I have heard that if one sleeps after eating fleishig, one need not wait six hours from eating fleishig, before eating milchig. Is that correct? If yes, what are the parameters, specifics, etc.? Thank you!
There is such an idea from some poskim, including R’ Eliyashiv zt”l, however most poskim disagree with this, and it is not the accepted practice. See sources.
See Daas Kedosihim that he only suggests it as a maybe, and even that he only says that it might be able to remove an hour or so, but only maybe. Also see MIkdash Me’at that he writes V’tzarich Iyun. Most poskim don’t hold of this idea they are : Noam Halacha 2-18, Kovetz Mbais Halevi 9 pg. 23, Teshuvos V’hanhagos 1-431, Avnei Yoshpe, Habayis Bkashruso pg. 36, Dole Umashke pg. 257 from R’ C. Kanievsky and R’ M. Gross shlit”a, R’ Y. Belski zt”l Piskei Halocho pg. 133. Regarding R’ Eliyashiv’s shita on this, it was only if the person slept for three hours and at night, see HIlchos Chag B’chag Shevuos ftnt. 118. Aside from this R’ Azriel Auerbach shlit”a, R’ Eliyashiv’s son in law (As quoted in Ohel Yackov)” It is known what my father in law said on this, but the minhag haolam is not to be leinient on this”, also see sefer Hakashrus 1-31, that this psak was not accepted as halacha lemaaseh.