Cognitive behavioural therapy for insomnia includes methods to adjust bedtimes and risetimes. The most well-known is sleep restriction therapy, but alternatives like sleep compression therapy and bedtime regularization also exist. Instructions and terminology vary. This scoping review uses “time-in-bed manipulation therapy” to encompass all such interventions, aiming to synthesize information on their implementation in adult populations, focusing on different instructions found in the literature. We searched five electronic databases. Two independent reviewers screened full-text papers, followed by data extraction. Both quantitative (e.g., instruction frequencies) and qualitative (e.g., analysis of content) syntheses were conducted. Of 7474 citations and 500 full-text papers, 52 studies met inclusion criteria, covering 60 therapies. Most interventions were termed sleep restriction therapy, but other names, such as sleep compression and bedtime restriction, were also used. Nine different methods for calculating the initial sleep window were identified, with further variation in other instructions. About half of the studies were randomized controlled trials. This review provides a comprehensive overview of time-in-bed manipulation therapies, aiding researchers and clinicians in selecting appropriate approaches. It highlights the need for clearer reporting, increased direct comparisons, and suggests a new model, The Restriction and Flexibility Model, describing key dimensions of these interventions.