Q. Dear Rov. As is well known one of the actions mentioned that causes forgetfulness of Torah learning is using one’s clothes as a pillow and laying one’s head on them. Why then do people commonly even in a Beis Medresh when seating next to a Shtender or table, lay their heads over their arms and fall asleep for a while, when actually laying their heads over the sleeves of their jackets or shirts?
A. Indeed the above is one of five actions that promote forgetfulness of Torah learning mentioned by Talmud Horios (13b), and is also mentioned by Mishna Berura (2: 2).
Sefer Zikaron maintains that sleeping over the clothes that one is wearing, is not related to the above, since those clothes are considered as part of himself and not as sleeping over “clothes.”
Horav Shlomo Miller’s Shlit’a opinion is similar.
Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a.