Sleep during and following critical illness: A narrative review

Abstract

Sleep is a complex process influenced by biological and environmental factors. Disturbances of sleep quantity and quality occur frequently in the critically ill and remain prevalent in survivors for at least 12 mo. Sleep disturbances are associated with adverse outcomes across multiple organ systems but are most strongly linked to delirium and cognitive impairment. This review will outline the predisposing and precipitating factors for sleep disturbance, categorised into patient, environmental and treatment-related factors. The objective and subjective methodologies used to quantify sleep during critical illness will be reviewed. While polysomnography remains the gold-standard, its use in the critical care setting still presents many barriers. Other methodologies are needed to better understand the pathophysiology, epidemiology and treatment of sleep disturbance in this population. Subjective outcome measures, including the Richards-Campbell Sleep Questionnaire, are still required for trials involving a greater number of patients and provide valuable insight into patients’ experiences of disturbed sleep. Finally, sleep optimisation strategies are reviewed, including intervention bundles, ambient noise and light reduction, quiet time, and the use of ear plugs and eye masks. While drugs to improve sleep are frequently prescribed to patients in the ICU, evidence supporting their effectiveness is lacking.

Keywords: Critical illness; Critical care; Sleep; Sleep deprivation; Polysomnography; Melatonin

Core Tip: Disturbed sleep is common among the critically ill and contributes to adverse physiological and psychological outcomes. Multiple contributory factors have been identified, including environmental, care-related and patient elements. Assessing sleep in the ICU is challenging, and objective and subjective methods are required to evaluate the disruption to sleep architecture and the patient’s experience of this. Both pharmacological and non-pharmacological interventions to improve sleep quality and quantity have been studied with mixed results, however, a multimodal approach to sleep optimisation is likely necessary to improve outcomes.