In the wee hours of the morning, you wake suddenly from sleep, overcome by a strange feeling of dread. You\u2019re sure there\u2019s an intruder in your bedroom and spot a terrifying creature at the end of your bed.\nYet you can\u2019t move a muscle \u2014 or even scream. It may sound like something out of a horror flick, but this experience, known as sleep paralysis, is a very real phenomenon. While harmless, this problem can be very frightening and the fear of having an episode may interfere with a good night\u2019s sleep.\nWhat Is Sleep Paralysis?\nSleep paralysis is a type of parasomnia, or sleep disorder. It typically occurs when you are either falling asleep (hypnogogic) or when you are waking up (hypnopompic). During both of these times, your eyes move quickly and dreams occur as part of rapid eye movement (REM) sleep, but your muscles are very relaxed.\nIf you wake up\u00a0before this stage ends, you may realize that you are unable to move or speak. A subset of people also experience hallucinations. These can include:\n\nA feeling of foreboding\nThe sense that someone is in your room\nThe sensation of something pressing on your chest or choking you\nAn image of a monster, witch, demon, or other menacing figure\n\nAlthough it\u2019s still unclear why or how these hallucinations occur, researchers believe a harmless neurological disturbance may be involved. An episode of sleep paralysis can last anywhere from a few seconds to a few minutes.\nRELATED:\u00a0Infographic: 6 Common Sleep Disorders\nWhat Causes Sleep Paralysis?\nSleep paralysis is quite common: Surveys found that about 40 percent of people have had the problem at some point in their lives. In fact, almost every culture has some sort of story or explanation for the experience, ranging from vengeful spirits to alien abductors. Folklore aside, a number of factors can increase your likelihood of having sleep paralysis.\nOne of the major causes of sleep paralysis is sleep deprivation, or a lack of sleep. A changing sleep schedule, sleeping on your back, the use of certain medications, stress, and other sleep-related problems, such as narcolepsy, may also play a role.\nSleep Paralysis Treatment and Prevention\nIt\u2019s normal to experience occasional episodes of sleep paralysis, and no treatment is necessary. If you have another sleep disorder, treating that problem will usually help prevent paralysis as well. The most important thing you can do to reduce your risk of having an episode is to get plenty of sleep \u2014 at least eight hours per night. You should also try keeping a lid on stress and switching to a new position if you typically sleep on your back. If you are troubled by frequent episodes of sleep paralysis, your doctor may recommend that you see a sleep specialist for further evaluation.\nHaving trouble sleeping? What keeps you up at night? Learn more about sleep disorders and speak with an expert to get to the root of your sleeping problem. Visit the UPMC Sleep Medicine Center online and make an appointment today.