Q. If someone was staying up the learn the whole night of Shavuos, but then realized that he is too tired and went to sleep in his bed for an hour, when he comes back to continue learning, does he have to say Birchas Hatorah?
How about if someone went to sleep in his bed and could not fall asleep. Then decided to go to shul and learn the rest of the night does he have to make the brocho?

A. Poskim rule that one does not recite Birchas Hatorah in the first case, since his intention was only to sleep enough to be able to return to his all-night learning. Therefore there was no “hesech hada’as” or disruption of intent. (Kaf Hachaim 46: 27, et. al.). Horav Shlomo Miller Shlit’a pointed out that at daybreak he should recite the Torah blessing to continue learning until the beginning of davening.
(See Aruch Hashulchan 47: 23. in regards to sleeping before or after midnight).
Nitey Gavriel (Shavuos 20:10 – 11 p. 135) quotes Teshuvas Harosh (4: 1) who maintains that in the second case, although he went to bed with the intention of falling asleep and not learning anymore that night, since he did not actually fall asleep, he was also not masiach da’as. Therefore, there is no need to recite the brocho.
Horav Shlomo Miller’s Shlit’a opinion is that in cases where there is some doubt of having to recite the Torah blessing, which according to many Poskim is of Biblical origin, one may recite it without pronouncing Hashem’s name. He would thus comply at least on the Biblical level, the requirement of Birchas Hatorah.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a