ENVIRONMENTAL tobacco smoke was associated with greater sleep fragmentation in children evaluated for suspected sleep-disordered breathing. Secondhand Smoke and Sleep FragmentationChildren exposed to environmental tobacco smoke had a 67% higher arousal index than unexposed children, according to a prospective study using overnight polysomnography and urinary cotinine testing. The higher arousal index among exposed children further indicated that environmental tobacco smoke may interrupt sleep continuity even when total sleep measures appear similar. Nevertheless, the findings support routinely assessing environmental tobacco smoke exposure when evaluating children with suspected sleep disorders. Environmental tobacco smoke and sleep fragmentation in children with suspected sleep apnea.