Q. If one slept on Erev Shavuos afternoon a few hours but stayed up the rest of the Shavuos night learning can he recite Elokai Neshama?
A. Mishna Berura (46: 24) rules that one who was up a whole night, although Poskim disagree, he should avoid reciting Elokai Neshama and ask someone else who slept to say it for him while he listens.
If he slept during the day there are further reasons to be able to say it himself, if he can't fond someone else to be motzi or say it for him.
Since there are other doubts involved, Horav Shlomo Miller’s Shlit”a opinion is that it is better, if one can't find someone to recite it for him, to have in mind at the second brocho of the Amida, Mechaye Hamessim to comply with it.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a