Causes of sleep paralysis
Sleep paralysis happens when parts of rapid eye movement (REM) sleep occur while you're awake.
REM is a stage of sleep when the brain is very active and dreams often occur. The body is unable to move, apart from the eyes and muscles used in breathing, possibly to stop you acting out your dreams and hurting yourself.
It's not clear why REM sleep can sometimes occur while you're awake, but it has been associated with:
- not getting enough sleep (sleep deprivation or insomnia)
- irregular sleeping patterns – for example, because of shift work or jet lag
- narcolepsy – a long-term condition that causes a person to suddenly fall asleep at inappropriate times
- a family history of sleep paralysis
- sleeping on your back
In many cases, sleep paralysis is a one-off or very occasional event that occurs in someone who is otherwise healthy.