If you lie awake at night and have thought about trying a sleep app, you may wonder whether it can do what a face-to-face program does. A new Danish trial found that a nine-week, fully automated smartphone program based on cognitive behavioural therapy for insomnia (CBT-I) reduced insomnia severity more than waiting. Many people dropped out, and the trial cannot say how the app compares with other treatments or with other sleep apps.
The trial was published on 30 September 2026 in Internet Interventions, from researchers at Aarhus University and Aarhus University Hospital in Denmark. It tested one specific app, called Hvil, which delivers CBT-I automatically over nine weeks with no therapist involved. CBT-I is a structured, skills-based approach that is usually the first-line treatment for insomnia, but many people lack access to it.
Adults with insomnia, defined as a score of 10 or more on the Insomnia Severity Index, were randomly assigned to the app (83 people) or to a waitlist (82 people). The main outcome was insomnia severity, measured at the start, weekly during the programme and after it finished. Secondary outcomes included fatigue and sleep diary measures such as time in bed and night-time awakenings. The researchers analysed all randomised people using the intention-to-treat approach and looked at whether age, gender and how much people used the app changed the results.
Insomnia severity improved more in the app group than in the waitlist group, and the difference was statistically significant. The effect size was 0.66, which the authors describe as clinically meaningful and which most people would call moderate. There were also improvements in fatigue, sleep quality, time in bed and night-time awakenings. Effect sizes for these secondary outcomes ranged from small, at 0.15 for total sleep time, to large, at 1.06 for time in bed.
People who engaged more with the app tended to have larger drops in insomnia severity. That pattern is a link, not proof that more use caused better sleep, because people who are already improving may also use an app more.
The authors say attrition was substantial. The abstract does not give the exact share who dropped out, so it is best to read the full paper if you want the figure.
The comparison was with a waitlist, which means the trial shows that doing the program was better than doing nothing for nine weeks. It does not show that the app works better than other treatments, whether those are face-to-face CBT-I, other digital programs or other approaches. A waitlist also cannot separate the effect of the app's content from the effect of simply doing something about sleep and expecting to improve.
The authors describe the trial as preliminary, and it tested one product in one country. The result should not be read as meaning that sleep apps in general are effective. Apps differ a great deal in content, quality and how closely they follow evidence-based methods.
Because substantial numbers dropped out, the people who stayed may have been the ones more likely to keep going. That limits what we can say about how many people would engage in everyday life, and about how long benefits would last, since results were measured at the end of the programme.
Insomnia can also be linked with other health conditions, medicines, shift work, pain or mood problems. A trial of adults with insomnia cannot tell you whether a program would suit your circumstances. This article is general education and not personal advice, and it does not suggest that anyone should stop or change a medicine or treatment.
Digital programmes can widen access for people who live far from services or cannot afford regular appointments, but access is only useful if people can stay with the programme. The dropout in this trial is a reminder that convenience alone does not ensure that people keep going.
Source: Smartphone-delivered cognitive behavioral therapy for insomnia: A preliminary randomized controlled trial DOI: 10.1016/j.invent.2026.101007
AI-generated editorial illustration. The scene is fictional and does not depict a study participant or demonstrate treatment effectiveness. This article summarises published research in our own words and is general information, not personal health advice.
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