The purpose of this prospective observational study is to investigate if mechanically ventilated patients who are treated in one of the new intensive care unit (ICU) rooms have less delirium compared to patients who are treated in the conventional rooms on the same ICU. The investigators will further evaluate the impact on sleep quality, circadian rhythm, global cognitive function and general outcome parameters.

The investigators recorded light and noise conditions in the ICU rooms before start of the redesigning process (subproject light and noise in the intensive care unit (LiNo-ICU)). The investigators will compare data regarding light and noise in the ICU rooms before and after the redesigning process (non-patient related data; ethical vote amendment 08.05.2014).

Delirium is one of the most frequently seen brain organ dysfunctions in the intensive care unit (ICU). Depending on the ICU population, up to 87% have delirium at some point during their critical illness. Patients with delirium have a 3fold increased risk of dying compared to patients without delirium. Studies could show that sedation is the most common independent risk factor for transitioning to delirium. However, the no-sedation approach is often challenging. ICU patients who are not sedated often develop severe anxiety and agitation. These symptoms are often treated with sedatives that have delirogenic side effects.

One of the major reasons for anxiety and agitation of patients is the ICU environment which causes distress. The feelings of being surveyed all the time by monitors, being exposed to different kinds of machinery or equipment which sometimes do not work properly are major stressors.

The objective of the interdisciplinary research project "Parametrische (T)Raumgestaltung" was the development of two redesigned intensive care rooms that help to reduce patients' anxiety, helplessness and stress through a holistic architectural approach. The patient's perception and needs, his or her obvious feelings of helplessness and fear are the starting point for a concept that is able to reduce stress factors such as functional and purely technical environment, insufficient lighting conditions and noise. Minimizing or eliminating these common stress factors in the ICU could reduce the need for sedatives and thereby reducing the incidence of ICU delirium.

Inclusion Criteria:

• Male and female patients with age ≥ 18 years
• Expected intensive Care unit stay ≥ 48 hours
• Invasive mechanical ventilation or non-invasive mechanical ventilation (with positive ventilation pressure >6 hours/day and high flow >30 liters) on the day of intensive care unit admission

Exclusion Criteria:

• Participation in other clinical studies 10 days before study inclusion and during the study period
• Patients with psychiatric diseases
• Patients with a history of stroke and known residual cognitive deficits
• Patients with a history of cardiopulmonary arrest or pulseless electric activity with cardiopulmonary resuscitation followed by therapeutic hypothermia during entire hospital stay
• Analphabetism
• Anacusis or Hypoacusis with hearing aid device, Amaurosis
• Non-German speaking
• Allergies to any substance of the electrode fixing material
• Lacking willingness to save and hand out data within the study
• Accommodation in an institution due to an official or judicial order
• History of sleep disorders
• History or suspicion of hypoxic brain damage (e.g. intracranial bleeding)
• History or suspicion of elevated intracranial pressure in the last 7 days before study inclusion
• Patients with an open chest after cardiac surgery
• The informed consent of the patient or the subject's legally acceptable representative can´t be obtained in time
• Patient has a power of attorney or patient's provision, where he/she refuses participation in any clinical trial

Critically ill patients