Question:
Is there a problem of Yichud for a brother(over Bar Mitzva) and sister(over Bat Mitzva) to travel with one man who is driving them in middle of the night in a place where there aren’t cars on the roads, and there aren’t people on the streets, and it’s possible that the brother will fall asleep at some point
Answer:
If the brother might fall asleep while they are traveling, then he can’t be considered a shomer, and it would be yichud. There are certain relatives that would be a shomer even when they are sleeping, such as a husband and wife a husband, or a wife, a man with his mother in law and her daughter-in-law, however a brother and sister are not included in this.
Sources:
Rema E:H 22-5, Meiri Kiddushin 81, Pischei Teshuva E:H 22-2, Toras Hayichud5-20, 21.
