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) designresearch projects, and believe that much more knowledge is needed, which reflects a multidisciplinaryperspective. It is complicated to carry out intervention research in ICUs because of thecondition of patients, family presence, staffing, and other issues. A combination of methodologicalapproaches, close contact with the clinical field, secure funding, and clear communication withinthe multidisciplinary research team are of vital importance. The results from the authors’ initialevaluation process are reported including patient interviews and data from medical records. TheMedical Research Council’s guideline for design and evaluation of complex interventions directedthe actual project and forms the structure for this article. Key words: environment, experimentalstudy, intensive care, nursing intervention, research