A six-month jail term for a former Stanford University swimmer convicted of sexually assaulting an unconscious woman is being decried as a slap on the wrist.

A California judge sentenced 20-year-old Brock Turner to six months in county jail and three years' probation after the woman who was assaulted read the court an emotional statement that has gone viral.

She described how the attack left her "closed off, angry, self-deprecating, tired, irritable, empty."

Prosecutors had asked for a six-year prison sentence.

Santa Clara County Superior Court Judge Aaron Persky said in handing down the punishment that a longer sentence would have a "severe impact" on Turner.

Turner is a three-time All-American high school swimmer from Dayton, Ohio. He withdrew from Stanford after his January 2015 arrest.