First night effect for polysomnographic data in children and adolescents with suspected sleep disordered breathing

Aims: To assess the presence of a first night effect (FNE) in children and adolescents and to examine if a single night polysomnography (PSG) is sufficient for diagnosing obstructive sleep apnoea syndrome (OSAS). Methods: Prospective case study of 70 patients (group 1: 2-6 years, n = 22; group 2: 7-12 years, n = 32; group 3: 13-17 years, n = 16) referred for OSAS. Diagnostic criteria for OSAS: one or more of the following: ( 1) obstructive apnoea index (OAI) >= 1; ( 2) obstructive apnoea hypopnoea index (oAHI) >= 2; (3) SaO(2) <= 89% in association with obstruction. Results: In all age groups, but mainly in the oldest children, REMS increased during the second night, mainly at the expense of stage 2 sleep. The first night PSG correctly identified OSAS in 86%, 91%, and 100% of the children for groups 1, 2, and 3 respectively. This represents 9% false negatives for OSAS when only the first night PSG was used. All cases missed had mild OSAS, except for one with oAHI > 5 on night 2. There were also seven patients with OSAS on night 1 but with a normal PSG on night 2: all had oAHI < 5. Conclusion: There is a FNE in children and adolescents. A single night PSG is sufficient for diagnosing OSAS, but in cases with a suggestive history and examination and with a negative first night, a second night study might be advisable.