Actigraphy
All participants wore an actigraph (Actiwatch Spectrum Plus, Respironics Inc.; Murrysville, PA) beginning after the completion of surgery, placed shortly after their arrival to the ICU. These devices were set to record activity counts in 15 s epochs. Actigraphy devices use accelerometry-based technology to determine activity counts per epoch based on wrist movement. For active patients (e.g., outside the ICU), contiguous periods of inactivity are thought to be rest and/or sleep, and periods of rest can usually be reliably scored by an experienced scorer. However, the activity levels of individuals recovering from surgery in the ICU are very low, and thus manual scoring of the actograms could potentially be unreliable. Thus, we standardized our analysis by defining 22:00 to 06:00 as the nighttime rest period for all individuals, and defined 06:00 to 22:00 as the daytime period. Based on our inpatient experience, the 10 p.m.–6 a.m. period is after nighttime medications are normally administered (9 p.m.), hall lights are dimmed, and is generally the time where rest/sleep is encouraged by bedside nurses. Choosing a “rest interval” was an effort to standardize the rest period and to compare between our randomly allocated groups regarding the amount of sleep captured by the device. We also excluded individuals who were intubated for the entire duration of the study (through POD 8). We did not examine actigraphy data beyond the day of ICU discharge as the participant had reached study completion. If a patient left the ICU before noon, this day was not included. All periods were categorized according to post-extubation day. For example, if a patient was extubated on POD 2, this was considered post-extubation day 0. Actiware software (Respironics Inc.) was utilized to extract data from the devices.