Waking to the awful feeling that you’ve lost control of your limbs can be terrifying, but sleep paralysis is essential to keep you safe at night. When we dream during rapid eye movement (REM) sleep, our brains run through vivid simulations and try to send messages to our muscles. But two signalling chemicals, gammaaminobutyric acid (GABA) and glycine, stop messages reaching the motor neurons. This prevents us from acting out our dreams and harming ourselves and others, but sometimes the system can malfunction. The frightening experience of sleep paralysis happens when our brains enter this dream-like state when we’re still awake. It’s rare, but occurs more often if we’re over tired, have jet lag or work irregular shifts that mess with our body clocks.
The brain stops sending signals to the muscles when we dream