60), suggesting significantly greater symptom severity compared to boys. Differences in PSQI scores did not reach significance (t47=−1.90, P=.07; d=0.57), suggesting negligible differences between girls and boys in sleep quality. Girls reported significantly greater WASO and TWT and significantly reduced TST and sleep efficiency compared to boys (t44=−2.72, P=.01, d=0.54; t45=−2.12, P=.04, d=0.24; t45=2.34, P=.02, d=0.68; t45=2.28, P=.03, d=0.30, respectively) but no difference in SOL or NWAK (P=.21 and P=.16, respectively).
Post hoc linear regressions found that when controlling for age, gender predicted WASO (t44=2.07, P=.04; f2=0.09), TWT (t45=2.39, P=.02; f2=0.13), and SE (t45=−2.18, P=.03; f2=0.11). In contrast, when controlling for age, gender did not predict baseline ISI (t47=1.42, P=.16; f2=0.04), PSQI (t47=1.31, P=.20’ f2=0.04), SOL (t45=−0.57, P=.23; f2=0.04), or NWAK (t45=0.88, P=.39; f2=0.02) or TST (t45=1.45, P=.15; f2=0.04). Notably, two variables identified as showing gender differences in the t tests, ISI and TST, were not significant predictors in the linear regressions, suggesting baseline gender differences in these variables are accounted for by boys being marginally younger in age.
Of relevance to the current study, there were no differences between boys and girls in the number of Sleep Ninja lessons completed (P=.42). Information regarding uptake and adherence to the intervention can be found in Werner-Seidler et al .
|Age (years), mean (SD)||13.70 (1.04)||14.47 (1.51)||.07|
|Reside in city, n (%)||13 (81)||30 (91)||.38|
|MHa treatment,b n (%)||0 (0)||13 (39)||.004|
|Medication use,c n (%)||1 (6)||13 (39)||.02|
|ISI,d mean (SD)||7.90 (4.63)||9.87 (5.00)||.04|
|Global PSQI,e mean (SD)||7.40 (3.78)||7.91 (3.90)||.07|
|SOL,f,g mean (SD)||0.82 (0.75)||0.73 (0.54)||.21|
|NWAK,f,h mean (SD)||1.50 (2.31)||0.65 (0.69)||.16|
|WASO,f,i mean (SD)||0.12 (0.18)||0.24 (0.26)||.01|
|TWT,f,j mean (SD)||1.13 (0.88)||1.40 (1.32)||.04|
|TST,f,k mean (SD)||8.74 (0.65)||8.14 (1.07)||.02|
|SEl (%), mean (SD)||88.70 (8.41)||85.80 (10.74)||.03|
aMH: mental health.
cPredominantly antidepressants, hormonal contraceptives, and melatonin.
dISI: Insomnia Severity Index.
ePSQI: Pittsburgh Sleep Quality Index.
fIn hours, derived by averaging the 7 baseline sleep diary entries.
gSOL: sleep onset latency.
hNWAK: number of awakenings.
iWASO: wake after sleep onset.
jTWT: total wake time.
kTST: total sleep time.
lSE: sleep efficiency.
Gender Differences in Treatment Response
Change in ISI and PSQI scores from pretreatment to posttreatment for each participant, grouped by gender, is represented in. Results from the mixed-model analysis are presented in . For insomnia symptom severity, time was a significant predictor of ISI in both models. The coefficient was negative, indicating that scores on the ISI decreased from pretreatment to posttreatment. Gender did not reach significance in either model. The gender by time interaction in model 2 was not significant. Age was not a moderator of any effect.
For sleep quality, time was a significant predictor of PSQI in model 1. The coefficient was negative, indicating that scores on the PSQI decreased from pretreatment to posttreatment. However, time did not remain a significant predictor of PSQI in model 2. Gender did not reach significance in either model. There was a trend in the gender by time interaction in model 2, but it was not significant. Age was not a moderator of any effect.
|Characteristic||Parameter estimate||SE||95% CI||P value|
|Intercept||1.94||6.21||−10.55 to 14.43||.76|
|Time||−4.83||0.63||−6.1 to −3.56||<.001|
|Gender||1.6||1.32||−1.06 to 4.26||.23|
|Age||0.8||0.46||−0.13 to 1.73||.09|
|Intercept||0.72||14.61||−28.66 to 30.12||.96|
|Time||−15.44||6.43||−28.5 to −2.38||.02|
|Gender||8.13||16.15||−24.39 to 40.66||.62|
|Age||0.87||1.1||−1.34 to 3.09||.43|
|Time×gender||−1.38||1.4||−4.13 to 1.37||.32|
|Time×age||0.84||0.47||−0.13 to 1.8||.09|
|Gender×age||−0.45||1.2||−2.87 to 1.97||.71|
|Intercept||1.25||5.82||−10.49 to 12.99||.83|
|Time||−2.13||0.45||−3.01 to −1.21||<.001|
|Gen