You jerk awake in the middle of the night in confusion. Is there a figure standing in the corner of the room? Your brain begs your limbs to move, but nothing happens. The anxiety increases. Your eyes scan the room. Just as you’re about to hit peak panic, you sit up and the figure disappears.

You’ve just experienced sleep paralysis, one of many “parasomnias,” which is the name experts give to all sorts of weird things that occur during sleep.

Sleep paralysis happens when the brain incapacitates the body to prevent it from acting out the vivid dreams occurring during REM (or, rapid eye movement) sleep. It often comes with a feeling of immobility and a sense of choking.

The good news is, it’s absolutely normal. Even if it’s terrifying.

But when sleep paralysis happens outside of deep sleep — when a person is just dozing off or waking up — it can be “disruptive of the architecture of sleep,” said Baland Jalal, a researcher who investigates the phenomenon. That could lead to more sleep paralysis. People with poor sleeping habits experience the phenomenon more frequently.

While the mechanisms behind sleep paralysis remain murky, Jalal said stress and worry play a part. Recent research indicates that people with anxiety and PTSD report experiencing sleep paralysis more frequently.

“People who are anxious have much more emotional sleep. [They] are more likely to wake up during REM,” said Jalal.

The anxiety feeds into the sleep paralysis, said Jalal. People fret about experiencing the panicky feelings of sleep paralysis, which makes it more likely to occur again.

While about 6 percent of the population will experience sleep paralysis at one point in their lives, it occurs in about 30 to 50 percent of people with narcolepsy, a sleep disorder that includes excessive daytime sleepiness, cataplexy, sleep paralysis, and hallucinations, said Dr. Nathaniel Watson, president of the American Academy of Sleep Medicine and co-director of the University of Washington Medical Sleep Center.

Words to Learn 相关词汇

【使无能力】shǐ wú nénglì incapacitate to deprive of ability, qualification, or strength; make incapable or unfit; disable

【嗜睡症】 shìshuì zhèng narcolepsy a condition characterized by frequent and uncontrollable periods of deep sleep

半夜里你突然莫名其妙地惊醒。房间的角落似乎有个人影。你想要动动四肢，但却动弹不得。你越来越焦虑。你的眼睛扫视着房间。就在你的恐慌情绪即将达到顶峰时，你坐起来了，那个人影也消失了。

你刚刚经历了睡眠瘫痪，它是众多睡眠异常的一种。专家用睡眠异常来指代睡眠时发生的各种怪异事情。

大脑为了阻止身体对异相睡眠（或快速眼动睡眠）期的生动梦境做出回应而使身体失去活动能力时，就会发生睡眠瘫痪，常常伴随着一种无法行动的感觉和一种窒息感。

好消息是，睡眠瘫痪虽然很恐怖，但绝对是正常现象。

但是，研究这一现象的科研人员巴拉德·贾拉尔说，当睡眠瘫痪发生在深度睡眠之外——例如当一个人只是打瞌睡或快要醒来时——它可能会“破坏睡眠结构”。这可能会引发更多次的睡眠瘫痪。睡眠习惯差的人则会更频繁地经历这种现象。

贾拉尔说，虽然对睡眠瘫痪背后的机制依然没有头绪，但压力和担忧是导致睡眠瘫痪的原因之一。最近的研究表明，患有焦虑症和创伤后应激障碍的人会更频繁地出现睡眠瘫痪。

贾拉尔说:“焦虑的人在睡觉时受到更多情绪影响，他们更有可能在异相睡眠期间醒来。”

贾拉尔说，焦虑会加剧睡眠瘫痪情况的发生。人们担心会经历睡眠瘫痪的恐慌感，这反而会使它更有可能再次发生。

美国睡眠医学研究院院长、华盛顿大学医学睡眠中心联合主任纳撒尼尔·沃森博士说，虽然大约6%的人一生中会在某个时候经历睡眠瘫痪，但大约30%到50%的嗜睡症患者中会出现睡眠瘫痪。嗜睡症的症状包括白天过度困倦、昏睡、睡眠瘫痪和出现幻觉。(chinadaily.com.cn)