Laboratory sleep studies using polysomnography conducted on a single night may be suitable for ruling in sleep disordered breathing in children, but with a negative test, a second night may be needed to definitively rule out the problem in children, Belgian researchers report.

The findings run counter to current guidelines suggesting that single-night polysomnography (PSG) is sufficient for working up sleep disordered breathing in children.

An additional night of testing may be necessary because single-night PSG carries a false negative rate of 9 percent. This may relate to a phenomenon called the “first night effect”, which involves reductions in sleep quality probably due to several factors, such as the unfamiliarity of the sleep laboratory setting and the discomfort of the electrodes placed on the skin during the test.

In the present study, Dr. S. L. Verhulst, from the University of Antwerp, and colleagues tested for a “first night effect” and assessed whether single-night PSG was adequate to diagnose obstructive sleep apnea syndrome (OSAS) in 70 children and adolescents.

The researchers found evidence of a first night effect, primarily involving a reduction in REM sleep on the first night compared to the second night.

The ability of first night PSG to correctly identify OSAS ranged from 86 percent in children between 2 and 6 years of age to 100 percent in adolescents.

Overall, as noted, first night PSG had a false positive rate of 9 percent. Save for one child, all of the missed cases involved mild OSAS.

In addition, seven patients with evidence of OSAS on night one had a normal PSG on night two. Clearly, more research is needed, the authors conclude.

SOURCE: Archives of Diseases of Childhood, March 2006.