Variability of Impedance Pneumography Tidal Breathing Flow-volume Curves During Sleep in Healthy Children

Inclusion Criteria: * 18 months-6 years, both sexes * Healthy at the time of inclusion * Laboratory analyses in the reference range or not clinically relevant according to the investigator judgement * Lung function in the reference range with a negative bronchodilator test result * Signed informed consent Exclusion Criteria: * Preterm birth * Chronic respiratory disorder of prematurity * Recurrent bronchitis or recurrent hospitalizations because of a respiratory illness (recurrent pneumonia) * Primary immunodeficiency * Chronic rhinosinusitis, synonasal polyposis * Nasal congestion, adenotonsillar hypertrophy, signs and symptoms of sleep apnea or sleep disordered breathing * Acute respiratory infection or hospitalization because of an acute illness within 4 weeks prior to inclusion * Personal or family history or clinical evidence of asthma, atopy or other chronic respiratory disorders (high risk for asthma and allergy) * Use of asthma rescue or maintenance medication within 4 weeks prior to inclusion * Implanted or external active medical devices such as pacemakers