3.5 years old sleeping arrangements

My son has been sleeping independently for the past 1.5 years. Recently he will sneak out of his room and totally refused to sleep in his own room without me or he will want to sleep in my room. Its so stressful as it is ny 'me time' once my kids entered their room for the night. Now its a battle every night to get him to his own bed. :( advise pls.