Sleeping Alone at Night

The Aish Rabbi Replies

Potentially. The Talmud (Shabbat 151a) writes that one should not sleep alone for Kabbalistic reasons. This applies if you live alone. Even if there are other people in the house but you have your own room, you should keep your door unlocked (unless that causes a yichud (seclusion) issue with a woman in the house). However, if light enters your room, the issue does not apply.

(Sources: Eishel Avraham O.C. 239; Mishna Berurah 239:8, Sha’ar HaTziyun 17; B’Tzel HaChochma IV 76.)