While your body sleeps, your mind continues to work overtime in strange and surprising ways. Chances are, at some point in your life you’ve encountered one of these odd sleep disorders, maybe more often than you would like. Throughout history, cultures and civilizations across the globe have been analyzing and interpreting what we do in our sleep. Superstition has played a role in that analysis, and while the sleeping mind still holds many mysteries, modern research has begun to unravel these behaviors, and why they may occur.
In order to understand where these strange behaviors originate, you will need to be aware of the cycle of sleep and how it affects your conscious and unconscious mind.
The Cycle Your Mind Makes in Sleep
A sleep cycle involves transitions between three different mental states: wakefulness, rapid eye movement (REM) sleep, and nonrapid eye movement sleep. REM is typically associated with dreams, whereas non-REM is considered the “deep sleep”. In both the REM and non-REM state, your mind and body can do some pretty weird things, some of which you won’t remember at all by the time you wake up.
Nightmares and Sleep Terrors
Many people, especially children, can attest to the terror that nightmares cause. Nightmares can be a one-time experience, or they can be recurring, and they can be characterized by their vivid and disturbing content. Nightmares are more common in children, but they can also affect adults.
In 60% of cases, a major life event precedes the onset of nightmares, which leads researchers to believe that they are a result of anxiety and stress. Some other causes may be an illness with a fever, excess alcohol consumption, reaction to medication, breathing disorder during sleep, and eating just before bed.
Sleep terrors are different than nightmares in that they occur during non-REM sleep, while nightmares typically happen during REM sleep. Sleep terrors usually occur early in the night and can include arousal, agitation, large pupils, sweating and increased blood pressure for the sleeper. The sleeper typically does not remember the dream by the time they wake up.
Sleep terrors share the same root causes as sleepwalking and are linked to genetics. They may be caused by head injury, hyperthyroidism, stress, other sleeping disorders, fevers and medication.
Sleep talking, formally known as somniloquy, is the process of talking during sleep without being aware of it. It can involve complicated dialogues or complete gibberish and mumbling, and it’s most common in males and children. The sleeper is not typically aware that they are speaking, so the speech and type of language can often sound different than the waking voice. Sleep talking doesn’t interrupt your sleep pattern, but be careful not to spill all of your secrets to those listening!
Sleep talking often runs in the family and can be brought on by stress, sleep deprivation, day-time drowsiness, alcohol, and fever.
While it may seem funny that someone could clean their entire house in their sleep, sleepwalking can be a terrifying, and sometimes dangerous condition. Sleepwalking occurs during the “deep sleep”, or non-REM sleep, and it involves the individual walking or performing complex tasks while sleeping. The tasks can be anything from wandering around the house to getting in the car and driving long distances.
Sleepwalking is more common in children than adults, as well as those that are sleep deprived. The sleeper will likely not remember the dream, and they can be difficult to wake up. Contrary to popular belief, you may wake up a sleepwalker, and it may be crucial to do so to prevent injury.
Acting Out Dreams (REM Sleep Behaviour Disorder)
Many of us feel as though we’re “living” our dreams, but muscle paralysis stops us from physically moving. A person with REM Sleep Behaviour Disorder lacks the muscle paralysis, allowing them to act out dramatic or violent dreams while they’re in the REM stage of sleep. Some will engage in sleep talking, shouting, hitting or punching.
Sleep behavior disorder is usually triggered by heavy physical activity, febrile illness, sleep deprivation, excessive caffeine, hypnotics, and emotional stress . This disorder can be dangerous for both the sleeper and their bed partner, as flying limbs can cause injury.
Anyone who has had sleep paralysis will admit that it’s a terrifying experience, even for the bravest of dreamers. Normally, when you sleep your brain signals to your muscles to relax and be still. During sleep paralysis, your brain sends the message to your muscles while you are still awake, making you unable to physically move. It can occur when you are just falling asleep, or just waking up. While you are still able to breathe properly, you may be unable to speak or move your body, and it can last for seconds or minutes. Some people have even been known to hallucinate, thinking that someone is in the room with them.
Sleep paralysis can occur once in your life, or multiple times. It is first seen in the teenage years and then becomes more prevalent in the 20s and 30s. Sleep paralysis tends to be genetic, and you are more likely to experience it if you have a relative that does.
Lack of sleep, mental strain, sleeping on your back, and a constant change in sleep schedule can all making sleep paralysis more likely.
In the history of Western medicine, sleep paralysis has been documented for at least 300 years. It was once believed that during sleep paralysis, the devil would sit on the chest of the sleeper, making them unable to move their limbs. In the year 1689, Dutch physician Isbrand Van Diemerbroeck wrote a report titled ‘Of the Night-mare’ describing his patient’s symptoms:
“…in the night time, when she was composing herself to sleep, sometimes she believed the devil lay upon her and held her down, sometimes that she was choked by a great dog or thief lying upon her breast, so that she could hardly speak or breath and when she endeavoured to throw off the burthen, she was not able to stir her members.”.
It’s fairly common to see monsters within your dreams, but with a hypnogogic hallucination, you may believe that these monsters are real. They are mainly visual, but may also involve your senses of sound, touch, taste, and smell. These scary visuals occur when you are about to fall asleep or are waking up. They are reported in as many as one-third of people, most commonly in teens and young adults, and occur slightly more often in females than in males.
Sleep-related hallucinations can occur in as many as 25% of people, as opposed to under 5% for nonsleep related hallucinations. They can be a direct result of alcohol or drug use, insomnia, anxiety or stress.
Many children have a fear of the dark, and with all of the potential things that can happen to their mind and body in their sleep, it’s no wonder! While many of these sleep-related behaviors don’t interrupt the sleep cycle, it is important to talk to your doctor if you or your family members are experiencing any side-effects. Nighttime should be an opportunity for us all to re-charge our batteries and get some rest. Sleep should be relished, not feared.
 National Sleep Foundation. Sleep Disorders Problems. Retrieved on September 20, 2017 from https://sleepfoundation.org/sleep-disorders-problems/abnormal-sleep-behaviors/
 Psychology Today Associates. (August 5, 2017). Nightmares. Retrieved on September 20, 2017 from https://www.psychologytoday.com/conditions/nightmares
 F. Gokben Hizli and Nevzat Tarhan. (March 4, 2012). Parasomnias – Sleep Disorder Book. Retrieved on September 20, 2017 from https://www.sleepassociation.org/
 Carla MacKinnon. Sleep Paralysis Project: Culture and History. Retrieved on September 20, 2017 from http://www.thesleepparalysisproject.org/about-sleep-paralysis/culture-and-history/