Schumacher, 45, slammed his head on a rock while skiing off-piste in the French Alps resort of Meribel on December 29.
The retired racing driver, the most successful Formula One champion of all time, has been in a stable but critical condition for more than four weeks in a hospital in the eastern French city of Grenoble.
"Michael's sedation is being reduced in order to allow the start of the waking-up process, which may take (a) long time," his agent, Sabine Kehm, said in a statement.
The accident prompted an outpouring of concern for the German racing driver, who has undergone two operations while in hospital.
Investigators have been trying to determine the speed at which Schumacher was skiing when he hit the rock off-piste. French police have said the slope was properly marked.
(Reporting by Alexandria Sage; Editing by James Regan and Andrew Heavens)
