Glad is to ecstasy as fear is to terror. Pretty much everyone has had a nightmare or two at some point, but night terrors take things to a frightening new level. Categorized as a type of parasomnia, night terrors (also referred to as sleep terrors, pavor nocturnus, or AXIS I: 307.46 per the DSM’s psychiatric code) are debilitating panic attacks that happen during non-REM hours of sleep. Unlike nightmares, the sufferer usually does not recall the event upon waking, but anyone who is with them during an episode most certainly will.

Night terrors usually occur during the first three to four hours of sleep while the brain has not fully entered deep, REM sleep. The person may flail their appendages or incur full-body spasms, cry out vocally, or even arise from the bed in extreme sleepwalking episodes. Physiological symptoms like elevated heart rate, rapid breathing, flushing and sweating, and dilation of the pupils can occur. It sounds like perfect fodder for the development of myths of demonic possession and truly the stuff of horror movies, but for the individual, it is distinctly real. While they may not recall a single thing that happened overnight, there are underlying problems that need to be addressed; both to prevent further attacks that disrupt restorative sleep and to confront what issues may be at fault for causing the terrors to begin with.

If you’ve never experienced a night terror, you’re lucky. You’re also in the majority. According to the American Academy of Sleep Medicine, only slightly over two percent of adults will ever endure a true night terror. They are more common in children (although, still, at just over six percent), but it seems that many youths are able to outgrow the disorder. Much has been learned about these episodes thanks to extensive research determining that the terrors result from over-arousal of the central nervous system. In children, this can be attributed to developmental issues and is thus why some people cease experiencing them as they mature and their CNS becomes fully developed. For those who continue suffering into adulthood, the reasons could be endless—anything from poor sleep habits, drug or alcohol abuse, PTSD, and that catch-all aggravator that is almost impossible to escape: stress.

In many cases, there is little reason to catastrophize night terrors. If they only happen intermittently, they are probably causing you only as much harm as a regular nightmare. But if they are chronic or extreme, you run the risk of both the aftermath of cumulative inadequate sleep as well as physical harm from unpredictable and spastic outbursts. In these cases, it is best to rid the bedroom of sharp corners and potential hazards.

Though night terrors remain somewhat of a mystery, there are things you can do to help prevent an attack. Some best practices advised to overcome any sleep disruption: establish a regular bedtime routine, eliminate stress as much as possible, avoid caffeine, drugs, and alcohol (especially near bedtime), and practice a healthy exercise regime to encourage exhausting pent-up energies. If episodes continue to haunt you after adjusting those elements of behavior, it is best to see a certified sleep specialist who can work on a program that will alleviate these unfortunate events from your nightly repose.

No one wants to be terrified at any point throughout their daily activities, but a debilitating fright out of their control that disrupts one’s sleep definitely tops the undesirability list. Seek professional help if necessary, and keep the horror at the movie theatre where it belongs.