[1] Sir Charles Gairdner Hosp, Dept Pulm Physiol, Nedlands, WA, Australia
[2] Tan Tock Seng Hosp, Singapore, Singapore
[3] Univ Western Australia, West Australian Sleep Disorders Res Inst, Nedlands, WA 6009, Australia
[4] Univ Western Australia, Fac Sci, Nedlands, WA 6009, Australia