人类更爱晃着睡
摇晃婴儿入睡——既能让年轻人的哭声安静下来，又能让年轻父母保持清醒——在史前时代就已经司空见惯了。同样，有节奏的动作，比如火车上发出的无声的隆隆声，会诱使我们许多成年人立即进入睡眠状态——但这是为什么呢?
Two new studies published today in Current Biology suggest our brains are evolutionarily programmed to respond to rocking.The research shows in both humans and mice,rocking to sleep may have significant health benefits such as better quality of sleep and even improved long-term memory formation.
今天发表在《当代生物学》(Current Biology)杂志上的两项新研究表明，从进化的角度来看，我们的大脑天生就会对摇摆做出反应。研究表明，无论是对人类还是小鼠，摇晃着入睡都可能对健康有显著的好处，比如睡眠质量更好，甚至可以改善长期记忆的形成。
In the first study the authors used electroencephalography(EEG)recordings to analyze the brain responses of 18 young healthy adults who spent three nights in a sleep lab.The first night was intended to acclimate them to their new sleep environment;the second they spent in a slowly rocking bed;the third—one week later—in a stationary bed.
在第一项研究中，作者使用脑电图(EEG)记录分析了18名年轻健康成年人在睡眠实验室中度过三个晚上后的大脑反应。第一晚的目的是让他们适应新的睡眠环境;第二次他们在一张慢慢摇动的床上度过;第三个，一个星期后，躺在一张固定的床上。
Even in people who were already good sleepers,rocking shortened the time it took for subjects to fall asleep,and also to reach non-REM sleep,which correlates with improved sleep quality.The rockers also had fewer arousals and maintained deep sleep for a longer period of time.
即使是那些已经睡得很好的人，摇晃也缩短了他们入睡的时间，也缩短了他们进入非快速眼动睡眠的时间，这与睡眠质量的提高有关。此外，摇滚乐手的清醒时间也更短，深度睡眠的时间也更长。
Curious if rocking might have any influence on memory,study subjects were also tasked with memorizing 46 random word pairs.On both their rocking and non-rocking sleepovers they were then presented with the first word and asked to recall the second after a night’s sleep.A night of rocking improved their recall threefold.
出于对摇摆是否会影响记忆的好奇，研究对象还被要求记忆46个随机单词对。在摇床和非摇床两种情况下，研究人员都向他们展示了第一个单词，并要求他们在一夜睡眠后回忆第二个单词。一夜的摇动使他们的记忆力提高了三倍。
Finally rocking also was found to synchronize brain waves during non-REM sleep in the thalamocortical networks of the brain,a system known to be involved in both sleep and memory consolidation,the nocturnal process during which the brain processes and stores long-term memories.“What was surprising…is that we clearly showed that specific brain oscillations of non-REM sleep are synchronized and entrained by the rhythm of the bed motion,”says neuroscientist Laurence Bayer of the University of Geneva in Switzerland,who led the new study.Bayer likens the findings to our intuitive appreciation that a slowly rocking hammock can relax us and do wonders for our mood.“This is potentially a very promising avenue for future clinical research,”he notes.
最后，研究人员还发现，在非快速眼动睡眠期间，摇晃还能同步大脑丘脑皮质网络中的脑电波。这一系统被认为同时参与了睡眠和记忆巩固，也就是大脑处理和储存长期记忆的夜间过程。瑞士日内瓦大学的神经科学家劳伦斯·拜尔领导了这项新研究，他说:“令人惊讶的是，我们清楚地表明，非快速眼动睡眠的特定脑振荡是同步的，并被床上运动的节奏所控制。”拜耳将这一发现与我们直觉上的欣赏相比较，即一张慢慢摇动的吊床可以让我们放松，并对我们的情绪产生奇妙的影响。“这可能是未来临床研究的一个非常有前途的途径。”他指出。
Previous research—and millennia of relieved parents—support the fact rocking helps coax infants to sleep.And the new findings suggest the same is true in adults.Yet it was previously unknown whether or not the same is true in other species.
先前的研究——以及几千年来如释重负的父母们——支持这样一个事实:摇晃有助于哄婴儿入睡。新的发现表明，同样的道理也适用于成年人。然而，这在以前是未知的，是否同样的情况也存在于其他物种中。
The second study found that,at least in mice,it is.Like in the human study,rocking shortened the time it took the mice to fall asleep and increased the amount of sleep time,as measured by EEG recordings.Unlike humans,however,rocking did not seem to induce deeper sleep in the rodents.The authors suspected rocking might exert its influence on sleep by stimulating the vestibular system,the sensory organs in the inner ears of mammals that control our sense of balance and spatial orientation.Using a strain of mice with impaired vestibular function,they showed this is indeed the case.Specifically,half of the mice used in the study lacked“otoliths,”small calcium carbonate–based particles that bob around two compartments of the inner ear and allow mammals to perceive vertical and horizontal acceleration.Mice without these otolithic organs showed none of benefits of rocking during sleep.“Since immemorial times we’ve rocked our babies,and often ourselves,to sleep,”says lead author on the new paper,Konstantinos Kompotis,at the University of Lausanne,also in Switzerland.“Our study provides new insights into the neurophysiological mechanisms underlying this phenomenon.”
第二项研究发现，至少在老鼠身上是这样的。就像在人类研究中一样，通过脑电图记录，摇晃缩短了小鼠入睡的时间，增加了睡眠时间。然而，与人类不同的是，摇晃似乎并没有使啮齿动物进入深度睡眠。研究人员怀疑，摇晃可能通过刺激前庭神经系统对睡眠产生影响。前庭神经系统是哺乳动物内耳的感觉器官，控制着我们的平衡感和空间方向感。用一种前庭功能受损的老鼠做实验，他们发现事实确实如此。具体地说，研究中使用的老鼠中有一半缺乏“耳石”，这是一种以碳酸钙为基础的小颗粒，它在内耳的两个腔室之间来回摆动，使哺乳动物能够感知垂直和水平加速度。没有这些耳石器官的老鼠在睡眠时摇晃没有任何好处。“从远古时代起，我们就一直摇着我们的婴儿，经常是摇着自己入睡，”这篇新论文的第一作者、同样位于瑞士洛桑大学(University of Lausanne)的康斯坦蒂诺斯·孔波蒂斯(Konstantinos Kompotis)说。“我们的研究为这种现象背后的神经生理机制提供了新的见解。”
“These findings are critically important,”adds Bryce Mander,an assistant professor of psychiatry and human behavior at the University of California,Irvine,who was not involved in these studies.“Before these papers,both the mechanisms and the functional significance of the association between vestibular-related rocking and sleep were completely unknown.”He notes the new findings open the door to testing non-invasive behavioral interventions in those with impaired sleep and memory.
“这些发现非常重要，”加州大学欧文分校(University of California,Irvine)精神病学和人类行为助理教授布莱斯·曼德(Bryce Mander)补充道。他没有参与这些研究。在这些论文发表之前，前庭相关摇晃和睡眠之间联系的机制和功能意义都是完全未知的。他指出，这项新发现为测试睡眠和记忆受损人群的非侵入性行为干预措施打开了大门。
