Table 4.

Hypothesis testing Sleep Disturbance‐23 and Sleep‐related Impairment‐11

We expected that:	Mean difference in T‐score (95% confidence interval) a
	Sleep Disturbance−23	Sleep‐related Impairment−11 b
1. The sleep‐clinic sample had higher scores than the high‐school students	10.6 (8.1–13.1)	8.6 (5.2–11.9)
2. The adolescents with sleep problems and/or relevant health issues had higher scores than healthy high‐school students	4.8 (3.5–6.2)	5.3 (3.5–7.1)
3. The high‐school students with relevant health issues had higher scores than healthy high‐school students	2.7 (1.2–4.2)	4.0 (2.0–6.0)
4. Adolescents who answered item Sleep20 ‘I had a sleep problem’ with a higher response category, would have higher scores
‘Not at all’ versus ‘A little bit’	6.1 (5.1–7.1)	4.5 (3.0–6.0)
‘A little bit’ versus ‘Somewhat’	2.2 (0.9–3.4)	3.9 (1.7–6.1)
‘Somewhat’ versus ‘Quite a bit/very much’	5.2 (4.0–6.5)	3.2 (0.6–5.7)

^aA mean difference of ≥2 points was considered clinically relevant.

^bCorrected for age and gender.