236. Reciting Shema in Any Position

Kriyas Shema 2:2

One may recite Shema however he is: standing, walking, reclining, or riding on an animal. One may not recite Shema lying face down on the ground or flat on his back facing upward. One may recite it while lying on his side. Someone who cannot roll over onto his side because he is very large or sick should lean slightly on his side in order to recite Shema.

Kriyas Shema 2:3

A person who is walking must stop to recite the first verse of Shema; the rest may be recited while walking. If a person is asleep, he should be repeatedly awoken until he recites the first verse. After that, if sleep overtakes him, he need not be disturbed.