A sleep apparatus (10, 80), comprising: a mat main body portion configured to support a user in a supine state; a tilting mechanism (70L, 70R, 72L, 72R, 81) configured to, at the mat main body portion, periodically tilt a body of a user left and right, by alternately raising a right side supporting portion, which includes portions configured to support a right-side hipbone and a right-side shoulder blade of a user, and a left side supporting portion, which includes portions configured to support a left-side hipbone and a left-side shoulder blade of a user, wherein: the mat main body portion includes a central supporting portion configured to support buttocks and thigh regions of a user, an upper side supporting portion that is rotatably connected to one end side of the central supporting portion and configured to support a back region and head portion of a user, and a lower side supporting portion that is rotatably connected to another end side of the central supporting portion and configured to support leg portions of a user, and the mat main body portion is configured to alternately switch between a seat state and a bed state, by the upper side supporting portion and the lower side supporting portion rotating with respect to the central supporting portion; wherein it further comprises a plurality of supporting airbags (68, 69) provided at the mat main body portion, wherein: internal air pressures of the supporting airbags (68, 69) are respectively adjustable, the supporting airbags (68, 69) are disposed along a direction heading from the upper side supporting portion toward the lower side supporting portion, and characterized in that the internal air pressures of the supporting airbags (68, 69) are adjusted such that the internal air pressures of the supporting airbags (68, 69) at the central supporting portion are higher in the bed state than in the seat state. a mat main body portion configured to support a user in a supine state; a tilting mechanism (70L, 70R, 72L, 72R, 81) configured to, at the mat main body portion, periodically tilt a body of a user left and right, by alternately raising a right side supporting portion, which includes portions configured to support a right-side hipbone and a right-side shoulder blade of a user, and a left side supporting portion, which includes portions configured to support a left-side hipbone and a left-side shoulder blade of a user, wherein: the mat main body portion includes a central supporting portion configured to support buttocks and thigh regions of a user, an upper side supporting portion that is rotatably connected to one end side of the central supporting portion and configured to support a back region and head portion of a user, and a lower side supporting portion that is rotatably connected to another end side of the central supporting portion and configured to support leg portions of a user, and the mat main body portion is configured to alternately switch between a seat state and a bed state, by the upper side supporting portion and the lower side supporting portion rotating with respect to the central supporting portion; wherein it further comprises a plurality of supporting airbags (68, 69) provided at the mat main body portion, wherein: internal air pressures of the supporting airbags (68, 69) are respectively adjustable, the supporting airbags (68, 69) are disposed along a direction heading from the upper side supporting portion toward the lower side supporting portion, and characterized in that the internal air pressures of the supporting airbags (68, 69) are adjusted such that the internal air pressures of the supporting airbags (68, 69) at the central supporting portion are higher in the bed state than in the seat state. the mat main body portion includes a central supporting portion configured to support buttocks and thigh regions of a user, an upper side supporting portion that is rotatably connected to one end side of the central supporting portion and configured to support a back region and head portion of a user, and a lower side supporting portion that is rotatably connected to another end side of the central supporting portion and configured to support leg portions of a user, and the mat main body portion is configured to alternately switch between a seat state and a bed state, by the upper side supporting portion and the lower side supporting portion rotating with respect to the central supporting portion; wherein it further comprises a plurality of supporting airbags (68, 69) provided at the mat main body portion, wherein: internal air pressures of the supporting airbags (68, 69) are respectively adjustable, the supporting airbags (68, 69) are disposed along a direction heading from the upper side supporting portion toward the lower side supporting portion, and characterized in that the internal air pressures of the supporting airbags (68, 69) are adjusted such that the internal air pressures of the supporting airbags (68, 69) at the central supporting portion are higher in the bed state than in the seat state. internal air pressures of the supporting airbags (68, 69) are respectively adjustable, the supporting airbags (68, 69) are disposed along a direction heading from the upper side supporting portion toward the lower side supporting portion, and characterized in that the internal air pressures of the supporting airbags (68, 69) are adjusted such that the internal air pressures of the supporting airbags (68, 69) at the central supporting portion are higher in the bed state than in the seat state.