An air conditioner system including a sleeping enclosure defining a sleeping space into which conditioned air is adapted to be delivered from one end or side of the sleeping space in a manner which maximizes contact between conditioned air and a person or persons in the sleeping space, the sleeping space including an upper air pervious section; and a lower relatively air impervious section adapted to surround a bed in the sleeping space and configured to minimize passage of the conditioned air from the sleeping space through the pervious section or other leakage paths; and an air conditioner unit for generating a conditioned air flow, wherein the impervious section extends to a height above the sleeping surface of the bed at the end or side of the bed opposed to said end or side sufficient to contain the conditioned air as it moves towards and returns from the opposite end or side of the sleeping space, and wherein the impervious section extends to a sufficiently increased height above the sleeping surface at the opposite end or side to allow the direction of air flow to reverse towards said one end or side without substantial loss of conditioned air through the pervious section.