Your brain wakes while your body is still in REM muscle-lock - the mechanism that keeps you from acting out dreams running a few seconds late.
MedlinePlus notes episodes last seconds to a few minutes, end on their own, and are common. The vivid intruder or chest-pressure hallucination is the same mechanism, dream fragments bleeding into the room - not supernatural. Triggers: sleep deprivation, irregular schedules, back-sleeping, stress. The red flag that changes the picture is cataplexy - emotion-triggered weakness while awake - which with crushing daytime sleepiness points toward narcolepsy evaluation.
What to do
Common questions
Why do I get sleep paralysis?
Sleep paralysis is a timing glitch between two systems. During REM sleep - the dreaming stage - your brain paralyzes your voluntary muscles so you do not act out dreams; sleep paralysis is the moment your mind wakes up while that muscle-lock is still on, sometimes with vivid, often frightening dream-fragments bleeding into the room - the classic intruder or pressure-on-the-chest hallucination is the same mechanism, not a supernatural event. MedlinePlus notes episodes last from seconds to a few minutes and end on their own, and that it is common - many people have at least one episode. The triggers that raise the odds: sleep deprivation and irregular schedules, sleeping on your back, stress, and disrupted sleep from shift work or jet lag. It is benign - the red flag that changes the picture is cataplexy: sudden muscle weakness triggered by emotions while fully awake, which together with paralysis episodes and crushing daytime sleepiness points toward narcolepsy evaluation. Prevention is boring and effective: consistent sleep, enough of it, and side-sleeping. In the moment: focus on moving a small muscle - a toe or finger - and breathing slowly. Pymander, a free AI doctor available 24/7 by text, can help you sort pattern from one-off.