How Sleep Works: Sleep Drive & Body Clock
A plain-language CBT-I handout explaining sleep drive and the body clock (the two-process model of sleep), common insomnia traps, and space for clients to choose a first change.
1-page fillable PDF · US Letter (prints on A4) · Psychoeducation
- Approach / concern
- Sleep / CBT-I
- Technique
- Psychoeducation
- Format
- Fillable PDF, 1 page (US Letter / A4)
- Access
- Pro and Advanced plans (3-day free trial)
- For
- Licensed clinicians to use with clients
- Updated
- October 2026
Key facts
What is the How Sleep Works: Sleep Drive & Body Clock?
The two-process model of sleep regulation (Borbely, 1982) describes how a homeostatic sleep drive (Process S) and the circadian rhythm (Process C) together determine sleepiness and alertness. This model underpins the main behavioural components of CBT for insomnia, including sleep restriction and stimulus control.
Why it works
CBT-I is the recommended first-line treatment for chronic insomnia (Qaseem et al., 2016). Clients are much more likely to follow counter-intuitive instructions, like spending less time in bed, when they understand how sleep drive and the body clock work (Edinger & Carney, 2014).
When to use it
- Start of CBT-I
- Clients who go to bed early or sleep in to ‘catch up’
- Shift workers (adapted)
- Insomnia alongside depression, anxiety or pain
How to use it in session
- Explain the two systems using the balloon and clock metaphors.
- Ask the client which traps they recognize.
- Link the traps to their sleep diary data.
- Choose one change to try.
- Introduce sleep scheduling and stimulus control next.
Clinician tips
- Emphasize a fixed wake time as the anchor of the body clock.
- Expect skepticism about reducing time in bed and normalize it.
- Screen for sleep apnea and other medical causes where relevant.
Worked example
Sharing with clients
Members can download the PDF to print or email, or copy a private client link from the download box. Your client opens the link and downloads the worksheet on any device. No client account is needed, and nothing your client writes is stored on TherapyAid.
Frequently asked questions
What is the two-process model?
A scientific model describing how sleep pressure (which builds with time awake) and the circadian rhythm (a roughly 24-hour clock) interact to regulate sleep.
Is it okay to nap?
For people with insomnia, naps are usually best avoided or kept short and early, as they reduce night-time sleep drive.
References
Borbely, A. A. (1982). A two process model of sleep regulation. Human Neurobiology, 1(3), 195-204.
Edinger, J. D., & Carney, C. E. (2014). Overcoming insomnia: A cognitive-behavioral therapy approach, therapist guide (2nd ed.). Oxford University Press.
Qaseem, A., Kansagara, D., Forciea, M. A., Cooke, M., & Denberg, T. D. (2016). Management of chronic insomnia disorder in adults: A clinical practice guideline from the American College of Physicians. Annals of Internal Medicine, 165(2), 125-133.
This worksheet is an educational tool for use by, or under the guidance of, a licensed or registered mental-health professional. It is not a diagnostic instrument or a substitute for clinical judgement. If a client is in crisis in Canada, call or text 9-8-8 or call 9-1-1.
