Unfortunately it’s impossible to become fit while you sleep. What you can do however, is exercise while you lie down!
Lie down with your legs stretched. Now act as if 1 leg I longer and push it down.
Also, move your hip with it. Do the same for your other leg.
Do this exercise 10x for each leg. Then switch to the other leg.
Already feeling taller? Finished the exercise? Well done!
Watch out:
Exercising should be fun and it should make you move better. Does it hurt during the exercise or do you feel uncomfortable? Then tell this to your parents / caretakers and stop the exercise.