Complex sentence: Children are usually required to be accompanied by an adult: since a certain level of peace and quietness is expected in the sauna area many establishments reserve special hours for children between 2 and 12 years old.
Split into simpler sentences: Children are usually required to be accompanied by an adult. Since a certain level of peace and quietness is expected in the sauna area many establishments reserve special hours for children between 2 and 12 years old.