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|
|Gender||1.02||1.24||−1.43 to 3.57||.39|
|Age||0.61||0.43||−2.66 to 1.48||.17|
|Intercept||8.87||13.63||−18.61 to 36.34||.52|
|Time||−2.06||4.58||−11.42 to 7.29||.66|
|Gender||−7.77||15.15||−38.32 to 22.78||.61|
|Age||0.004||1.03||−2.06 to 2.07||>.99|
|Time×gender||−1.82||0.96||−3.79 to 0.16||.07|
|Time×age||0.08||0.34||−0.6 to 0.77||.80|
|Gender×age||0.71||1.13||−1.57 to 2.98||.54|
aISI: Insomnia Severity Index.
bPSQI: Pittsburgh Sleep Quality Index.
This study compared self-reported insomnia symptom severity, sleep quality, sleep characteristics, and CBT-I treatment response between adolescent girls and boys with at least mild symptoms of insomnia. The results supported some of our predictions by showing that girls more often than boys reported sleep characteristics consistent with disturbed sleep, including increased nighttime wakefulness and reduced sleep efficiency. However, contrary to predictions, we found no differences in self-reported sleep quality on the PSQI or in difficulty falling asleep, and gender differences in symptom severity and total sleep duration were accounted for by boys being marginally younger in age. It is not immediately clear why girls reported sleep characteristics consistent with disturbed sleep but not poorer sleep quality on the PSQI or insomnia symptoms on the ISI (when controlling for age) compared to boys. One possible explanation is the nonclinical sample examined in the current study. Individuals with milder symptoms may experience greater symptom fluctuation consistent with individuals in the early stage of disorder development (prodromal phase; eg, ), which may be more effectively captured in state-based measures (eg, daily sleep diary) compared to trait-based measures reliant on self-report (eg, PSQI and ISI measure sleep parameters over the past 4 and 2 weeks, respectively).
Increased wakefulness after sleep onset in girls in the current study is consistent with previous reports showing women and adolescent girls more often report sleep characteristics consistent with increa