WEBVTT 00:00:06.000 --> 00:00:08.000 Imagine this: 00:00:08.000 --> 00:00:10.000 You're fast asleep 00:00:10.000 --> 00:00:12.000 when all of a sudden you're awoken! 00:00:12.000 --> 00:00:14.000 And not by your alarm clock. 00:00:14.000 --> 00:00:15.000 Your eyes open, 00:00:15.000 --> 00:00:17.000 and there's a demon sitting on your chest, 00:00:17.000 --> 00:00:19.000 pinning you down. 00:00:19.000 --> 00:00:21.000 You try to open your mouth and scream, 00:00:21.000 --> 00:00:22.000 but no sound comes out. 00:00:22.000 --> 00:00:24.000 You try to get up and run away, 00:00:24.000 --> 00:00:27.000 but you realize that you are completely immobilized. 00:00:27.000 --> 00:00:29.000 The demon is trying to suffocate you, 00:00:29.000 --> 00:00:31.000 but you can't fight back. 00:00:31.000 --> 00:00:33.000 You've awoken into your dream, 00:00:33.000 --> 00:00:35.000 and it's a nightmare. 00:00:35.000 --> 00:00:38.000 It sounds like a Stephen King movie, 00:00:38.000 --> 00:00:39.000 but it's actually a medical condition 00:00:39.000 --> 00:00:41.000 called sleep paralysis, 00:00:41.000 --> 00:00:43.000 and about half of the population 00:00:43.000 --> 00:00:44.000 has experienced this strange phenomenon 00:00:44.000 --> 00:00:46.000 at least once in their life. 00:00:46.000 --> 00:00:48.000 This panic-inducing episode 00:00:48.000 --> 00:00:50.000 of coming face-to-face with the creatures 00:00:50.000 --> 00:00:52.000 from your nightmares 00:00:52.000 --> 00:00:54.000 can last anywhere from seconds to minutes 00:00:54.000 --> 00:00:57.000 and may involve visual or auditory hallucinations 00:00:57.000 --> 00:00:59.000 of an evil spirit 00:00:59.000 --> 00:01:01.000 or an out-of-body feeling like you're floating. 00:01:01.000 --> 00:01:03.000 Some have even mistaken sleep paralysis 00:01:03.000 --> 00:01:05.000 for an encounter with a ghost 00:01:05.000 --> 00:01:08.000 or an alien abduction. 00:01:08.000 --> 00:01:11.000 In 1867, Dr. Silas Weir Mitchell 00:01:11.000 --> 00:01:13.000 was the first medical professional 00:01:13.000 --> 00:01:15.000 to study sleep paralysis. 00:01:15.000 --> 00:01:18.000 "The subject awakes to consciousness 00:01:18.000 --> 00:01:19.000 of his environment 00:01:19.000 --> 00:01:21.000 but is incapable of moving a muscle. 00:01:21.000 --> 00:01:24.000 Lying to all appearance, still asleep. 00:01:24.000 --> 00:01:27.000 He's really engaged for a struggle for movement, 00:01:27.000 --> 00:01:30.000 fraught with acute mental distress. 00:01:30.000 --> 00:01:32.000 Could he but manage to stir, 00:01:32.000 --> 00:01:34.000 the spell would vanish instantly." 00:01:34.000 --> 00:01:36.000 Even though Dr. Mitchell was the first 00:01:36.000 --> 00:01:38.000 to observe patients in a state of sleep paralysis, 00:01:38.000 --> 00:01:41.000 it's so common that nearly every culture 00:01:41.000 --> 00:01:42.000 throughout time has had some kind 00:01:42.000 --> 00:01:45.000 of paranormal explanation for it. 00:01:45.000 --> 00:01:48.000 In medieval Europe, you might think that an incubus, 00:01:48.000 --> 00:01:50.000 a sex-hungry demon in male form, 00:01:50.000 --> 00:01:52.000 visited you in the night. 00:01:52.000 --> 00:01:54.000 In Scandinavia, the mare, 00:01:54.000 --> 00:01:56.000 a damned woman, 00:01:56.000 --> 00:01:57.000 is responsible for visiting sleepers 00:01:57.000 --> 00:02:00.000 and sitting on their rib cages. 00:02:00.000 --> 00:02:02.000 In Turkey, a jinn holds you down 00:02:02.000 --> 00:02:04.000 and tries to strangle you. 00:02:04.000 --> 00:02:08.000 In Thailand, Phi Am bruises you while you sleep. 00:02:08.000 --> 00:02:09.000 In the southern United States, 00:02:09.000 --> 00:02:12.000 the hag comes for you. 00:02:12.000 --> 00:02:13.000 In Mexico, you could blame 00:02:13.000 --> 00:02:16.000 subirse el muerto, the dead person, on you. 00:02:16.000 --> 00:02:18.000 In Greece, Mora sits upon your chest 00:02:18.000 --> 00:02:20.000 and tries to asphyxiate you. 00:02:20.000 --> 00:02:22.000 In Nepal, Khyaak the ghost 00:02:22.000 --> 00:02:24.000 resides under the staircase. 00:02:25.000 --> 00:02:26.000 It may be easier to blame 00:02:26.000 --> 00:02:28.000 sleep paralysis on evil spirits 00:02:28.000 --> 00:02:30.000 because what's actually happening in your brain 00:02:30.000 --> 00:02:32.000 is much harder to explain. 00:02:32.000 --> 00:02:34.000 Modern scientists believe that sleep paralysis 00:02:34.000 --> 00:02:36.000 is caused by an abnormal overlap 00:02:36.000 --> 00:02:38.000 of the REM, rapid eye movement, 00:02:38.000 --> 00:02:40.000 and waking stages of sleep. 00:02:40.000 --> 00:02:43.000 During a normal REM cycle, 00:02:43.000 --> 00:02:45.000 you're experiencing a number of sensory stimuli 00:02:45.000 --> 00:02:47.000 in the form of a dream, 00:02:47.000 --> 00:02:49.000 and your brain is unconscious and fully asleep. 00:02:49.000 --> 00:02:51.000 During your dream, 00:02:51.000 --> 00:02:53.000 special neurotransmitters are released, 00:02:53.000 --> 00:02:56.000 which paralyze almost all of your muscles. 00:02:56.000 --> 00:02:58.000 That's called REM atonia. 00:02:58.000 --> 00:02:59.000 It's what keeps you from running in your bed 00:02:59.000 --> 00:03:02.000 when you're being chased in your dreams. 00:03:02.000 --> 00:03:04.000 During an episode of sleep paralysis, 00:03:04.000 --> 00:03:07.000 you're experiencing normal components of REM. 00:03:07.000 --> 00:03:09.000 Your dreaming and your muscles are paralyzed, 00:03:09.000 --> 00:03:12.000 only your brain is conscious and wide awake. 00:03:12.000 --> 00:03:14.000 This is what causes you to imagine 00:03:14.000 --> 00:03:15.000 that you're having an encounter 00:03:15.000 --> 00:03:17.000 with a menacing presence. 00:03:17.000 --> 00:03:19.000 So this explains the hallucinations, 00:03:19.000 --> 00:03:21.000 but what about the feelings of panic, 00:03:21.000 --> 00:03:22.000 strangling, 00:03:22.000 --> 00:03:23.000 choking, 00:03:23.000 --> 00:03:24.000 chest pressure 00:03:24.000 --> 00:03:26.000 that so many people describe? 00:03:26.000 --> 00:03:28.000 Well during REM, 00:03:28.000 --> 00:03:28.000 the function that keeps you 00:03:28.000 --> 00:03:30.000 from acting out your dreams, 00:03:30.000 --> 00:03:32.000 REM atonia, 00:03:32.000 --> 00:03:33.000 also removes voluntary control 00:03:33.000 --> 00:03:35.000 of your breathing. 00:03:35.000 --> 00:03:36.000 Your breath becomes more shallow 00:03:36.000 --> 00:03:37.000 and rapid. 00:03:37.000 --> 00:03:39.000 You take in more carbon dioxide 00:03:39.000 --> 00:03:42.000 and experience a small blockage of your airway. 00:03:42.000 --> 00:03:44.000 During a sleep paralysis episode, 00:03:44.000 --> 00:03:46.000 a combination of your body's fear response 00:03:46.000 --> 00:03:48.000 to a perceived attack by an evil creature 00:03:48.000 --> 00:03:50.000 and your brain being wide awake 00:03:50.000 --> 00:03:53.000 while your body is in an REM sleep state 00:03:53.000 --> 00:03:56.000 triggers a response for you to take in more oxygen. 00:03:56.000 --> 00:03:57.000 That makes you gasp 00:03:57.000 --> 00:03:58.000 for air, 00:03:58.000 --> 00:03:59.000 but you can't 00:03:59.000 --> 00:04:00.000 because REM atonia 00:04:00.000 --> 00:04:03.000 has removed control of your breath. 00:04:03.000 --> 00:04:05.000 This struggle for air while your body sleeps 00:04:05.000 --> 00:04:07.000 creates a perceived sensation 00:04:07.000 --> 00:04:08.000 of pressure on the chest 00:04:08.000 --> 00:04:10.000 or suffocation. 00:04:10.000 --> 00:04:12.000 While a few people experience 00:04:12.000 --> 00:04:13.000 sleep paralysis regularly 00:04:13.000 --> 00:04:15.000 and it may be linked to sleep disorders 00:04:15.000 --> 00:04:17.000 such as narcolepsy, 00:04:17.000 --> 00:04:19.000 many who experience an episode of sleep paralysis 00:04:19.000 --> 00:04:21.000 do so infrequently, 00:04:21.000 --> 00:04:23.000 perhaps only once in a lifetime. 00:04:23.000 --> 00:04:24.000 So you can rest easy, 00:04:24.000 --> 00:04:27.000 knowing that an evil entity is not trying 00:04:27.000 --> 00:04:27.000 to haunt, 00:04:27.000 --> 00:04:28.000 possess, 00:04:28.000 --> 00:04:28.000 strangle, 00:04:28.000 --> 00:04:30.000 or suffocate you. 00:04:30.000 --> 00:04:32.000 Save that for the horror films!