Q. Regarding one taking a sleeping pill during late afternoon Shabbos, for having effect after Shabbos. It is needed to be taken early, since otherwise it will affect that person in the morning after and will not be able to wake up on time. Is that permitted?
A. As we wrote on question 3220 above Horav Shlomo Miller's Shlit'a opinion is that one is permitted to take a sleeping pill during Shabbos when needed. (See also Rechev Eish 130 for a similar p'sak from the Rov).
In this case, one may also take the sleeping pill during Shabbos, even if its effect is intended for after Shabbos. This is similar to the Rov's permit of taking a fasting pill in Shabbos, for help in fasting on a Taanis after Shabbos
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a