新鲜人 发表于 2020-10-1 13:31:06

正常睡眠的分期和结构

本帖最后由 新鲜人 于 2020-10-1 17:00 编辑


  https://pic1.zhimg.com/ed63e5b23_xs.jpg?source=172ae18b

  Jerry zhao  文艺青年

  引言 — 睡眠是一种反应、运动活动和代谢减低的状态,可被快速逆转。这是一种可在所有动物中以某种形式观察到的现象;这种普遍性提示睡眠行为很可能具有一定进化意义。人类一生中约1/3的时间(每晚约8个小时)在睡眠。然而,对睡眠的目的了解甚少,目前存在多种理论。这些理论包括恢复理论、节约能量理论和记忆巩固理论。


  多导睡眠图是实验室评估睡眠的主要工具,可用于临床和研究目的。多导睡眠图检查期间,采用脑电图和其他传感器将睡眠分为明确的几个阶段。最初的睡眠分期出现在20世纪30年代,1968年首次发布了对睡眠进行分期的正式规则。自2007年以来,大多数睡眠实验室使用来自美国睡眠医学学会(American Academy of Sleep Medicine, AASM)睡眠和相关事件判读手册的术语和判读规则,该手册会常规更新。AASM认证的睡眠实验室被要求采用AASM判读手册,全世界正越来越多地采纳这些指南。


  本专题将总结当前的成人睡眠分期指南、睡眠结构、睡眠分期异常的常见原因以及围绕睡眠目的的理论。睡眠障碍的分类见其他专题。 (参见“睡眠障碍的分类”)


  睡眠分期 — 睡眠可宽泛地分为快速眼动(rapid eye movement, REM)睡眠期和非快速眼动(non-rapid eye movement, NREM)睡眠期。根据当前的AASM判读规则,以30秒为一帧来评判睡眠分期。目前规则要求使用脑电图、肌电图(electromyography, EMG)和眼电图(electrooculography, EOG)来确定睡眠分期,肌电图用于检测肌张力,眼电图检测眼运动。这在将来可能会发生改变以更好地将睡眠列为一个连续的过程,这可通过着重关注睡眠的更短时帧或通过睡眠脑电图的频谱分析来实现。


  典型的30秒睡眠检测数据记录帧见图所示(图 1)。


  Stage wake


  https://picb.zhimg.com/v2-a8c4799055d893e31839e0d27cd05360_b.jpg


  根据国际10-20系统,采集脑电图数据的电极放置在头的额部、中央部和枕部并参考骨的解剖位置定位(图 2)。


  International electrode placement system


  https://pic4.zhimg.com/v2-9dc110d117a0665dcb95c1276ca1895f_b.jpg


  作为该系统的一部分,奇数表示头左侧,偶数表示右侧;通常,脑电图要求双侧监测,因为左右大脑半球可能不会提供完全相同的数据。虽然完整的脑电图监测需要放置所有的10-20系统电极,但进行睡眠分期时仅需放置上述部分电极组(F3和F4,C3和C4,O1和O2)。脑波通过振幅和频率来评估;不同频率与不同睡眠阶段相关(表 1)。


  Electroencephalography pattern labels and associated frequencies

  清醒期 — 通常,成人在一天24小时中至少有2/3的时间是清醒的。行为线索(包括睁眼、运动和会话)说明警觉状态。然而,随着活动减弱,人会躺下来并闭上双眼。此时,脑波减慢至稳定的后部α节律(图 1)。这个节律是清醒与睡眠之间的过渡。当这个节律进一步减慢时,达到睡眠状态。部分成人不会产生后部α节律,因而分期更加困难。


  NREM睡眠期 — 大多数成人会从昏昏欲睡状态经NREM睡眠期进入睡眠。NREM睡眠期可细分为3个亚期:N1期、N2期和N3期。值得注意的是,较早的规则将NREM睡眠分为4期;目前的规则将以往的NREM 3期和NREM 4期合并为N3期。


  N1期 — N1期睡眠是从觉醒状态到睡眠的典型过渡期。其特征是低振幅混合性脑电波频率,处于θ波范围(4-7Hz),占一帧的至少50%(图 3)。眼动通常缓慢且为旋转运动。N1期是最浅的睡眠期;从该期醒来的患者通常不会察觉到他们实际上睡着过。在年轻成人中,N1期睡眠通常占总睡眠时间的5%-10%或以下。


  多导睡眠图检测时N1期睡眠占比增加可能提示睡眠片段化疾病,如阻塞性睡眠呼吸暂停。然而,这也可能是患者正在进行心理调整以适应睡眠实验室监测的“首夜效应(first night effect)”。


  Stage N1 sleep


  Stage N1 sleep


  N2期 — N2期通常在正常中年成人的总睡眠时间中占比最大,通常占一夜时间的45%-55%。其特征是θ波脑电图频率。


  在N2期,有2个首次出现在脑电图上的NREM睡眠的鉴别特征:睡眠梭形波和K复合波。


  ●睡眠梭形波通常较短(但至少有0.5秒),脑电图频率为11-16Hz(最常为12-14Hz)(图 4)。这些波在中央部(头顶)脑电图导联中最为突出。


  ●K复合波是清晰可辨的负向尖波,其后紧接一个正向波,凸显在背景脑电图中,总持续时间大于等于0.5秒(图 5)。K复合波通常在额区脑电图的振幅最大。


  苯二氮卓类药物可增加N2期睡眠。通常,苯二氮卓类药物可引起梭形波电活动增加。 (参见“药物对睡眠质量和睡眠结构的影响”,关于‘苯二氮卓类和非苯二氮卓类受体激动剂’一节)


  Stage N2 sleep: Spindle

  Stage N2 sleep: K-complex


  N3期 — N3期睡眠常被称为“深度睡眠”或“慢波睡眠”。其特征为低频率(0.5-2Hz)、高振幅(>75μV)的δ波,占一个既定睡眠帧的至少20%(图 6)。N3期睡眠通常占青年至中年成人总睡眠时间的10%-20%,并随年龄增加而减少。


  N3期往往更多见于前半夜,尤其是入夜时分,因为睡眠期间的慢波活动代表睡眠的内平衡驱力(homeostatic drive),该驱力在觉醒期后达到最大。唤醒N3期睡眠者常常比唤醒N1和N2期睡眠者更困难,N3期是NREM睡眠异态出现的典型时间。 (参见“儿童睡行症及其他深眠状态”)


  Stage N3 Sleep


  REM睡眠期(R期) — REM睡眠期(也称R期)有3个主要特征,这些特征需由脑电图、眼电图和肌电图来捕获。


  ●脑电图呈现低电压、混合性脑电图模式。锯齿状波是REM睡眠期的常见发现;这些2-6Hz的波外形尖锐,呈短暂暴发模式。


  ●REM是该睡眠期的界定特征。眼电图上,这些REM被定义为共轭的、不规则的尖峰眼球运动,初始阶段不足500毫秒。


  ●肌电图显示肌张力低下,表示所有随意肌不活动(除眼外肌和膈肌外)。肌张力低下是α运动神经元受到直接抑制的结果。


  REM睡眠有2相:位相性(phasic)和紧张性(tonic)。位相性REM睡眠包含REM暴发、呼吸变异性以及短暂肌电图活动(偶尔表现为肌肉颤搐)(图 7)。紧张性REM睡眠期出现的运动活动更加有限,伴有少数几次眼动(图 8)。


  Stage R Sleep Phasic

  Stage R Sleep Tonic


  根据将患者从REM睡眠中唤醒的早期研究,REM睡眠通常有生动梦境。虽然REM睡眠期占总睡眠时间不足1/4(18%-23%),但该睡眠期的功能仍存在争论。一个假设提出REM睡眠期是记忆巩固时间,此时将保留重要的记忆,去除不太重要的神经连接。


  REM睡眠可细分为位相性REM睡眠和紧张性REM睡眠。位相性REM睡眠是REM睡眠的一部分,期间存在REM暴发,这可能与肌电图活动的短暂暴发(有时称作颤搐)和/或交感神经活动骤增有关。紧张性REM睡眠是REM睡眠的一部分,出现在两次位相性暴发的间期,该时期的肌张力始终较低。


  几种睡眠障碍可能与REM睡眠异常或REM睡眠相关的生理性事件有关:


  ●发作性睡病–发作性睡病患者常在其睡眠结构的极早期甚至是短暂的日间小睡中出现REM睡眠。 (参见“成人发作性睡病的临床特征和诊断”)


  ●阻塞性睡眠呼吸暂停–REM相关肌张力低下可能会损害上气道通畅性,明显增加阻塞性呼吸事件的发生频率。REM睡眠期间脑对氧信号的反应较差还可能导致呼吸事件持续时间延长。


  ●肺疾病–REM相关的肌张力低下可延伸至累及肋间肌及辅助呼吸肌。这对以下患者有潜在重要的意义:存在呼吸力学异常导致其必须依赖自身肋间肌和辅助呼吸肌来维持可接受的通气水平的患者(如慢性阻塞性肺疾病、胸壁疾病或神经肌肉障碍患者)。在REM睡眠期间,这类患者可能出现通气不足和氧合血红蛋白去饱和。 (参见“COPD中的睡眠呼吸障碍”和“神经肌肉和胸壁疾病患者睡眠呼吸障碍的评估”)


  ●REM睡眠行为障碍–若REM睡眠期间肌肉松弛不完全或无松弛,则患者可能“表演出”其梦境。这可能导致患者或床伴受伤害。 (参见“快动眼睡眠相睡眠行为障碍”)


  酒精、镇静催眠药、巴比妥类及其他抗癫痫药、β受体拮抗剂、单胺氧化酶抑制剂、选择性5-羟色胺再摄取抑制剂和兴奋剂可能会延迟或抑制REM睡眠。有显著抗胆碱能作用的药物(如三环类抗抑郁药)也可能延迟或抑制REM睡眠。然而,REM睡眠中这些变化的临床意义还不清楚,因为患者不会出现REM睡眠剥夺的典型表现。相反,停用酒精、苯二氮卓类药物、三环类抗抑郁药或单胺氧化酶抑制剂可增加REM睡眠。 (参见“药物对睡眠质量和睡眠结构的影响”)


  觉醒 — 睡眠期交替转换。随着睡眠进行性加深,特定的脑电图、眼电图和肌电图表现将会变得明显,如前面章节所述。或者,觉醒将会出现,将个体从较深的睡眠带到较浅的睡眠或觉醒状态(图 9)。


  觉醒由特定标准来确定。在N1、N2、N3或R期睡眠中,如果脑电图频率出现突然变化(包括α波、θ波和/或频率超过16Hz的脑电波,但不包括梭形波)且持续至少3秒,并且在变化前须有持续至少10秒的稳定睡眠,则可判读为觉醒。在REM期间判读觉醒还需要同时出现颏下肌电图波幅增加且持续至少1秒。


  睡眠结构 — 睡眠不是同质性的过程,在任何一夜,睡眠似乎会经过多个明确的周期。这些周期以相当典型的NREM和REM睡眠模式出现,单个周期持续90-120分钟。例如,第1个睡眠周期通常包括从入睡开始直至患者脱离第1个REM期的这段时间。一个典型的8小时夜间睡眠会出现4-5个周期(图 10)。


  Hypnogram of a 36-year-old man in a sleep laboratory


  https://picb.zhimg.com/v2-4b2cca2fce76881ed8338560df26cb14_b.jpg


  睡眠周期以下列方式贯穿一个标准夜晚:


  ●夜间的第1个周期始于从清醒至N1期的过渡阶段,然后进入N2期、N3期,随后是REM。


  ●随着夜间周期的继续循环,每个周期中REM睡眠占比通常会增加。


  ●随着夜晚时间推移,N3期占比趋于减少,N3期在前半夜的占比最大。


  睡眠结构也随年龄不同而有差异(图 11)。新生儿每日睡16-18小时,断断续续,没有明确的昼夜时相。他们往往经REM而非NREM睡眠期进入睡眠。3月龄左右,他们开始出现日/夜周期,经NREM睡眠期进入睡眠。总睡眠时间缓慢减少,最终在青春期后达到成人标准值。 (参见“儿童睡眠生理”,关于‘睡眠结构的成熟’一节)


  Graphic representation of the changes of sleep as humans age

  年轻成人通常每晚睡眠约8个小时,N3期睡眠占比升高;步入中年及以后,N3期睡眠占比减小,清醒和N1期占比增加。然而,值得注意的是,REM睡眠占比在整个成年期都相当稳定。虽然常常想当然地认为年龄较大成人所需的总睡眠时间减少,但年轻成人和年龄较大成人所需的总睡眠时间似乎并无显著差异。


  正常睡眠结构与某些睡眠障碍有关。例如,NREM相关睡眠异态更有可能出现于前半夜,往往在最初1小时或2小时内,此时N3期睡眠最常见。相比之下,REM相关睡眠异态往往更常出现于后半夜,此时REM睡眠占比更高。阻塞性睡眠呼吸暂停也可能在后半夜更为突出,此时REM相关生理变化加重了睡眠呼吸障碍。


  多导睡眠图显示的睡眠结构可能并不反映患者在家的正常睡眠情况,认识到这一点很重要;因此,一个检测夜晚中REM睡眠减少不一定具有临床意义。然而,在其他情况下,睡眠结构变化可反映潜在睡眠障碍、躯体疾病或某种物质的影响。例如:


  ●入睡开始后不久即出现的REM睡眠提示发作性睡病、抑郁、停药后REM反跳或者昼夜节律紊乱。


  ●睡眠片段化疾病,如阻塞性睡眠呼吸暂停或周期性肢动,往往会增加睡眠期的变化次数,可能完全破坏睡眠正常周期。


  ●先前的急性或慢性睡眠剥夺可能引起N3期睡眠和REM睡眠增加。


  ●摄入或停用某些药物(如三环类抗抑郁药、单胺氧化酶抑制剂)或物质(如咖啡因、酒精)可对睡眠结构造成明显影响。


  ●心境可影响睡眠,因此重性抑郁患者的REM睡眠潜伏期可能缩短。


  睡眠和生理学 — 上文讨论的分期命名不仅仅基于脑电图;NREM与REM睡眠之间似乎还存在生理学差异。一般而言,深NREM睡眠(N3)往往是呼吸和心血管稳定的时期。REM睡眠中,心率、呼吸频率、血压和通气更常出现不规则(表 2)。


  睡眠的潜在功能 — 对睡眠的真正目的了解甚少,目前存在多种理论。从进化角度来讲,动物不了解其周围环境的状态似乎是很危险的,不太可能作为一种特质得以延续。在所有动物种类中都观察到睡眠,这提示一定有某些积极的益处。


  睡眠不活动理论提出,睡眠是一种使动物存活的特性,因为它能使动物在有危险的时间段内保持在安全状态:昼出动物在夜晚不活动,此时其视力较低。然而,有些人可能会辩称任何时候无意识都不利于生存。另一个相关理论是能量节约理论:保持一段时间处于最小活动状态可节约代谢能量,尤其是当这种状态出现在难以获得食物的时候。人类中的观察结果似乎支持这一点:睡眠期间,体温和热量需求减小,因此节约了能量。


  恢复理论提出,在睡眠状态中身体会自我修复和恢复活力。从一整夜的睡眠中醒过来,个体通常觉得精力充沛。相反,睡眠不足会导致日间表现不佳,感觉疲劳或瞌睡,以及对免疫系统功能有可测量的影响。(参见“睡眠不足:定义、流行病学和不良结局”)睡眠期间生长激素分泌达到峰值;这可能促使夜间肌肉生长和细胞再生。睡眠期间脑代谢很可能通过清除某些物质(如腺苷)而发挥恢复功能的作用,腺苷会在日间积累并且很可能会帮助诱导深NREM睡眠。尤其是,睡眠似乎与间质间隙增加有关,从而改善神经毒性废物的清除。


  经验性和实验性数据也提示,睡眠可通过促进学习依赖性突触形成和维持而在脑可塑性方面发挥作用。睡眠不足时,人类的学习状况明显不太好;因此睡眠一定对认知功能和记忆有影响。新生儿用更多时间来睡眠,尤其是REM睡眠占比更高。一些人认为,做梦期间出现的感觉输入,以及运动皮质活动(在正常REM睡眠中其本身在外周的表达受阻滞)在脑发育中发挥重要作用。同时,NREM睡眠可能通过将饱和的学习回路恢复至基线水平而对学习产生影响。


  总结


  ●睡眠以每30秒为一帧进行分析,每帧均可分为快速眼动(REM)睡眠或非快速眼动(NREM)睡眠。 (参见上文‘睡眠分期’)


  ●NREM睡眠分为3期:N1期、N2期和N3期。第4期(N4)仅为以前使用旧的判读标准划分的阶段,新的标准已将N4期并入N3期。NREM睡眠通常占成人总睡眠时间的大部分。 (参见上文‘NREM睡眠期’)


  ●REM睡眠每90-120分钟出现1次。REM睡眠有以下3个主要特征:低电压混合频率脑电图模式、REM和随意肌张力低下(除眼外肌和膈肌外)。虽然REM睡眠仅占总睡眠时间的少部分,但在生理稳态和认知方面有重要作用。 (参见上文‘REM睡眠期(R期)’)


  ●睡眠期以周期形式循环出现,每个周期持续90-120分钟。一个典型的夜间睡眠通常有4-5个周期。睡眠期的转换出现于整夜间,通常在前半夜NREM睡眠的占比增加(尤其是N3期),在后半夜REM睡眠的占比增加。典型睡眠结构的变化可能反映睡眠障碍,但也存在许多其他原因。 (参见上文‘睡眠结构’)


  ●对睡眠的真正目的了解甚少。经验性和实验性数据支持多种潜在功能,包括节约能量、恢复机体、清除代谢物以及促进脑可塑性。 (参见上文‘睡眠的潜在功能’)


  参考文献


  Siegel JM. Sleep viewed as a state of adaptive inactivity. Nat Rev Neurosci 2009; 10:747.


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  Ohayon MM, Carskadon MA, Guilleminault C, Vitiello MV. Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals: developing normative sleep values across the human lifespan. Sleep 2004; 27:1255.


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  专题 7710 版本 18.0.zh-Hans.1.0


  图表


  Stage wake


  This image demonstrates a 30-second recording (Compumedics) of stage wake with eyes closed, notable for the alpha activity occurring the occipital leads (labeled O2-M1 and O1-M2). The top two leads represent the eyes (right and left), the next lead is the chin, then the following six leads are EEG (right and left frontal, central, and occipital), ECG with heart rate below (R-R), and the leg EMG lead.


  EEG: electroencephalogram; ECG: electrocardiogram; EMG: electromyography.


  Graphic 103287 Version 1.0


  International electrode placement system


  The location of electrodes for recording electroencephalograms from the scalp, nasopharyngeal, and external ear sites are shown. The leads placed on the zygomatic arch beneath the eye allow for monitoring of eye movements.


  Adapted from: Jasper HH. Report of the committee on methods of clinical examination in electroencephalography: 1957. Electroencephalogr Clin Neurophysiol 1958; 10:370.


  Graphic 78990 Version 2.0


  Electroencephalography pattern labels and associated frequencies


  EEG pattern


  Stage N1 sleep

  This image demonstrates a 30-second recording (Compumedics) of stage N1 sleep, notable for the theta activity throughout the first three quarters of the epoch. An arousal occurs at that time (arrow), with a return of alpha activity. The top two leads represent the eyes (right and left), the next lead is the chin, then the following six leads are EEG (right and left frontal, central, and occipital), ECG with heart rate below (R-R), and the leg EMG lead.


  EEG: electroencephalogram; ECG: electrocardiogram; EMG: electromyography.


  Graphic 103288 Version 1.0


  Stage N2 sleep: Spindle

  This image demonstrates a 30-second recording (Compumedics) of stage N2 sleep. Most notable is the beta-frequency spindle activity (dashed box), maximally seen in the central EEG leads. The top two leads represent the eyes (right and left), the next lead is the chin, then the following six leads are EEG (right and left frontal, central, and occipital), ECG with heart rate below (R-R), and the leg EMG lead.


  EEG: electroencephalogram; ECG: electrocardiogram; EMG: electromyography.


  Graphic 103289 Version 1.0


  Stage N2 sleep: K-complex


  This image demonstrates a 30-second recording (Compumedics) of stage N2 sleep. Most notable are the K-complexes (dashed boxes), maximally seen in the frontal and central EEG leads. The top two leads represent the eyes (right and left), the next lead is the chin, then the following six leads are EEG (right and left frontal, central, and occipital), ECG with heart rate below (R-R), and the leg EMG lead.


  EEG: electroencephalogram; ECG: electrocardiogram; EMG: electromyography.


  Graphic 103290 Version 2.0


  Stage N3 sleep


  This image demonstrates a 30-second recording (Compumedics) of stage N3 sleep. Most notable are the delta waves throughout the EEG recording (background shading), maximal in the frontal leads. The top two leads represent the eyes (right and left), the next lead is the chin, then the following six leads are EEG (right and left frontal, central, and occipital), ECG with heart rate below (R-R), and the leg EMG lead.


  EEG: electroencephalogram; ECG: electrocardiogram; EMG: electromyography.


  Graphic 103291 Version 1.0


  Stage R sleep: Phasic


  This image demonstrates a 30-second recording (Compumedics) of stage R sleep. Most notable is the cluster of rapid eye movements noted in the eye leads (background shading). The top two leads represent the eyes (right and left), the next lead is the chin, then the following six leads are EEG (right and left frontal, central, and occipital), ECG with heart rate below (R-R), and the leg EMG lead.


  EEG: electroencephalogram; ECG: electrocardiogram; EMG: electromyography.


  Graphic 103292 Version 1.0


  Stage R sleep: Tonic


  This image demonstrates a 30-second recording (Compumedics) of stage R sleep. Most notable is the absence of rapid eye movements noted in the eye leads (labeled E2-M2 and E1-M2) or phasic EMG activity. The top two leads represent the eyes (right and left), the next lead is the chin, then the following six leads are EEG (right and left frontal, central, and occipital), ECG with heart rate below (R-R), and the leg EMG lead.


  EEG: electroencephalogram; ECG: electrocardiogram; EMG: electromyography.


  Graphic 103293 Version 1.0


  Arousal from sleep


  https://picb.zhimg.com/v2-d7dda00662000853a0a07a0f5f7945b5_b.jpg


  This image demonstrates a 30-second recording (Compumedics) of stage N2 sleep. Most notable is the arousal that occurs at the solid arrow, with a switch from theta EEG activity to alpha EEG activity. The top two leads represent the eyes (right and left), the next lead is the chin, then the following six leads are EEG (right and left frontal, central, and occipital), ECG with heart rate below (R-R), and the leg EMG lead.


  EEG: electroencephalogram; ECG: electrocardiogram; EMG: electromyography.


  Graphic 103294 Version 2.0


  Hypnogram of a 36-year-old man in a sleep laboratory


  This hypnogram represents the movement of a patient through various sleep cycles over the course of a single night; from approximately 10:37 pm to 5:36 am. The stages are listed as W (wake), R (REM sleep, stage R), and N1-N3 (NREM stages N1, N2, and N3). The patient starts by transitioning from wake into light NREM sleep, then to deep NREM sleep, back to light NREM sleep and then into REM sleep. This pattern generally repeats itself with blocks of NREM and REM sleep approximately every 90 minutes.


  REM: rapid eye movement; NREM: non-REM.


  Graphic 95157 Version 5.0


  Graphic representation of the changes of sleep as humans age


  Age-related trends for stage 1 sleep, stage 2 sleep, slow wave sleep, rapid eye movement sleep, wake after sleep onset, and sleep latency (in minutes).


  WASO: wake after sleep onset; REM: rapid eye movement; SWS: slow wave sleep.


  Republished with permission of Associated Professional Sleep Societies, LLC, from Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals: developing normative sleep values across the human lifespan, Ohayon MM, Carskadon MA, Guilleminault C, Vitiello MV, Sleep 2004; 27:1255; permission conveyed through Copyright Clearance Center, Inc.


  Graphic 103345 Version 1.0


  Physiologic effects of sleep stage


  NREM sleep


  REM sleep


  Autonomic nervous system


  Increased parasympathetic tone


  Unstable, brief surges in sympathetic and parasympathetic activity


  Cardiovascular system


  Heart rate is slow and regular


  Blood pressure is lower


  Heart rate is irregular


  Transient increases in blood pressure


  Respiratory system


  Mild decrease in ventilatory drive in response to hypoxia and hypercapnia


  Decreased respiratory rate


  Significant decrease in ventilatory drive in response to hypoxia and hypercapnia


  Increased respiratory rate


  Temperature regulation


  Decreased hypothalamic temperature set point


  Reduced thermoregulatory mechanisms


  Reproductive system


  Penile erections


  Increased vaginal blood flow


  Dreaming


  Less vivid


  More vivid, visually intense


  REM: rapid eye movement; NREM: non-REM.


  Data from: Benca R. Sleep Disorders: The Clinician's Guide to Diagnosis and Management. Oxford University Press, New York. 2012.


  Graphic 95155 Version 3.0


  编辑于 2018-04-25



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