; (III) four brief exposures to evening bright light each day will be sufficient to establish and maintain entrainment of the sleep-wake cycle at an optimal circadian phase, resulting in reduced wakefulness in the final third of the night and enhanced daytime alertness; and (IV) a similar pattern of bright light exposure in the morning will not improve circadian phase misalignment.