Longer Single-Session Interventions May Not Be Better: Evidence From Two Randomized Controlled Trials With Online Workers Facing Mental-Health Struggles
Restricted accessBrief reportFirst published online March, 2026
Longer Single-Session Interventions May Not Be Better: Evidence From Two Randomized Controlled Trials With Online Workers Facing Mental-Health Struggles
Online, self-guided single-session interventions (SSIs), which provide a complete mental-health intervention in one brief experience, promise to increase global access to evidence-based support. One way to expand current SSIs’ reach is to shorten them, but doing so could also compromise their effectiveness. We conducted two randomized trials to test if shortening evidence-based SSIs reduces their efficacy among adult online workers facing mental-health struggles. In Study 1 (N = 262), the 8-min Overcoming Loneliness SSI reduced loneliness over 8 weeks more than a 23-min version of it (b = 2.64; d = 0.22, 95% confidence interval = [0.02, 0.41]; p = .03). In Study 2 (N = 1,145), 15-min, 9-min, 5-min, and 3-min versions of the Action Brings Change SSI did not significantly differ in how much they affected depression 8 weeks later (ps > .14). Our results suggest that longer digital SSIs are not necessarily more helpful than shorter ones.
BatesD.MächlerM.BolkerB.WalkerS. (2015). Fitting linear mixed-effects models using lme4. Journal of Statistical Software, 67, 1–48. https://doi.org/10.18637/jss.v067.i01
2.
BottaroR.ValentiG. D.FaraciP. (2023). Assessment of an epidemic urgency: Psychometric evidence for the UCLA loneliness scale. Psychology Research and Behavior Management, 16, 2843–2855. https://doi.org/10.2147/PRBM.S406523
ChapkovskiP.PeerE.BrandtE. (2024). From WEIRD to GREAT? Exploring data quality of global platforms for online research. OSF. https://doi.org/10.31234/osf.io/xvfqn
5.
CohenK.SchleiderJ. (2022). Adolescent dropout from brief digital mental health interventions within and beyond randomized trials. Internet Interventions, 27, Article 100496. https://doi.org/10.1016/j.invent.2022.100496
6.
CuijpersP.MiguelC.HarrerM.PlessenC. Y.CiharovaM.PapolaD.EbertD.KaryotakiE. (2023). Psychological treatment of depression: A systematic overview of a ‘Meta-Analytic Research Domain.’Journal of Affective Disorders, 335, 141–151. https://doi.org/10.1016/j.jad.2023.05.011
FaulF.ErdfelderE.LangA.-G.BuchnerA. (2007). G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behavior Research Methods, 39(2), 175–191. https://doi.org/10.3758/BF03193146
9.
FeingoldA. (2009). Effect sizes for growth-modeling analysis for controlled clinical trials in the same metric as for classical analysis. Psychological Methods, 14(1), 43–53. https://doi.org/10.1037/a0014699
10.
FunderD. C.OzerD. J. (2019). Evaluating effect size in psychological research: Sense and nonsense. Advances in Methods and Practices in Psychological Science, 2(2), 156–168. https://doi.org/10.1177/2515245919847202
11.
GreenP.MacLeodC. J. (2016). SIMR: An R package for power analysis of generalized linear mixed models by simulation. Methods in Ecology and Evolution, 7(4), 493–498. https://doi.org/10.1111/2041-210X.12504
12.
HartmanR.MossA. J.JaffeS. N.RosenzweigC.LItmanL.RobinsonJ. (2023). Introducing connect by CloudResearch: Advancing online participant recruitment in the digital age. OSF. https://doi.org/10.31234/osf.io/ksgyr
13.
HickinN.KällA.ShafranR.SutcliffeS.ManzottiG.LanganD. (2021). The effectiveness of psychological interventions for loneliness: A systematic review and meta-analysis. Clinical Psychology Review, 88, Article 102066. https://doi.org/10.1016/j.cpr.2021.102066
14.
HughesM. E.WaiteL. J.HawkleyL. C.CacioppoJ. T. (2004). A short scale for measuring loneliness in large surveys: Results from two population-based studies. Research on Aging, 26(6), 655–672. https://doi.org/10.1177/0164027504268574
JakobsenJ. C.GluudC.WetterslevJ.WinkelP. (2017). When and how should multiple imputation be used for handling missing data in randomised clinical trials – A practical guide with flowcharts. BMC Medical Research Methodology, 17(1), Article 162. https://doi.org/10.1186/s12874-017-0442-1
17.
KällA.JägholmS.HesserH.AnderssonF.MathaldiA.NorkvistB. T.ShafranR.AnderssonG. (2020). Internet-based cognitive behavior therapy for loneliness: A pilot randomized controlled trial. Behavior Therapy, 51(1), 54–68. https://doi.org/10.1016/j.beth.2019.05.001
18.
KaveladzeB. T.GastelumS. F.NgoD.-A. C.DelacruzP.CohenK. A.KällA.AnderssonG.SchleiderJ.SchuellerS. M. (2025). A randomized controlled trial comparing brief online self-guided interventions for loneliness. Journal of Consulting and Clinical Psychology, 93(1), 54–63. https://doi.org/10.1037/ccp0000908
19.
KazdinA. E.BlaseS. L. (2011). Rebooting psychotherapy research and practice to reduce the burden of mental illness. Perspectives on Psychological Science, 6(1), 21–37. https://doi.org/10.1177/1745691610393527
20.
KenwardM. G.RogerJ. H. (1997). Small sample inference for fixed effects from restricted maximum likelihood. Biometrics, 53(3), 983–997.
21.
KroenkeK.StrineT. W.SpitzerR. L.WilliamsJ. B. W.BerryJ. T.MokdadA. H. (2009). The PHQ-8 as a measure of current depression in the general population. Journal of Affective Disorders, 114(1), 163–173. https://doi.org/10.1016/j.jad.2008.06.026
22.
KuznetsovaA.BrockhoffP. B.ChristensenR. H. B. (2017). lmerTest Package: Tests in linear mixed effects models. Journal of Statistical Software, 82, 1–26. https://doi.org/10.18637/jss.v082.i13
23.
Lorenzo-LuacesL.DierckmanC.LindC.PeipertA.de Jesús-RomeroR.BussJ. F.RamirezI.StarvaggiI.AdamsS.HowardJ.FiteR. E. (2024). A pragmatic randomized controlled trial of stepped care cognitive-behavioral therapy for internalizing distress in adults. Cognitive Therapy and Research, 48(5), 998–1013. https://doi.org/10.1007/s10608-024-10489-7
24.
Lorenzo-LuacesL.HowardJ. (2023). Efficacy of an unguided, digital single-session intervention for internalizing symptoms in web-based workers: Randomized controlled trial. Journal of Medical Internet Research, 25, Article e45411. https://doi.org/10.2196/45411
25.
McCashinD.MurphyC. M. (2023). Using TikTok for public and youth mental health–A systematic review and content analysis. Clinical child Psychology and Psychiatry, 28(1), 279–306.
26.
OdgersK.KershawK. A.LiS. H.GrahamB. M. (2022). The relative efficacy and efficiency of single- and multi-session exposure therapies for specific phobia: A meta-analysis. Behaviour Research and Therapy, 159, Article 104203. https://doi.org/10.1016/j.brat.2022.104203
27.
OphirY.SissoI.AsterhanC. S. C.TikochinskiR.ReichartR. (2020). The turker blues: Hidden factors behind increased depression rates among Amazon’s mechanical turkers. Clinical Psychological Science, 8(1), 65–83. https://doi.org/10.1177/2167702619865973
28.
OsbornT. L.RodriguezM.WasilA. R.Venturo-ConerlyK. E.GanJ.AlemuR. G.RoeE.ArangoG, S.OtienoB. H.WasangaC. M.ShingletonR.WeiszJ. R. (2020). Single-session digital intervention for adolescent depression, anxiety, and well-being: Outcomes of a randomized controlled trial with Kenyan adolescents. Journal of Consulting and Clinical Psychology, 88(7), 657–668. https://doi.org/10.1037/ccp0000505
29.
R Core Team. (2015). R: A language and environment for statistical computing [Computer software]. R Foundation for Statistical Computing.
30.
RussellD. W. (1996). UCLA Loneliness Scale (Version 3): Reliability, validity, and factor structure. Journal of Personality Assessment, 66(1), 20–40. https://doi.org/10.1207/s15327752jpa6601_2
31.
RyanR. M.DeciE. L. (2000). Self-determination theory and the facilitation of intrinsic motivation, social development, and well-being. The American Psychologist, 55(1), 68–78. https://doi.org/10.1037//0003-066x.55.1.68
32.
SchleiderJ. L.BurnetteJ. L.WidmanL.HoytC.PrinsteinM. J. (2020). Randomized trial of a single-session growth mind-set intervention for rural adolescents’ internalizing and externalizing problems. Journal of Clinical Child & Adolescent Psychology, 49(5), 660–672.
33.
SchleiderJ.DobiasM. L.SungJ. Y.MullarkeyM. C. (2020). Future directions in single-session youth mental health interventions. Journal of Clinical Child & Adolescent Psychology, 49(2), 264–278. https://doi.org/10.1080/15374416.2019.1683852
34.
SchleiderJ.MullarkeyM. C.FoxK. R.DobiasM. L.ShroffA.HartE. A.RoulstonC. A. (2022). A randomized trial of online single-session interventions for adolescent depression during COVID-19. Nature Human Behaviour, 6(2), Article 2. https://doi.org/10.1038/s41562-021-01235-0
SchleiderJ.ZapataJ. P.RapoportA.WescottA.GhoshA.KaveladzeB.SzkodyE.AhuviaI. L. (2025). Single-session interventions for mental health problems and service engagement: Umbrella review of systematic reviews and meta-analyses. Annual Review of Clinical Psychology, 21, 279–303. https://doi.org/10.1146/annurev-clinpsy-081423-025033
37.
ThibaultR. T.ZavalisE. A.MaličkiM.PedderH. (2024). An evaluation of reproducibility and errors in published sample size calculations performed using G*Power. medRxiv. https://doi.org/10.1101/2024.07.15.24310458
38.
WickhamH.AverickM.BryanJ.ChangW.McGowanL. D.FrançoisR.GrolemundG.HayesA.HenryL.HesterJ.KuhnM.PedersenT. L.MillerE.BacheS. M.MüllerK.OomsJ.RobinsonD.SeidelD. P.SpinuV.. . . YutaniH. (2019). Welcome to the Tidyverse. Journal of Open Source Software, 4(43), Article 1686. https://doi.org/10.21105/joss.01686
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
