Efficacy and Acceptability of Licensed and Off-Label Pharmacological Interventions for Insomnia in Patients With Severe Mental Illness: A Systematic Review and Meta-Analysis of Randomised Trials.

Background: A wide range of drugs is used to alleviate insomnia symptoms in individuals with severe mental illness (SMI), including licensed drugs and sedating drugs prescribed off-label. Yet, no review has gathered the evidence on illness-specific or transdiagnostic outcomes of pharmacological interventions for insomnia. We aimed to perform a systematic review and meta-analysis of randomised controlled trials (RCTs) studying the efficacy and acceptability of pharmacological interventions for insomnia among individuals with SMI, defined as schizophrenia, bipolar disorder (BD) or major depressive disorder (MDD).

Methods: We searched for RCTs of pharmacological interventions for insomnia that used either placebo or another medication as inactive control or active comparator. Two independent reviewers performed the literature screening, data extraction and risk of bias assessment (RoB2). We performed random effects meta-analyses on the co-primary outcomes total sleep time (TST), sleep quality and acceptability (all-cause discontinuation) and the secondary outcomes safety and tolerability.

Results: The search identified 3331 hits, of which 25 RCTs (n = 2476 individuals) were included, with 18 RCTs (n = 2199) in MDD, 4 RCTs (n = 162) in BD and 3 RCTs (n = 115) in schizophrenia. Of 25 RCTs, 22 had a high risk of bias. The most frequently studied drugs were agomelatine (RCTs = 3, n = 686), eszopiclone (RCTs = 3, n = 599) and zolpidem (RCTs = 3, n = 601). Compared to placebo, pharmacological interventions for insomnia were associated with improved sleep quality by a small effect size (RCTs = 8, g = 0.24, 95% CI = 0.05-0.43) and improved TST (RCTs = 10, MD = 30.82 min, 95% CI = 19.13-42.50), with similar acceptability (RCTs = 10, RR = 1.06, 95% CI = 0.90-1.25).

Discussion: Despite their frequent use, many licensed and off-label pharmacological interventions for insomnia have never been investigated in patients with SMI. The studies that provided sufficient data for meta-analysis showed better efficacy with similar acceptability compared to placebo, but the generalizability of these results is limited by the high heterogeneity and low quality of the included studies. This underscores the need for high-quality RCTs to provide a better scientific basis for the pharmacological treatment of insomnia in SMI.

Trial registration: CRD42023413787.