Postoperative delirium is a common complication that usually occurs acutely within the first 24 hours after surgery and resolves within 72 hours; it is common in all medical areas and particularly affects patients over the age of 65 and those with pre-existing cognitive impairments. It is characterized by difficulty organizing and coordinating thoughts and by slowing down motor functions that are observed for a short period after surgery.

The study will be an observational prospective study with historical control (pre/post-study) whose primary objective is to identify the incidence of postoperative delirium in patients undergoing cardiac surgery. The population will be adult patients undergoing cardiac surgery at our University Hospital over a period of 12 months. The intervention will be exposure to totally artificial light (for patients hospitalized after the relocation of the department to its original location). The comparator will be exposure to natural light (for patients who will be hospitalized during our temporary transfer to an environment with natural lighting). The outcome will be the incidence of delirium, measured with the Confusion Assessment Method-Intensive Care Unit (CAM-ICU) scale; episodes of agitation requiring sedative drugs; time elapsed before onset of delirium. The study will last 12 months.

Inclusion Criteria:

• planned cardiac surgery
• planned ICU admission after surgery

Exclusion Criteria:

• cardiac surgery with total suspension of cerebral perfusion
• patient with diagnosed dementia or major depressive disorder
• patient unable to perform CAM-ICU evaluation
• emergent surgery
• patient in ICU before surgery

All adult patients undergoing cardiac surgery with planned postoperative ICU admission. All tipes of cardiac surgery, irrespective of surgical access or technique, but excluding surgery performed under total circulatory arrest (totale suspension of brain perfusion). Patients will be excluded if they are unable to perform CAM-ICU assessment, if they were diagnosed with major depression or moderate/severe dementia and if they were already in ICU before surgery. Emergent surgery will also be an exclusion criteria.