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Guide

Keeping a sleep diary for CBT-I

By SGWNIFacts checked 7 November 2026

CBT-I is guided by your sleep diary. Your therapist uses it to set your time in bed and to see whether it's working, so keep it every morning for the whole course, including the good nights.

What CBT-I is

Cognitive behavioural therapy for insomnia combines education about sleep, changes to when and how you use your bed (stimulus control and sleep restriction), and work on the thoughts that keep you awake. The American Academy of Sleep Medicine strongly recommends it for long-term insomnia in adults. In the UK, the NHS says a GP may offer CBT, face to face or through an online programme.

Why it runs on a diary

The AASM's 2021 guideline describes treatment progressing on information from sleep diaries completed throughout the course, typically 4 to 8 sessions. Its earlier insomnia guideline says sleep restriction starts by limiting time in bed to your total sleep time from your baseline diary. Without the diary, your therapist is guessing.

What your therapist needs

  • Every night, every morning. Fill it in within an hour of getting up, as the Consensus Sleep Diary asks.
  • The times you were given. If your therapist set a bedtime and a getting-up time, record what you actually did. A late night isn't a failure; it's information.
  • Time to fall asleep and time awake. These drive your sleep efficiency, which is what most sleep restriction schedules are adjusted on.
  • Notes. Medication, a stressful day, illness, travel. In the focus groups behind the Consensus Sleep Diary, being able to add your own comments was the most consistent request.

Keeping it going

If the diary starts to slip, keep it where you'll see it on waking, and set a daily reminder. If you miss a night, leave it blank rather than reconstructing it later.

Don't start sleep restriction on your own from a guide like this one. It works, but the window is set and changed with your therapist, from your diary.

This guide isn't medical advice. If poor sleep has gone on for months or makes the day hard to cope with, see your doctor.

More guides

Sources

  1. Behavioral and psychological treatments for chronic insomnia disorder in adults. American Academy of Sleep Medicine, Journal of Clinical Sleep Medicine, 2021.CBT-I is the recommended treatment for chronic insomnia, and it is guided by sleep diaries kept through treatment. Checked 7 November 2026.
  2. Clinical Guideline for the Evaluation and Management of Chronic Insomnia in Adults. American Academy of Sleep Medicine, Journal of Clinical Sleep Medicine, 2008.A two-week sleep log before the first visit, what it records, and how total sleep time and sleep efficiency are worked out from it. Checked 7 November 2026.
  3. Insomnia. NHS.Symptoms, common causes, habits to change, and when to see a GP. Checked 7 November 2026.
  4. The Consensus Sleep Diary: Standardizing Prospective Sleep Self-Monitoring. Sleep, 2012.The sleep diary as the standard for describing your own sleep, the items it asks, and filling it in each morning. Checked 7 November 2026.
  5. Measuring Sleep Efficiency: What Should the Denominator Be?. Journal of Clinical Sleep Medicine, 2016.Sleep efficiency is usually total sleep time divided by time in bed; insomnia treatment commonly uses 85% as its threshold. Checked 7 November 2026.