Disclosed herein is an air mattress (100) including at least two separate zones (102,103). A first and second groups of elongate, inflatable cells (U1,U2,L1,L2) are disposed alternately within each of the at least two separate zones (102,104). An air pump (106) is to supply pressurized air. At least two air distributors (108,114) are serially connected with the air pump (106) for respectively distributing the pressurized air to the at least two separate zones (102,104). Each air distributor (108,114) is operable to supply the pressurized air to the first (U1,U2) and second (L1,L2) groups of cells within each of the at least two separate zones (102,104). A pressure reducer (112) is serially connected between any adjacent two of the at least two distributors (108,114) for reducing the pressure of the pressurized air to a downstream one of any adjacent two of the at least two distributors (108,114).