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ReSomnia

Guide · 10-minute read

CBT-I, the therapy for insomnia, explained simply

Cognitive behavioural therapy for insomnia (CBT-I, sometimes written CBTi) is a drug-free method, lasting six to eight weeks, that works on the habits and thoughts that keep bad nights going. It is the recommended first-line treatment for chronic insomnia in adults, whether face to face or in digital form[1][2].

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By Andy Leleux, sleep technologist · Updated on 27 October 2026

Key points

  • Recommended first-line by European and American experts for chronic insomnia in adults[1][2].
  • Sleep restriction and stimulus control are among its most effective components[3][4].
  • A programme lasts six to eight weeks, with a sleep diary filled in every morning[7].
  • The first few weeks can be tiring: that is expected and temporary[7].

The guides

What is CBT-I?

CBT-I starts from a simple observation: when insomnia lasts, it is no longer just stress or the original event keeping it going, but the habits you picked up to compensate (staying in bed longer, napping, going to bed early “to catch up”) and thoughts that raise tension at bedtime. The therapy tackles both.

It requires no medication or device. Its basic tool is the sleep diary: each morning, you note when you went to bed, how long it took to fall asleep, any awakenings and when you got up. These notes are used to work out your sleep efficiency and to adjust the programme week by week.

The 2023 European guideline and the American Academy of Sleep Medicine's guideline both make it the first-line option for chronic insomnia in adults, whatever their age and even alongside other illnesses, whether face to face or in digital form[1][2].

Who is it for?

CBT-I is for adults whose sleep difficulties (falling asleep, staying asleep, waking too early) occur at least three nights a week for at least three months, with an effect on their day: tiredness, concentration, mood. Not sure if that's you? Read Do I have insomnia?.

When to talk to a doctor first

Epilepsy, bipolar disorder, severe daytime sleepiness or a job where alertness is critical (professional driving, machinery) call for medical advice before you reduce your time in bed[1][2]. Snoring with pauses in breathing or marked sleepiness can point to sleep apnoea, which is worth checking with your doctor: the Epworth test can help you start that conversation.

The five components of CBT-I

  1. Sleep restriction. Time in bed is limited to the time you actually sleep, so that sleep becomes deeper and more continuous again, then gradually extended. Step by step.
  2. Stimulus control. The bed is for sleeping: if you are awake for a long stretch, you get up and only go back when you feel sleepy again. Your brain relearns the link between bed and sleep. The instructions.
  3. Cognitive restructuring. You examine the thoughts that fuel worry (“if I don't sleep, tomorrow will be a disaster”) and replace them with more balanced ones. The method.
  4. Relaxation. Breathing and muscle relaxation: techniques to bring tension down before bed. The techniques and their limits.
  5. Sleep hygiene. Caffeine, alcohol, screens, light, regular hours: useful pointers, but not enough on their own to treat chronic insomnia[2][4]. The real advice.

Analyses comparing the components with each other rank sleep restriction among the most effective, along with stimulus control and, in one of them, work on thoughts; sleep hygiene and relaxation add little within it[3][4].

How a programme works

  1. One to two weeks of diary-keeping to find out your real schedule and how much you sleep.
  2. A sleep window: a fixed bedtime and a fixed wake-up time, worked out from your average sleep time. The wake-up time stays the same seven days a week.
  3. An adjustment every week based on your sleep efficiency: at 90% or more, the window widens by 15 minutes; between 85 and 89%, it stays the same; below 85%, it shrinks by 15 minutes, without going under 5 hours[7].
  4. Six to eight weeks in all, then you keep adjusting with the diary[7]. If difficult nights come back one day: what to do if you relapse.

What the studies show

Digital CBT-I programmes clearly reduce insomnia severity compared with no treatment, with a benefit still measurable a year later[5]. In a Norwegian trial of 1,721 adults, a fully automated online programme took the average insomnia score (ISI) from 19 to 10 in 9 weeks[6].

On average, CBT-I delivered by a therapist does slightly better than its digital version[5][10]. Support from a professional also helps people finish the programme[8][9]: the two options complement each other more than they compete.

The first few weeks

Cutting your time in bed is tiring at first. During the first two to three weeks, sleepiness increases and alertness drops, then both return to their starting level: at three months in a small study, they were no different from baseline[7].

Take care when driving

If you feel sleepy, don't drive and avoid anything dangerous. If the sleepiness is severe, talk to your doctor or clinician: your window can be widened.

CBT-I and sleeping pills

You don't have to stop your medication to start CBT-I. Any change to a sleeping pill or anti-anxiety medication is a decision to make with your doctor: never stop a medicine you take for sleep on your own. To find out more: Sleeping pills and CBT-I.

Noting each evening what you take (the medicine, the dose, the number of tablets) gives your doctor a precise picture of your use. It's one of the things the ReSomnia diary lets you track.

Face to face, online or with an app?

  • With a CBT-I-trained clinician (psychologist, doctor): the most studied option, tailored to your situation. In Belgium, the tcci.be directory (in French) lists trained clinicians.
  • With a digital programme: available straight away, anywhere, at your own pace. It applies the same method, with lighter support. What the studies show.
  • Both together: you follow the programme in the app and your clinician sees your diary and scores between sessions.

ReSomnia applies the recommended method, with a sleep diary, a sleep window adjusted each week and validated questionnaires. The app itself has not been through a clinical trial: it is a tool for following the method, alone or with your clinician, not a replacement for them.

Frequently asked questions

How long does CBT-I take?

Usually six to eight weeks, with a sleep diary filled in every morning. After that, you keep adjusting your hours with the diary for as long as it helps.

Can I do CBT-I on my own?

Yes, fully automated digital programmes have shown their value. On average, support from a therapist gives better results and helps people stick with the programme: if you can, combine the two.

How is it different from sleep hygiene?

Sleep hygiene (caffeine, screens, regular hours) is just one of the five components of CBT-I. On its own, it is not enough to treat chronic insomnia; sleep restriction and stimulus control are among the strongest components.

Do I have to stop my sleeping pills to start?

No. CBT-I doesn't require you to stop your medication. Any change to a medicine you take for sleep is a decision to make with your doctor, never on your own.

Is CBT-I reimbursed in Belgium?

Sessions with a psychologist can be partly reimbursed, depending on whether the clinician has signed the national agreement and on your health insurance fund. The reimbursement guide on tcci.be (in French) sets out the conditions. The ReSomnia app itself is free.

Is ReSomnia free?

Yes. The programme, the sleep diary, the questionnaires and sharing with your clinician are all free.

Read and do next

Sources

  1. [1] Riemann D, et al. The European Insomnia Guideline 2023. J Sleep Res. 2023;32(6):e14035. PubMed
  2. [2] Edinger JD, et al. Behavioral and psychological treatments for chronic insomnia disorder in adults: an AASM clinical practice guideline. J Clin Sleep Med. 2021;17(2):255-262. PubMed
  3. [3] Furukawa Y, et al. Components and delivery formats of cognitive behavioral therapy for chronic insomnia in adults. JAMA Psychiatry. 2024;81(4):357-365. PubMed
  4. [4] Steinmetz L, et al. Network meta-analysis examining efficacy of components of cognitive behavioural therapy for insomnia. Clin Psychol Rev. 2024;114:102507. PubMed
  5. [5] Soh HL, et al. Efficacy of digital cognitive behavioural therapy for insomnia: a meta-analysis. Sleep Med. 2020;75:315-325. PubMed
  6. [6] Vedaa Ø, et al. Effects of digital cognitive behavioural therapy for insomnia on insomnia severity: a large-scale randomised controlled trial. Lancet Digit Health. 2020;2(8):e397-e406. PubMed
  7. [7] Kyle SD, et al. Sleep restriction therapy for insomnia is associated with reduced objective total sleep time, increased daytime somnolence, and objectively impaired vigilance. Sleep. 2014;37(2):229-237. PubMed
  8. [8] Takano Y, et al. Remission, treatment response, and treatment adherence across the delivery methods of cognitive behavioral therapy for insomnia: a systematic review and meta-analysis of randomized controlled trials. Sleep Med Rev. 2025;84:102204. PubMed
  9. [9] Chan WS, et al. Assessing the short-term efficacy of digital cognitive behavioral therapy for insomnia with different types of coaching: randomized controlled comparative trial. JMIR Ment Health. 2024;11:e51716. PubMed
  10. [10] Kallestad H, et al. Mode of delivery of cognitive behavioral therapy for insomnia: a randomized controlled non-inferiority trial of digital and face-to-face therapy. Sleep. 2021;44(12):zsab185. PubMed

This guide provides information and does not replace advice from a doctor or psychologist. If you are in distress, call your local crisis line at any hour: 1813 or 0800 32 123 in Belgium, 116 123 in the UK and Ireland, 988 in the US. In immediate danger, call 112 in Europe or your local emergency number.

Start CBT-I for free.

ReSomnia guides you step by step: a sleep diary each morning, a sleep window adjusted each week, follow-up questionnaires, and your clinician by your side if you wish.

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The app itself is in French for now. English is on the way.