in the database make your main hero have the graphic of the sleeping character.
Place your start position over the bed, or wherever he will be sleeping.
In the events there should be a command call "Shake Screen"
use that and set the parameters (how long to shake and how intense)
Use a wait command for how long it is going to shake, 15-25 frames should be enough, 40-50 frames if it is an earthquake. You need to sue the wait command so RMXP doesn't continue to run the rest of your event commands until the screen stops shaking. If you want your player to wake up while the screen is shaking, have the wait be less than what you set in the Shake Screen command.
now use the Change Actor Graphic event, it should be on the 3rd page of the events, and change it to the walking sprite of your character.
Now use the Control Self Switches event, and turn Switch A on.
Now hit "New event page" in your event, and on that blank page, set the precondition to Self Switch: A is ON.
Hit APPLY, OK, then test run it and see if it works!