Background Transcranial electrical stimulation (tES) has gained attention because of its potential to modulate human sleep physiology. However, its efficacy in healthy populations remains unclear.

Objectives This systematic review and meta-analysis aimed to evaluate the effects of tES on sleep in healthy adults.

Methods A comprehensive literature search was conducted across five electronic databases from January 5 to 10, 2023, to retrieve articles administering tES and evaluating its effects on sleep in healthy adults. The Cochrane Collaboration’s tool was used to assess the risk of bias. The meta-analysis was performed using random-effects models and robust variance estimation, with subgroup analyses and meta-regression to examine conditional and moderation effects.

Results Among the 1,182 identified articles, 39 were included in the qualitative synthesis, and 14 (N = 297) met the criteria for meta-analysis. The overall effect of tES on sleep was negligible (estimate: 0.00, 95% confidence interval [CI]: –0.18 to 0.19), with substantial heterogeneity. Subgroup meta-analysis revealed that pre-sleep tES prolonged sleep latency (estimate: –0.30, 95% CI: –0.49 to –0.11), whereas transcranial alternating current stimulation (tACS) increased total sleep time (estimate: 0.14, 95% CI: 0.01 to 0.27). Meta-regression analysis showed that tES efficacy was attenuated with increasing age (β: –0.01, 95% CI: –0.02 to 0.00).

Conclusions Although tES does not appear to have a substantial overall effect on sleep, tACS may improve total sleep time, and pre-sleep offline tES may prolong sleep latency. Further well-designed studies are warranted to confirm these findings and minimize potential biases.

The authors have declared no competing interest.

This work was funded by JST Moonshot R&D to MT (Grant Number JPMJMS2012).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

The fundamental statistics collected for each study (i.e., mean, standard deviation, sample size) and analysis codes are accessible on the OSF website (https://osf.io/jznce/).

https://osf.io/jznce/