Sleep questionnaires
Subjective sleep was assessed with two questionnaires (both self-report and proxy-report) from the Patient-Reported Outcomes Measurement Information System (PROMIS)23.
The PROMIS Pediatric Sleep Disturbance short form 8a consists of eight questions and assesses satisfaction with sleep, including difficulties and concerns with falling asleep and staying asleep. The PROMIS Pediatric Sleep Related Impairment short form 8a is another eight-item questionnaire, focusing on perceptions associated with sleep problems. It measures impaired alertness, tiredness and sleepiness during usual waking hours and impaired functioning. Parents complete similar proxy-versions. The questionnaires assess sleep over the past seven days, are generic rather than disease-specific and do not focus on symptoms of specific sleep disorders. Both questionnaires demonstrated strong internal consistency reliability and clinical validiy24. Raw scores are rescaled into T-scores with a mean of 50 and a standard deviation (SD) of 10. Questionnaire-specific cut-off points for moderate (75–94th percentile) and severe (≥ 95th percentile) sleep problems were used25.