Ontogeny of Rem Sleep, Nrem Sleep and Awake State in the Human Fetus in Utero

在过去的3年中，我们继续对人类胎儿在子宫内的行为模式的个体发生进行研究，使用实时超声观察，与脑功能的发育有关。在妊娠16周左右可观察到胎仔眼球运动，零星发生。在妊娠24 - 25周以后，发现眼球运动逐渐巩固，从而导致眼球运动（REM）和非眼球运动（NREM）时期的形成。最迟在妊娠37 - 38周时，REM和NREM期显示出几乎一致的持续时间的交替变化：分别为24（平均值）和22分钟。当试图通过分段回归分析个体眼球运动的持续时间作为参数时，在妊娠33周或更长时间的胎儿中，观察到临界给定持续时间点为0.6 - 0.7秒，具有统计学显著性。这一发现表明，有两种不同类型的眼球运动：快速和缓慢的眼球运动，从而揭示了快速眼动睡眠状态在子宫内的存在。在REM睡眠期间观察到在300和525毫秒之间的广泛间隔内发生的随机张口运动，并且与妊娠进展无关，而每300至600毫秒的定期张口仅在妊娠35周后的NREM期发生。这为胎儿存在NREM睡眠状态提供了证据.从瞳孔散大/缩瞳与REM/NREM期关系的研究中可以看出，孕36-40周胎儿中约有5%的检查期出现在REM期，这是一个瞳孔散大的特殊时期。因此，这一发现有力地表明了清醒状态的萌芽始于宫内生活。我们相信我们的结果将朝着人类胎儿行为学迈出一步。

For the past 3 years, we have continued to make studies on ontogeny of behavioral patterns in the human fetus in utero, observed using a real-time ultrasound, in relation to the development of brain function.Consequently, the following findings were obtained :1. Fetal eye movement became observable at around 16 weeks of gestation with sporadic onset of occurrence. At 24-25 weeks of gestation onwards, the eye movement was found to gradually consolidate, thereby leading to formation of eye-movement (REM) and non eye-movement (NREM) periods. At the latest by 37-38 weeks of gestation, REM and NREM periods revealed an alternative change with almost uniform duration : 24 (mean value) and 22 minutes, respectively.2. When attempting to analyze the duration of the individual eye movement as a parameter by means of piecewise regression, the critical given duration point was noted, with statistical significance, at 0.6-0.7 second in the fetuses at 33 weeks of gestation or more. This finding demonstrates that there are two different types of eye movement : rapid and slow eye movements, thereby revealing the in utero existence of REM sleep state.3. Random mouthing movements occurring at a wide range of interval between 300 and 525 milliseconds were observed during REM sleep and were unrelated to advance in gestation, while regular mouthing every 300 to 600 milliseconds concurred only with NREM period at 35 weeks of gestation thereafter. This provides the evidence that there exists NREM sleep state in the human fetus.4. From study on relation between mydriasis/miosis and REM/NREM periods, it was evident that about 5% of examination period in the fetuses at 36-40 weeks of gestation was observed to show the special period with mydriasis occurring during REM period. Therefore, this finding strongly suggests a sprout of awake state beginning during intrauterine life.We believe our results will take a step toward human fetal ethology.