When we practice yoga we stretch our spine; therefore, we don’t “srink” and we can keep the same height throughout our life. I don’t think we can grow though, but it can happen that a person who has already srunk, by stretching his spine can recuperate his original height.
Meditation is like a “bath” for the brain and it can clear worries, anxiety and other unnecesary issues that makes us tired. Therefore, if you meditate every day you will have more energy and feel rejuvenated, which can lead to less hours of sleep. However, we don;t want to substitute sleep because is an important function of the body that help us recover and regenerate.