PROJECT SUMMARY
An evidence-based treatment that simultaneously addresses intensive care unit (ICU) sleep and circadian
disruption (SCD) is desperately needed. Such treatment is needed because patients admitted to the ICU are at
high risk for adverse outcomes resulting directly from acute SCD. It is well established among healthy controls
that acute SCD is associated with immediate negative consequences such as metabolic, cognitive,
cardiovascular, respiratory, skeletal muscle, and immune dysfunction. Normalization of sleep and circadian
processes improves these dysfunctions. In the ICU, sleep and circadian processes cannot be segregated, and
there are likely several overlapping domains of SCD (e.g., sleep duration, timing, architecture, and continuity,
and circadian alignment and amplitude). Thus, a bundled approach to sleep and circadian promotion holds the
most promise for reversing SCD, normalizing broader physiologic disruptions, and improving ICU outcomes.
To date, ICU sleep promotion bundles have had limited success in documenting improved sleep, and sleep
bundles have commonly ignored circadian disruption and circadian-based sleep promotion strategies. This is a
critical gap. Translation of circadian principles to ICU sleep promotion is essential because alignment between
biologic and clock time allows for subsequent strategic scheduling of behaviors, for example, scheduling sleep
promotion during the biologic night to improve sleep duration and quality. In addition, circadian alignment has
broader physiologic implications and related potential to improve function across a wide variety of organ
systems, for example, scheduling eating during the biologic day to improve glucose tolerance. Investigations to
date have not tested the effect of a multifaceted intervention that includes promotion of both circadian
alignment via photic and nonphotic zeitgebers and overnight sleep via non-pharmacologic strategies (sleep
chronobundle). The overall objective of this project is to test whether a sleep chronobundle, including daytime
bright light, time-restricted daytime feeding, increased daytime mobility, and overnight sleep promotion
mitigates ICU SCD. A mechanistic randomized controlled trial will be used to test our central hypotheses that a
sleep chronobundle will (1) align biologic and clock day-night; (2) overlap behaviors (e.g., sleeping and eating)
correctly with biologic time periods; and therefore (3) improve sleep and metabolic processes in the ICU. We
are focusing on sleep and glucose metabolism metrics because of their high relevance to critical illness.
Project aims include (1) Establishing the effect of the sleep chronobundle on circadian alignment via
sampling of urine 6-sulfatoxymelatonin; (2) Determining the impact of the sleep chronobundle on overnight
sleep using portable polysomnography; and (3) Defining the impact of the sleep chronobundle on glucose
tolerance via continuous glucose monitoring. Ultimately, this work will provide mechanistic insights into ICU
SCD and form the basis of studies that can test the impact of the sleep chronobundle on ICU outcomes.
