The midfielder joined the Blades on a free transfer this summer after being released by Leicester City, but despite impressing the Blades fans has seen him out of the side since transfer-listed Nick Montgomery has produced some impressive performances.
Nalis now becomes the Blades 9th player to leave on loan this season and comes only a day after Chris Armstrong joined Blackpool. The 33 year old is expected to make his debut at home to Crystal Palace on Saturday.