system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When sleeping why do some people move so much like kids, but others can stay in the same position for hours?
gpt
The simplest answer is that the people who move around lots usually have one or more of the upwards of 80 sleep disorders. The people without sleep problems are the ones sleeping still.

Source: 15 years working in sleep medicine.