This article reports a Swedish research project designed to study the impact of a cyclic light system, sound absorbents, and selected interior design changes in rooms within an intensive care unit. The authors describe the limitations of many previously reported intensive care unit (ICU) design research projects, and believe that much more knowledge is needed, which reflects a multidisciplinary perspective. It is complicated to carry out intervention research in ICUs because of the condition of patients, family presence, staffing, and other issues. A combination of methodological approaches, close contact with the clinical field, secure funding, and clear communication within the multidisciplinary research team are of vital importance. The results from the authors' initial evaluation process are reported including patient interviews and data from medical records. The Medical Research Council's guideline for design and evaluation of complex interventions directed the actual project and forms the structure for this article.