Use the up and down arrow keys. FINALLY, there are *no* size issues, because the sizes of the beds are based on one constraint, not just on themselves. Thanks to @Bow_II for the suggestion! Remix and add yourself in/at one of the beds. Please! For best results, don't use a new sprite. I provided loop scripts, so you can make a multiple-costume animation.
Credit to EVERYONE in the ENTIRE COMMUNITY!! Sample here: http://scratch.mit.edu/projects/13405217