How Effective Is Digital CBT-I for Improving Sleep and Mood?

 Lin, W., Li, N., Yang, L., & Zhang, Y. (2023). The efficacy of digital cognitive behavioral therapy for insomnia and depression: A systematic review and meta-analysis of randomized controlled trials. PeerJ, 11, Article e16137. https://doi.org/10.7717/peerj.16137

Summary by: Cecilia Gutierrez Zepeda

Insomnia and depression often occur together, creating a cycle that can be difficult to break. People who struggle to fall asleep or stay asleep are more likely to experience low mood, and those experiencing depression often report ongoing sleep problems. Cognitive Behavioral Therapy for Insomnia (CBT-I) is one of the most effective treatments available for insomnia, but accessing it can be a challenge. There are not enough trained clinicians, and therapy can be expensive or inconvenient for many people.

To address this gap, researchers have developed digital CBT-I, which delivers similar therapeutic strategies through online platforms or apps. But how well does digital CBT-I work, especially for people who also experience symptoms of depression? That is the question Lin and colleagues (2023) set out to answer in their systematic review and meta-analysis.

The study focused on the effectiveness of digital CBT-I in improving two major outcomes: insomnia severity and depressive symptoms.

The authors examined studies that directly compared digital CBT-I to a control condition, such as a waitlist group, a placebo intervention, or treatment as usual without specific sleep treatment. They also wanted to see not only whether symptoms improved right after completing digital CBT-I, but also whether improvements lasted over time.

The researchers searched several major scientific databases, including PubMed, Embase, the Cochrane Library, and Web of Science. They looked for randomized controlled trials (RCTs), which are among the strongest research designs for testing whether a treatment works.

To be included in the analysis, each study had to meet several criteria:

• The participants had to be adults with insomnia and depressive symptoms.

• The intervention needed to be a digital or online form of CBT-I.

• The study needed to measure both insomnia and depressive symptoms.

• The design had to randomly assign participants to digital CBT-I or a control group.

After screening the results, the researchers included seven RCTs involving several thousand participants. They used a statistical method called random-effects meta-analysis, which allows researchers to combine results from different studies while accounting for differences among them. The researchers then calculated standardized mean differences (SMDs) to show how much the treatment improved insomnia and depression compared to the control groups.

The main findings were that, overall, digital CBT-I showed meaningful improvements in both insomnia and depressive symptoms. Participants who received digital CBT-I reported significantly lower insomnia severity at the end of treatment compared to participants in control groups. This effect was large in size (SMD = −0.85). When researchers examined follow-up periods ranging from six weeks to six months, these improvements remained substantial (SMD = −0.71). This suggests that the benefits were not limited to the immediate treatment period.

In addition, the researchers found that digital CBT-I led to moderate improvements in depressive symptoms on the Patient Health Questionnaire (PHQ). The benefits appeared immediately after treatment (SMD = −0.47) and were also present at follow-up (SMD = −0.42), although the effect sizes were smaller than those for insomnia. However, results based on another depression measure (HADS) did not reach statistical significance. This suggests that targeting sleep through CBT-I may also have positive effects on mood, even when depression is not the primary focus of treatment.

One notable strength of this meta-analysis is that it combined results from multiple studies, providing a broader picture of the effectiveness of digital CBT-I. The study also included only randomized controlled trials, which strengthens the reliability of the findings. Another strength is that the authors examined both immediate and follow-up outcomes, offering a more complete picture of how digital CBT-I works over time. Examining both sleep and depressive symptoms also highlights how treatments for one condition can influence another connected area of mental health.

Despite the promising findings, the authors noted several limitations. Only seven studies met the inclusion criteria, which means more research is needed to confirm and expand the findings. There was also variation in the interventions. Some digital CBT-I programs were fully automated, while others included some level of human support. The length and structure of the programs differed too, making it harder to determine which features were most effective. Moreover, the studies showed considerable variation in their effect sizes, a sign of heterogeneity, particularly for insomnia outcomes. Follow-up periods were also relatively short, and not all studies included follow-up assessments. This makes it difficult to determine how long the improvements last beyond the periods studied.

Future studies could examine several important questions. Longer follow-up periods would help researchers understand how durable the benefits of digital CBT-I truly are. Studies that examine program engagement and adherence could also clarify how usage patterns influence treatment success. Furthermore, future research might focus on combining digital CBT-I with other therapeutic approaches or personalizing digital interventions based on specific user characteristics.

This study provides encouraging evidence that digital CBT-I is a promising option for people struggling with sleep problems and that it may provide additional benefits for mood. Digital tools have the potential to reach more people than traditional therapy formats, especially those who lack access to in-person services.

By demonstrating that digital CBT-I can reduce insomnia severity and may also improve depressive symptoms, this research supports the growing role of digital mental health interventions in healthcare systems around the world.