Background: Sleep and circadian rhythms are markedly altered in intensive care unit (ICU) patients. Numerous factors related to the patient and the ICU environment affect the ability to initiate and maintain sleep. Therefore, nonpharmacological interventions could play an essential role in improving sleep and circadian rhythm. Objective: The aim of this study was to examine nonpharmacological interventions evaluated for promoting sleep in adult ICUs. Methods: A scoping review was conducted, including randomised controlled trials, nonrandomised controlled trials, quasi-experimental trials, and other controlled studies investigating the effects of nonpharmacological interventions promoting sleep in adult ICU patients. Results: A total of 57 articles and 14 ongoing trials were included in the review, of which 38 were randomised clinical trials. Nine nonpharmacological interventions to improve sleep in critically ill patients were evaluated: earplugs and/or eye masks, aromatherapy, bundles, music intervention, massage or acupressure, noise masking, bright light, and dynamic light. Most included trials simultaneously assessed the effect of more than one intervention on perceived sleep quality using questionnaires. The association between the interventions and improved sleep varied. In the case of multicomponent interventions, it is difficult to identify which components might have influenced sleep improvement. Conclusions: Numerous studies have evaluated various nonpharmacological interventions to promote sleep in critically ill patients, several of which improved perceived sleep quality. However, the substantial variability of the assessed interventions and their implementation complicates drawing reliable conclusions. (c) 2024 Australian College of Critical Care Nurses Ltd. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).