Circadian rhythms in critically ill patients on the intensive care unit (ICU) are known to be severely disrupted. ICU patients also show reduced sleep efficiency, reduced rapid eye movement (REM) sleep, increased daytime sleep and significant sleep fragmentation. This effect seems to last post-discharge with studies suggesting that the prevalence of sleep disturbance in post-ICU patients is high.
The aetiology of sleep and circadian rhythm disruption (SCRD) on the ICU remains unclear and is likely to result from both internal and environmental disturbance. It seems likely to contribute to short term complications such as ICU delirium as well as longer term morbidity in those patients who survive to discharge. Delirium is a common complication of admission to the ICU. It is a state of acute confusion, experienced especially by older adults admitted to the ICU and is associated with longer ICU and hospital length of stay, significantly higher risk of functional decline, loss of independent living, and increased mortality. Unfortunately, recent treatment strategies using anti-psychotic medications and melatonin have failed to significantly reduce the incidence of delirium, and the role of SCRD remains unclear.
Through interrogation of large ICU datasets and detailed phenotyping, we aim to characterise and quantify disruption to circadian physiology in critically unwell patients – both on the intensive care unit and following discharge. Through this we hope to identify novel chronotherapeutic approaches to normalising these changes. These includes identifying novel pharmacological interventions, time of dose dependence of routinely used medications, optimising feeding strategies and targeting environmental adaptations to the ICU (e.g. noise/light).