[1] Larissa Univ Hosp, Larisa 41110, Greece
[2] Univ Thessaloniki, Sch Med, Pediat Pulmonol Unit, Larisa, Greece
[3] Univ Thessaloniki, Sch Med, Sleep Disorders Lab, Dept Pediat, Larisa, Greece
[4] Univ Thessaloniki, Sch Med, Sleep Disorders Lab, Dept Pulm, Larisa, Greece
[5] Univ Thessaloniki, Sch Med, Sleep Disorders Lab, Dept Physiol, Larisa, Greece
[6] Univ Pittsburgh, Sch Med, Div Pediat Pulm, Pittsburgh, PA USA
[7] Childrens Hosp, Pittsburgh, PA 15213 USA