The medical term for the inability to move one's body while sleeping is called sleep paralysis, also known as somnambulism, which is a common sleep disorder that occurs during the rapid eye movement (REM) phase of sleep. During REM sleep, the body's muscles become relaxed and weakened, and the brain remains active in dream formation. If the brain gradually exits the dream state, but the muscles remain paralyzed, resulting in a state where the brain is awake but the body is not, this can lead to the phenomenon known as "sleep paralysis," commonly referred to as the feeling of being "pinned down" by an unseen force.
Human sleep is divided into REM (rapid eye movement) and NREM (non-rapid eye movement) stages, which alternate throughout the night. When a person falls asleep, they initially go through the various stages of NREM sleep before entering REM sleep. This cycle repeats multiple times. During REM sleep, which is the stage of deep sleep where dreaming occurs, the brain's activity is similar to that of wakefulness, but the body's other systems function differently. The paralysis of the body during this stage ensures that we do not act out our dreams and potentially harm ourselves or others.
If a person suddenly awakens from a dream during REM sleep, the brain may not have time to reconnect with the body, resulting in a situation where the brain is conscious but the muscles remain in a static state. This can lead to the experience of "sleep paralysis," where the body does not respond to the brain's commands. The main groups of people who experience the inability to move their bodies while sleeping include:
1) Individuals with specific medical conditions, such as those with narcolepsy, who are more prone to experiencing sleep paralysis.
2) People who are under high stress or have irregular sleep schedules. Factors such as fatigue, staying up late, insomnia, and anxiety can all contribute to the development of sleep paralysis.
3) People with poor sleeping habits or positions. A study from 2002 found that 58% of sleep paralysis episodes were reported by individuals who were sleeping on their backs (8% were prone, and 17% were sleeping on their sides). Habits such as sleeping with one's hands pressed against the chest, covering the head with a blanket, or sleeping on the stomach can restrict breathing and circulation, leading to the experience of sleep paralysis.
4) Individuals with sleep disorders such as hypersomnia or sleep apnea syndrome. If a person experiences daytime drowsiness, sleep paralysis, or hallucinations before falling asleep, they may be suffering from hypersomnia.
