Question: How come when we sleep and get scared in our dream, we wake up?

Alex Reid answered on 7 Nov 2018:

Thanks for the question. The type of sleep most associated with dreaming is called Rapid Eye Movement (REM) sleep, and this type of sleep is also most associated with processing and consolidating emotional memories (in particular negative ones as they can contain important information). This might be why, when you write them down, many dreams tend to feature a lot of negative experiences compared to waking life. So, alongside what Warren has rightly said, two other factors may also be in play. Firstly, just by the virtue of waking up at the point when you are dreaming, negative dreams might also be at their most vivid and memorable, and as such you might infer (correctly or incorrectly) that it was the nasty dream content that woke you up. Secondly, you get more REM sleep right at the end of the night, just before you naturally wake up and sleep is becoming increasingly shallow. These two things might contribute to the likelihood of waking up during (or after) a negative dream and remembering it. To be clear these are not the only answers to your question, and the point Warren mentioned above is a good one.