Does online insomnia treatment reduce depressive symptoms? A randomized controlled trial in individuals with both insomnia and depressive symptoms

<jats:title>Abstract</jats:title><jats:sec id="S0033291718001149_sec_a1"><jats:title>Background</jats:title><jats:p>Insomnia is effectively treated with online Cognitive Behavioral Therapy for Insomnia (CBT-I). Previous research has suggested the effects might not be limited to sleep and insomnia severity, but also apply to depressive symptoms. Results, however, are mixed.</jats:p></jats:sec><jats:sec id="S0033291718001149_sec_a2" sec-type="methods"><jats:title>Methods</jats:title><jats:p>In this randomized controlled trial we investigated the effects of guided online CBT-I on depression and insomnia in people suffering from symptoms of both. Participants (<jats:italic>n</jats:italic> = 104) with clinical insomnia and at least subclinical depression levels were randomized to (1) guided online CBT-I and sleep diary monitoring (i-Sleep) or (2) control group (sleep diary monitoring only). The primary outcome was the severity of depressive symptoms (Patient Health Questionnaire-9 without sleep item; PHQ-WS). Secondary outcomes were insomnia severity, sleep diary parameters, fatigue, daytime consequences of insomnia, anxiety, and perseverative thinking.</jats:p></jats:sec><jats:sec id="S0033291718001149_sec_a3" sec-type="results"><jats:title>Results</jats:title><jats:p>At post-test, participants in the i-Sleep condition reported significantly less depressive symptoms (PHQ-WS) compared with participants in the sleep-diary condition (<jats:italic>d</jats:italic> = 0.76). Large significant effects were also observed for insomnia severity (<jats:italic>d</jats:italic> = 2.36), most sleep diary parameters, daytime consequences of insomnia, anxiety, and perseverative thinking. Effects were maintained at 3 and 6 month follow-up. We did not find significant post-test effects on fatigue or total sleep time.</jats:p></jats:sec><jats:sec id="S0033291718001149_sec_a4" sec-type="conclusion"><jats:title>Conclusions</jats:title><jats:p>Findings indicate that guided online CBT-I is not only effective for insomnia complaints but also for depressive symptoms. The effects are large and comparable with those of depression therapy. Clinical trial registration number: NTR6049 (Netherlands Trial Register).</jats:p></jats:sec>