Did you know…
Dreaming only happens during a part of your sleep cycle called REM sleep. While in this stage of sleep, you’re actually in a state of temporary paralysis. Because our dreams often involve some kind of movement, this paralysis is meant to be protective and to keep you from actually trying to fly or jump off a cliff or something. REM sleep is also very important for learning, which is why infants experience shorter sleep cycles with more period of REM sleep than adults.
So what about people who walk or talk in their sleep?
Doing things like walking or talking while asleep, or having night terrors are considered to be paranormal sleep activity, and they only occur in NREM (or non-REM) sleep. This is why people who do these things never have any memory of doing it. Unlike REM sleep, your body is not in a state of paralysis during NREM sleep, and it’s therefore possible to move around, even if it’s not remembered.
What’s the difference in a nightmare and a night terror?
Nightmares happen during REM sleep, when the brain is more active. Your body is in a state of paralysis, but you can remember things that happen during this stage.
Night terrors happen during NREM sleep and typically involve violently screaming, thrashing around, etc. But because it happens during the NREM cycle people who experience this never remember what they were dreaming about.