Circadian Biology and Its Importance to Intensive Care Unit Care and Outcomes

Abstract

Circadian rhythms are an integral part of life on earth. Circadian rhythms play a fundamental role in homeostasis as they ensure coordination between the environment and an organism's behavior and physiology. This coordination is called entrainment. Entrainment depends on environmental cues known as zeitgebers. Human zeitgebers include light (primary zeitgeber), sleep, eating, exercise, and activity. Circadian rhythms are disrupted in critically-ill patients due to both critical illness and current intensive care unit (ICU) practices. Disruptions in circadian rhythms are tightly linked with ICU sleep disruption. Together these entities potentiate numerous adverse outcomes including delirium, metabolic derangements, cardiovascular instability, and immune compromise. Herein, we will highlight potential areas for care improvement via chronobundles. We suggest bright light during the day, maintaining darkness, and protecting sleep at night, intermittent rather than continuous feeds, and activity via mobilization during the day. Optimizing circadian rhythms is a low-risk intervention that is underutilized in current ICU practice. This optimization could be a powerful tool in helping to improve outcomes in the critically-ill patient.

Sleep and circadian health 6 months after critical COVID‐19 disease

“…Also, pharmacological treatments within this context and the use of IMV are related to several sleep and circadian‐related sequelae. 10 …”

“…Also, pharmacological treatments within this context and the use of IMV are related to several sleep and circadian-related sequelae. 10 This study has some limitations. First, given the context of COVID-19, it was not possible to perform a baseline evaluation of sleep and circadian function, preventing the identification of possible sleep and circadian alterations prior to hospitalization or SARS-CoV-2 infection.…”

Light Levels in ICU Patient Rooms: Dimming of Daytime Light in Occupied Rooms

“…Poor sleep in the ICU includes all domains of sleep deficiency: poor sleep quality, insufficient sleep duration, and irregular circadian rhythms. Promotion of circadian alignment is a critically important strategy for improving sleep in all of these domains (2).…”

“…Poor sleep in the hospital, particularly in the intensive care unit (ICU), is a key determinant of patient satisfaction and healing (1, 2). Poor sleep in the ICU includes all domains of sleep deficiency: poor sleep quality, insufficient sleep duration, and irregular circadian rhythms.…”

Pilot Observational Study to Detect Diurnal Variation and Misalignment in Heart Rate Among Critically Ill Patients

“…Circadian misalignment in the intensive care unit (ICU) is likely caused by multifactorial insults of acute critical illness with or without associated brain dysfunction, abnormal light exposure, continuous nutritional intake, immobility, and pleiotropic medication effects (13,14). Circadian rhythm disruption overlaps and potentiates ICU sleep disruption forming a vicious cycle for critically ill patients.…”