Have you ever woken up and felt stuck to your bed, unable to move your limbs? There seemed to be someone in the room, watching you, advancing toward you menacingly, sometimes even drawing the sheets away. You couldn’t breathe! Someone was sitting on your chest! And though you wanted to scream, you couldn’t even whisper. You just lay there, terrified, waiting for the unimaginable to happen. Then you were suddenly released or you woke up or even drifted back to sleep.
No, this is not a visit from malevolent spirits or evil aliens. The medical term for this phenomenon is sleep paralysis.
Sleep paralysis is medically defined as a temporary inability to move, speak, or react during waking up or falling asleep despite being in a state of consciousness. It is a sleep disorder that falls under the category of parasomnia or unusual behavior during sleep. Based on the time when it occurs, it can be categorized as:
If sleep paralysis occurs independently of sleep disorders like narcolepsy (a chronic brain disorder where the brain has poor control on the sleep-wake cycle) or other medical conditions, it is called isolated sleep paralysis. If it occurs repeatedly, it is known as recurrent isolated sleep paralysis.
You aren’t the only one suffering from sleep paralysis. A study on 36,533 participants found that
experienced at least one episode of sleep paralysis.
The study also found that Asians (38.7%), especially Asian students, were most likely to experience sleep paralysis, and women (18.9%) were more likely victims of recurrent sleep paralysis than men (15.9%).
Though sleep paralysis begins mostly during adolescence, there have been cases of onset in childhood or middle age.
In most people, isolated sleep paralysis episodes occur less than once a year and the episodes last for a few seconds to minutes. But in those with recurrent sleep paralysis, the episodes are more frequent and last for several minutes, and the phenomenon might continue for months. As per the International Classification of Sleep Disorders (ICSD), it can be thus categorized on the basis of frequency and duration:4
As you begin to fall asleep, your body starts relaxing, taking you through the 4 stages of the non-rapid eye movement (NREM) phase, eventually lulling you into deep sleep. After 80 to 100 minutes, you move into the rapid eye movement (REM) phase, where you start dreaming vividly. You keep repeating this NREM/REM cycle till you wake up.
During REM, your brain releases chemicals called glycine and GABA to paralyze your muscles,so that you don’t physically act out the dreams. This state is called atonia. Your brain is highly active; your breathing is irregular; and your heart rate and blood pressure are high.
Hypnopompic sleep paralysis occurs when you wake up before the REM stage is complete. This is due to an overlap in sleep states or an overlap between wakefulness and sleep. This can happen if:
You have woken up, but your brain has not released the muscles and is still in the dream state. Hence the bizarre hallucinations and experiences that often accompany sleep paralysis.
There are usually 3 kinds of visual hallucinations, also called hypnagogic hallucinations, that accompany sleep paralysis.
You feel that there is a threatening presence in the room. Some people even report seeing shapes, animals, or tall, dark, formless bodies.A 1999 study claims that this is due to a hypervigilant state initiated in the midbrain. Hypervigilance is a state where your senses are highly enhanced to enable you to detect the slightest threat. Such heightened sensitivity also brings along anxiety, which explains the fear associated with such experiences during sleep paralysis.
You feel that someone is sitting on your chest and suffocating you.Breathing is anyway shallow and rapid during REM. And, if you are lying on your back, the upper airway muscles are also relaxed, reducing the airflow. So, as you struggle to breathe deeply and fail, panic sets in, and you interpret the situation as someone sitting on your chest.
The University of Waterloo conducts an interesting survey on the experiences people have during sleep paralysis. In it, some people have reported that they have been able to leave their bodies and float in the air or fly about.How does this happen? To put it simply, several mechanisms in your body coordinate to give it information about its movement and position. During sleep paralysis, some of these get activated, but in the absence of corresponding movement, your body mistakenly interprets this as floating or flying.
Patients of narcolepsy, about 17 to 40%, are the most usual victims of sleep paralysis. Obstructive sleep apnea, a condition where the throat muscles relax during sleep and obstruct airflow, is also a risk factor.If you suffer from any type of sleep disturbance such as caused by restless leg syndrome or even nighttime leg cramps, sleep paralysis is likely.
Sleeping and waking up follows a 24-hour pattern, the circadian rhythm. When this pattern is disrupted, whether because of alcohol and drug abuse, shift work, inconsistent sleep timings, or lack of sleep, the chances of sleep paralysis go up.
Sleep paralysis also runs in the family. A study with siblings and identical and fraternal twins found that genes could be held responsible for 53% of the occurrences of sleep paralysis. Identical twins have similar risks of experiencing the condition. And in some cases, sleep paralysis can occur even when the faulty gene is passed on by only one parent.
If you have experienced traumatic incidents and you are suffering from post-traumatic stress disorder, you are more likely to experience sleep paralysis.
If you have a history of panic disorder, anxiety disorder, social anxiety, and a negative self-image, you are likely to hallucinate about an ominous presence – that of an intruder – during sleep paralysis. These are often also effects of sleep paralysis itself and the process could be cyclical.Severe depression is also linked to sleep paralysis.People with bipolar disorder also suffer from sleep disturbances and parasomnias.
Most incidences of sleep paralysis have been reported in cases where the person was lying on his or her back. The University of Waterloo survey results claim that about 60% of the episodes occur when one is lying in the supine position.
Since this condition is triggered naturally by the body and is generally not harmful (unless it is a symptom of narcolepsy or is linked with other mental disorders), there is no medication. If you have recurrent episodes and are traumatized by the experience, visit your doctor. The doctor may prescribe sleeping pills and low doses of antidepressants to help you sleep better. But rather than relying on medication that will have side effects, here’s what you can do: