A truck cab, comprising: a truck cab housing comprising a truck cab interior; a convertible seat assembly (108, 108') comprising: a base member (110, 110') having a substantially flat upper surface (112, 112'), the base member (110, 110') fixed with respect to the truck cab interior; a back member (120, 120') having a first side (122, 122') with a substantially flat surface and a second side (124, 124'), the back member (120, 120') rotatably coupled to the base member (110, 110') for movement between a sleeping configuration and a seating configuration; and a seat member (128, 128') coupled to the second side (124, 124') of the back member (120, 120'); wherein the substantially flat surface of the first side (122, 122') of the back member (120, 120') in the sleeping configuration and the substantially flat upper surface (112, 112') of the base member (110, 110') form a substantially flat horizontal sleeping surface (130, 130'), wherein the seat member (128, 128') in the seating configuration forms a seating region (132, 132'), and characterised in that the truck cab interior further comprises a dashboard support member supporting the back member (120, 120') in the sleeping configuration. a truck cab housing comprising a truck cab interior; a convertible seat assembly (108, 108') comprising: a base member (110, 110') having a substantially flat upper surface (112, 112'), the base member (110, 110') fixed with respect to the truck cab interior; a back member (120, 120') having a first side (122, 122') with a substantially flat surface and a second side (124, 124'), the back member (120, 120') rotatably coupled to the base member (110, 110') for movement between a sleeping configuration and a seating configuration; and a seat member (128, 128') coupled to the second side (124, 124') of the back member (120, 120'); wherein the substantially flat surface of the first side (122, 122') of the back member (120, 120') in the sleeping configuration and the substantially flat upper surface (112, 112') of the base member (110, 110') form a substantially flat horizontal sleeping surface (130, 130'), wherein the seat member (128, 128') in the seating configuration forms a seating region (132, 132'), and a base member (110, 110') having a substantially flat upper surface (112, 112'), the base member (110, 110') fixed with respect to the truck cab interior; a back member (120, 120') having a first side (122, 122') with a substantially flat surface and a second side (124, 124'), the back member (120, 120') rotatably coupled to the base member (110, 110') for movement between a sleeping configuration and a seating configuration; and a seat member (128, 128') coupled to the second side (124, 124') of the back member (120, 120'); wherein the substantially flat surface of the first side (122, 122') of the back member (120, 120') in the sleeping configuration and the substantially flat upper surface (112, 112') of the base member (110, 110') form a substantially flat horizontal sleeping surface (130, 130'), wherein the seat member (128, 128') in the seating configuration forms a seating region (132, 132'), and characterised in that the truck cab interior further comprises a dashboard support member supporting the back member (120, 120') in the sleeping configuration.