ELI5 Dreams - why is it so hard to run in a dream?

Why do we forget our dreams in the mornings? Why is it so hard to run in our dreams? Why is it explained by proprioceptive feedback? How come kids can't control peeing in their sleep the way adults can? Does putting someone's hand in a warm bowl of water really make them wet the bed?   ... We explain like i'm five!   Sponsored by Goodnight Stories by Rebel Girls - check out Laurene Powell Jobs narrating the first episode from Season 4!   Thank you to the r/explainlikeimfive community as always and in particular the following users whose questions and comments formed the basis of this discussion: carderrrr, prob_dehydrated, bustamcthunderstick, noobsauce9001, 7thcourier, pkmkii, midafus, pavlovshumans & baeocystin. To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Send us an e-mail: [email protected]