A sleep apparatus includes: a mat main body portion configured to support a user in a supine state; and a tilting mechanism that, at the mat main body portion, periodically tilts a body of a user left and right, by alternately raising a right side supporting portion, which includes portions supporting a right-side hipbone and a right-side shoulder blade of a user, and a left side supporting portion, which includes portions supporting a left-side hipbone and a left-side shoulder blade of a user.