Measures

All children underwent structured diagnostic interviews using the Anxiety Disorders Interview Schedule for DSM-IV - Child and Parent versions (ADIS-C/P).²⁹ The ADIS-C/P assesses a range of clinical symptoms, including anxiety, mood, and externalizing disorders and is considered the gold standard for diagnosing anxiety disorders in children, with high interrater and test-retest reliability.^30,31

Phone calls were completed daily on 7 consecutive evenings during which the parent and child indicated whether the child experienced any of the following symptoms that day: (1) muscle aches/tension, (2) headaches, and (3) stomach aches. All symptoms were rated on a scale from 0 (none) to 3 (a lot).

CHILD SLEEP HABITS QUESTIONNAIRE (CSHQ): Parents completed the CSHQ, a well-validated scale used to screen for a variety of sleep problems in children.³² The CSHQ includes the item, “Child grinds teeth during sleep” to which parents responded using 3-point scale: 1 (rarely), 2 (sometimes), 3 (usually). SB was considered to be present if parents reported that their child sometimes or usually grinds his or her teeth at night.

POLYSOMNOGRAPHY (PSG): Standard, multichannel PSG was conducted using Medcare amplifiers and Rembrandt version 9.0 Sleep Acquisition Software (Natus Medical Incorporated, Pleasanton, California, United States). Registered polysomnographic sleep technicians (RPSGT) experienced in working with children and scoring pediatric sleep records conducted and scored sleep studies in 30-second epochs based on American Academy of Sleep Medicine (AASM) criteria.³³ All studies were conducted and scored under the supervision of a board-certified sleep physician. All technicians were blinded to child diagnostic status. Electroencephalogram (EEG; frontal, central, and occipital regions), electrooculogram, EMG (submental, right/left tibial), electrocardiogram, nasal pressure, thoracic and abdominal respiratory effort, and oximetry data were collected.

PSG-DETECTED BRUXISM: Bruxism events were scored by trained study staff with previous PSG scoring experience and blind to child group status. Scoring was conducted in 30-second epochs in accordance with AASM criteria.³³ Bruxism events were scored during stage R sleep, stage N1 sleep, and stage N2 sleep. Powerline filters were set at 60 Hz, with additional high and low pass EMG filters set at 100 Hz and 10 Hz, respectively. Bruxism events were classified as either tonic (sustained EMG burst lasting more than 2 seconds), phasic (3 or more rhythmic EMG bursts of 0.25 to 2 seconds in duration), or mixed (both sustained and rhythmic). Children showing more than 2 bruxism episodes per hour of sleep received a diagnosis of SB.^34,35