Pollak C P, Tryon W W, Nagaraja H, Dzwonczyk R
Department of Neurology, The Ohio State University, Columbus, 43210, USA.
Sleep. 2001 Dec 15;24(8):957-65. doi: 10.1093/sleep/24.8.957.
Because sleep and wakefulness differ from each other by the amount of body movement, it has been claimed that the two states can be accurately distinguished by wrist actigraphy. Our objective was to test this claim in lengthy polysomnographic (psg) and actigraphic (acf) samples that included night and day components.
Fourteen healthy young (21-35 years) and old (70-72 years) men and women lived in a laboratory without temporal cues for 7 days. Each subject continuously wore sleep-recording electrodes as well as 2 wrist-movement recorders. Act measurements were converted to predictions of sleep and wakefulness by simple-threshold and multiple-regression methods. Psg served as the gold standard for calculation of predictive values (PV, the probability that an act prediction is correct by psg criteria).
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The 7-day act recordings showed clear circadian cycles of high and low activity that respectively corresponded to subjective days, when subjects were wakeful, and subjective nights when they slept. Lower act levels corresponded to deeper states of psg sleep. Logistic regression on a 20-minute moving average of act gave the highest overall PV's. Nevertheless, the mean PV for sleep (PVS) was only 62.2% in complete, day + night samples. PVS was 86.6% in night samples. Act successfully predicted wakefulness during subjective nights (PVW = 89.6) and accurately measured circadian period length and the extent of sleep-wake consolidation, but it overestimated sleep rate and sleep efficiency. Act systematically decreased before sleep onset and increased before awakening, but reliable transitions among joint psg/act states (the Markov-1 property) were not demonstrated.
Low PV's and overestimation of sleep currently disqualify actigraphy as an accurate sleep-wake indicator. Actigraphy may, however, by useful for measuring circadian period and sleep-wake consolidation and has face validity as a measure of rest/activity.
由于睡眠和清醒在身体活动量上存在差异，有人声称可以通过手腕活动记录仪准确区分这两种状态。我们的目的是在包含昼夜成分的长时间多导睡眠图（PSG）和活动记录仪（ACF）样本中验证这一说法。
14名健康的年轻（21 - 35岁）和老年（70 - 72岁）男性和女性在无时间线索的实验室中生活7天。每位受试者持续佩戴睡眠记录电极以及2个手腕活动记录仪。通过简单阈值法和多元回归法将活动测量值转换为睡眠和清醒的预测值。PSG作为计算预测值（PV，即根据PSG标准活动预测正确的概率）的金标准。
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7天的活动记录显示出明显的昼夜高活动和低活动周期，分别对应于主观白天（受试者清醒时）和主观夜晚（受试者睡眠时）。较低的活动水平对应于PSG睡眠的较深状态。对活动的20分钟移动平均值进行逻辑回归得出的总体PV最高。然而，在完整的昼夜样本中，睡眠的平均PV（PVS）仅为62.2%。夜间样本中的PVS为86.6%。活动记录仪成功预测了主观夜间的清醒状态（PVW = 89.6），并准确测量了昼夜周期长度和睡眠 - 清醒巩固程度，但高估了睡眠率和睡眠效率。活动在睡眠开始前系统性下降，在醒来前增加，但未证明PSG/活动联合状态之间的可靠转换（马尔可夫 - 1属性）。
目前，低PV值和对睡眠的高估使活动记录仪不能作为准确的睡眠 - 清醒指标。然而，活动记录仪可能有助于测量昼夜周期和睡眠 - 清醒巩固，并且作为休息/活动的一种测量方法具有表面效度。
