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Table 4 Descriptive statistics for sleep latency, nighttime sleep duration, and CBCL T scores as a function of positive/negative screen for the Pediatric Sleep Questionnaire SRBD scale and Sleepiness subscale

From: Sleep characteristics and problems of 2-year-olds with Williams syndrome: relations with language and behavior

Measure N M (SD) Mdn (IQR) Range Mann-Whitney U (positive vs. negative)
Z p Cohen’s d
Sleep latency (min)
 SRBD
  Positive 15 40.00 (20.96) 30 (30–60) 15–90 1.11 .266 0.23
  Negative 81 34.49 (21.69) 30 (18.5–45.0) 5–90
 Sleepiness
  Positive 21 34.38 (17.51) 30 (17.5–48.5) 10–60 0.70 .486 0.08
  Negative 49 32.82 (21.86) 30 (16–45) 10–90
Nighttime sleep duration (hr)
 SRBD
  Positive 15 10.05 (1.29) 10.5 (9–11) 7.5–12.3 0.83 .405 0.17
  Negative 81 10.42 (1.05) 10.5 (9.8–11) 7.3–13.3
 Sleepiness
  Positive 21 10.50 (1.22) 10.5 (9.6–11.4) 8.3–13.3 0.07 .944 0.01
  Negative 49 10.51 (0.94) 10.5 (10–11) 8.3–12.5
CBCL DSM-5-based scales
 Depressive Problems T
  SRBD
   Positive 15 67.73 (6.02) 67 (63–72) 56–77 5.13 < .001* 1.21
   Negative 81 56.21 (5.22) 56 (51–60) 50–70
  Sleepiness
   Positive 21 61.29 (8.44) 60 (54–67) 50–77 2.45 .014 0.86
   Negative 49 55.90 (5.13) 56 (51–60) 50–67
 Anxiety Problems T
  SRBD
   Positive 15 52.60 (3.96) 51 (50–54) 50–60 2.13 .033* 0.37
   Negative 81 51.15 (2.35) 50 (50–51) 50–60
  Sleepiness
   Positive 21 50.90 (2.28) 50 (50–51) 50–60 0.20 .843 0.05
   Negative 49 51.02 (2.29) 50 (50–51) 50–60
 Autism Spectrum Problems T
  SRBD
   Positive 15 59.47 (7.38) 58 (54–61) 51–79 2.63 .016* 0.50
   Negative 81 55.74 (7.14) 54 (51–58) 50–87
  Sleepiness
   Positive 21 58.05 (8.66) 58 (51–61) 50–87 0.76 .448 0.27
   Negative 49 56.12 (6.44) 54 (51–61) 50–70
 Attention/Hyperactivity Problems T
  SRBD
   Positive 15 62.87 (6.42) 64 (57–67) 54–76 4.27 < .001* 0.95
   Negative 81 54.64 (5.97) 52 (50–51) 50–76
  Sleepiness
   Positive 21 60.71 (7.04) 60 (55.5–65.5) 51–76 4.50 < .001* 1.21
   Negative 49 53.41 (5.53) 51 (50–54) 50–76
 Oppositional Defiant Problems T
  SRBD
   Positive 15 56.80 (9.07) 52 (50–64) 50–77 2.77 .006* 0.53
   Negative 81 51.30 (2.81) 50 (50–51) 50–64
  Sleepiness
   Positive 21 54.33 (6.77) 51 (50–57) 50–70 2.02 .043 0.79
   Negative 49 51.12 (2.12) 50 (50–52) 50–59
CBCL 2007 Scale
 Stress Problems T
  SRBD
   Positive 15 61.27 (10.41) 63 (53–67) 51–85 3.87 < .001* 0.83
   Negative 81 53.00 (4.12) 51 (50–53) 50–70
  Sleepiness
   Positive 21 56.81 (8.61) 53 (51–60.5) 50–85 2.87 .004* 0.66
   Negative 49 52.92 (4.37) 51 (50–53) 50–70
CBCL Higher-order Factor Scales
 Internalizing Problems T
  SRBD
   Positive 15 56.80 (6.39) 59 (51–60) 45–68 3.14 .002* 0.67
   Negative 81 49.48 (7.94) 47 (45–55.5) 29–66
  Sleepiness
   Positive 21 51.43 (8.77) 51 (47–58.5) 33–68 1.04 .300 0.21
   Negative 49 49.67 (8.04) 47 (45–56) 29–64
 Externalizing Problems T
  SRBD
   Positive 15 61.20 (9.40) 58 (54–65) 47–80 4.51 < .001* 1.03
   Negative 81 47.48 (8.31) 46 (40–54) 31–67
  Sleepiness
   Positive 21 57.00 (9.92) 56 (50–61) 39–80 4.09 < .001* 1.22
   Negative 49 46.49 (7.97) 46 (40–51.5) 32–64
 Total Problems T
  SRBD
   Positive 15 62.67 (5.82) 62 (57–66) 55–73 5.19 < .001* 1.25
   Negative 81 49.33 (7.40) 50 (43–55) 31–65  
  Sleepiness
   Positive 21 56.81 (8.07) 57 (53–61) 40–73 3.81 < .001* 1.13
   Negative 49 48.33 (7.30) 50 (43–53.5) 31–65
  1. CBCL Child Behavior Checklist, SRBD Sleep-Related Breathing Disorder, IQR interquartile range, min minutes, hr hours, DSM-5 Diagnostic and Statistical Manual of Mental Disorders-5
  2. *Difference remains statistically significant after Holm-Bonferroni correction