You wake up, open your eyes, and try to get out of bed. But you can’t move. Panic sweeps over you, and you are unable to cry out for help. Suddenly, you feel a heavy weight on your chest and you see dark figures surround your bed. A few seconds later, it’s finally over and you are able to move.
Sound familiar? If so, you have experienced sleep paralysis (SP). SP is another mysterious parasomnia sleep disorder. It is characterized by an inability to move upon awakening, but vision, touch, and hearing are still in tact. Here’s how this happens. When we enter REM sleep, our body enters a state of muscle paralysis. If this does not happen, we would act out our dreams in our sleep. For many reasons, we do not want this to happen.* So, SP happens when you awake before the muscle paralysis has ended.
Approximately 30% of the population has experienced an episode of SP at least once. It is much more common in students, most likely due to the exaggerated sleepiness of this group. SP prevalence is also slightly higher in individuals with anxiety, PTSD, and narcolepsy. However, experiencing an episode of SP does NOT indicate an underlying pathology; many healthy people experience SP.
Episodes of SP also tend to be very frightening. In a student sample, 90% of participants stated that their episode of SP was frightening. One reason for this is the state of complete paralysis. Experiencing this for the first time, not knowing why you can’t move, can arouse great fear. Second, hallucinations are common during SP; sexual assault and intruders are common themes during these.
Different cultures throughout the world have given different meanings to these hallucinations. Some think it’s religious. Some think it’s witchcraft. Some think it’s demons. One new trend is people reporting getting abducted by space aliens.
In a study at Harvard, researchers interviewed and examined 10 people who reported alien abduction during an episode of SP. Below is an example of a report of one of the female “abductees.”
“Another female abductee was lying on her back when she woke up in the middle of the night. She was completely paralyzed, and felt electrical vibrations throughout her body. She was sweating, struggling to breathe, and felt her heart pounding in terror. When she opened her eyes, she saw an insect- like alien being on top of her bed.”
Psychiatric interviews revealed very little psychopathology; several of the participants met the requirements for anxiety related disorders. However, compared to controls, they scored significantly higher on scales of dissociative experiences and magical thinking. Interestingly, three of the participants nearly met criteria for PTSD related to the space alien abduction.
Researchers went a step further in examining PTSD related to their “abduction.” They created a script of the abduction, which “replays” the event to the individual. They then measured physiological responses (i.e. heart rate and skin conductance) of the individual upon hearing the script. They then compared these responses to a large study that employed similar methods on Vietnam veterans diagnosed with PTSD. Amazingly, the abductees had larger physiologic responses than the Vietnam veterans.
This study was not to support the idea of extra terrestrial life. It is interesting, however, that many people report experiences like this. It is also quite fascinating what our mind can do while transitioning between the different sleep stages.
*This is called REM Behavior Disorder (this will be detailed in a future post!).
McNally, R. J., & Clancy, S. A. (2005). Sleep paralysis, sexual abuse, and space alien abduction. Transcultural psychiatry, 42(1), 113-122.
Sharpless, B. A., & Barber, J. P. (2011). Lifetime prevalence rates of sleep paralysis: a systematic review. Sleep medicine reviews, 15(5), 311-315.