The Neuroscience Behind Sleep Paralysis

Sleep paralysis happens during the most dream-filled portion of sleep. The brain regains consciousness while the body experiences voluntary muscle paralysis associated with REM (rapid eye movement) sleep. Unfortunately, this condition causes the dream world and the real world to overlap and can produce terrifying illusions and sensations.

Don’t worry—sleep paralysis doesn’t last longer than a few minutes. While knowing the episode won’t last for long, knowing what is happening to you and how it’s happening can help you overcome the nightmare better.

This article will discuss what sleep paralysis is, different sleep stages and their connection to sleep paralysis, and how abnormal sleep disruptions can cause the condition to occur. We will also explore the different sensations people feel during sleep paralysis and how to prevent episodes.

What Is Sleep Paralysis?

Recurrent isolated sleep paralysis goes by a few names: sleep atonia, sleep palsy, or cataplexy. It’s a parasomnia condition where your mind becomes conscious while your body remains in a state of muscle paralysis induced by REM sleep. It’s a commonly-known sleep disorder that affects 8 percent of the general population.

Sleep paralysis is accompanied by pressure on the chest and auditory, visual, and olfactory hallucinations. It’s caused by stress, sleep deprivation, fatigue, traumas, panic disorders, and sleep disorders such as sleep apnea, insomnia, and narcolepsy.

The Chemistry of Sleep

When you go to sleep, several chemical and physical changes take place in the body; your brain stores the day’s information in long term memory, and your body undergoes cellular damage repair. These chemical and physical changes happen during a sleep cycle.

If your sleep lasts between 6 and 9 hours, you’ll experience between 4 and 5 sleep cycles—each sleep cycle is made of 4 stages: NREM and REM sleep.

NREM (non-rapid eye movement) sleep makes up three of the four sleep stages.

• NREM stage 1: This sleep stage takes place a few minutes after you’ve fallen asleep and lasts 5 to 10 minutes. You’re easily woken, and your eye movement slows. Your body experiences muscle relaxation, although muscle spasms are normal in this stage.

• NREM stage 2: During this stage of sleep, your body is preparing for deep sleep. You’re still easy to wake, but your heart rate slows and your body temperature drops. Your breathing will slow down.

• NREM stage 3: This stage is known as deep sleep. If someone manages to wake you, you’ll be tired and disoriented. Your body is completely relaxed, and there is no eye movement. Your blood pressure falls, and your body temperature drops even more.

“REM sleep is the last sleep stage where cellular regeneration happens and the brain repairs itself, cleans out any bacteria or viruses that might have entered from the day, regenerates and stores information from the day’s events. Proper REM sleep is a very important key to staying healthy,” says Shawna Robins, CEO of Kaia Health and Wellness, sleep expert and best-selling Amazon author of Powerful Sleep – Rest Deeply, Repair Your Brain and Restore Your Health. REM sleep can last between 5 and 45 minutes long, and each REM sleep stage lasts longer than the last. Collectively, you’ll want to get 90 minutes of REM sleep in a single night to feel refreshed in the morning. (A healthy adult will have 90 to 110 minutes of REM sleep per night.)

During REM, your brain is as active as if you were awake, which is why you dream. Your heart rate and breathing quicken, and your eye movement becomes rapid.

During REM, the part of the front brain that controls your ability to plan and think logically turns off, which is why dreams seem real. To prevent us from acting out dreams and potential injuries, gamma-aminobutyric acid (GABA) and glycine neurotransmitters stop communicating with the rest of the body by switching off parts of the brainstem, causing temporary paralysis.

If sleep is disrupted or you’re experiencing high levels of stress, you can become conscious during REM sleep. Becoming conscious of your surroundings during REM sleep can cause the real world and dreamworld to overlap and produce hypnopompic hallucinations.

Sensations of Sleep Paralysis

There are three primary sensations people feel when experiencing sleep paralysis: incubus, the intruder, and vestibular motor sensation. Not everyone feels all three sensations.

Incubus

The incubus sensation leaves the conscious person feeling as though something is sitting on their chest, finding it hard to breathe.

Sleep paralysis can only happen if the body remains in REM sleep paralysis, where the breathing patterns are short and quick, which gives the sensation of difficulty breathing and pressure on the chest.

Intruder and Incubus

The intruder sensation causes the sleeper to feel or see a presence in the room with them. Often the intruder takes the form of a shadow or human-like creature lurking in the dark. The intruder’s intent varies depending on the sleeper’s imagination. Sometimes the figure chokes the sleeper or makes it difficult to breathe by sitting on their chest.

Neurologists V.S. Ramachandran and Baland Jalal explained the intruder during episodes of sleep paralysis are due to temporoparietal junction activity disruption. The temporoparietal junction is responsible for developing a “body image” and gives you the ability to distinguish between your body and everything else. When temporoparietal junction activity is disrupted, a hallucination of your body shape projects in front of you. Victims often mistake the figure as a ghost or supernatural being.

Upon “seeing” the intruder, the brain attributes the symptoms of sleep atonia—chest pressure, rapid breathing, and sensation of suffocating— to the uninvited presence. From there, the memory and narrative regions of your brain can evolve the hallucination into realistic shapes.

Vestibular Motor Sensation

The vestibular motor sensation is an out of body experience where the person feels they are floating above their body. It’s an eerie experience some cultures refer to as an astral projection or the soul temporarily leaving the body.

The out of body sensation stems from activity disruption of the temporoparietal junction. Similar to the intruder sensation, the sleeper projects their body shape in front of them—however, they can only view themselves in the third-person from the projected shape.

Sleep Paralysis Prevention

Sleep paralysis is often a symptom of a larger problem, such as sleep deprivation, stress, or a panic disorder. Unfortunately, there are no treatments for sleep atonia, but you can take preventative measures to decrease your risk of a sleep paralysis episode.

Try limiting naps to under 90 minutes. Even better, eliminate naps. Sleep specialist Clete Kushida, MD, Ph.D., has said nappers are more prone to sleep atonia than those who don’t nap.

Get a consistent 7 to 9 hours of sleep each night. Sleep-deprived people have higher rates of sleep paralysis. We suggest sticking to a sleep schedule as it ensures you get a good amount of sleep and prevents you from staying up too late.

Try to avoid caffeine after lunch. Caffeine can linger in your bloodstream for up to 6 hours. It can keep you up and reduce sleep quality if it’s still in your body.

Practice good sleep hygiene. Poor sleep habits sometimes cause sleep disturbances. Keeping a bedtime routine, practicing relaxing bedtime rituals, and maintaining a clean sleep environment can improve your sleep quality.

• Refrain from eating or drinking liquids two 2-3 hours before bedtime as it can cause stomach issues and raise the risk of acid reflux.

• Ensure your bedding, pajamas, and room temperature are cool and comfortable.

• Use breathing techniques to relax before bed.

• Try exercising and getting sunlight exposure in the morning. If you exercise in the evening, try not to do so within 2 hours of bedtime. It’ll spike your adrenaline levels and make it harder for you to sleep.

• Consider sleeping on your side instead of your back, as sleeping on the back increases the chance of a sleep paralysis episode.

• Make sure your bedroom is dark. Block out sunlight with blackout curtains and turn off electronics to prevent sleep disruptions.

• Reduce blue light exposure in the evening 90 min before bedtime.

• Use earplugs to block out excessive noises.

• Encourage pets not to sleep on your bed or in your bedroom if they disturb you during the night.

Seek a physician’s help. Sleep paralysis is often caused by sleep disorders and poor mental health: insomnia, sleep apnea, sleep deprivation, depression, and anxiety disorders. If you have recurring episodes, we suggest looking for the guidance of a physician or counselor as the condition can impact your sleep quality.

Frequently Asked Questions

Can you die from sleep paralysis?

Sleep paralysis is scary, but it won’t kill you. If you experience sleep paralysis episodes on a regular basis, it can take a toll on your health, though. Sleep paralysis can impede a good night’s rest, and when these episodes happen nightly or even a few times weekly, it results in daytime fatigue and sleep deprivation. If left unaddressed, sleep deprivation can lead to a host of other issues.

How can I avoid sleep paralysis?

There’s no real way to completely avoid sleep paralysis, it can happen to anybody. However, if you’re prone to these episodes, we suggest finding ways to manage stress and fix your sleep schedule so you can enjoy better rest. Sleep paralysis can occur because of sleeplessness, stress, and a variety of other reasons, so finding ways to improve your overall health is a good way to prevent this unpleasant phenomenon.

Should I be worried about sleep paralysis?

If you don’t experience sleep paralysis, then you shouldn’t worry about it. That said, those who do experience sleep paralysis also have no reason to worry about it. Sleep paralysis is not life-threatening and cannot cause any physical harm. However, when frequent episodes impede sleep, it can lead to sleep deprivation.

What do you see during sleep paralysis?

Sleep paralysis is paradoxical because your mind is awake but your body is asleep. With that, though, you’re not completely awake and aware—you’re still halfway dreaming. Sleep paralysis is usually accompanied by hallucinations, and many see shadowy figures or figments from their dreams.

How long can sleep paralysis last?

Sleep paralysis usually only lasts a couple of seconds to a couple of minutes. Although, for those experiencing sleep paralysis, a couple of minutes can feel like a couple of hours because you’re still dreaming. If you have sleep paralysis (or you live with someone who experiences night terrors), we suggest not having anybody wake you (or waking another person). Doing so can cause even more disorientation and confusion.

Conclusion

An episode of sleep paralysis can cause you to see, feel, hear, and smell realistic hallucinations in a body still in REM sleep. We recommend people who experience sleep atonia frequently to seek a physician or counselor’s help, as sleep paralysis can lead to sleep deprivation, which can cause the condition to worsen and can lead to chronic health problems like obesity, heart disease, and Alzheimer’s.