Actiwatches” are small actigraphy-based wristband data loggers that record a digitally integrated measure of gross motor activity. For this study, the Respironics Actiwatch-2 was used to provide objective data on sleep schedule variability, sleep quantity and quality statistics, and daytime activity patterns. In addition to sleep/wake activity recording, the Actiwatch-2 measured the amount and duration of ambient white light illuminance. Participants’ level of activity was scored at 1-minute increments (epochs), and participants were instructed to wear the device continuously on their nondominant wrist from enrollment until discharge from the hospital. If any participant’s stay lasted more than 28 days, a new Actiwatch-2 was given to the participant to replace the original for continuous data collection. After device removal and data download, raw data were analyzed using computerized sleep scoring software (Respironics Actiware v.5.70.1; Phillips Respironics, Bend, Oregon), which scores each epoch on the basis of a threshold method algorithm. The medium threshold setting (40 counts/min) was used for this analysis. Prior studies have shown high sensitivity with moderate accuracy for detecting sleep in populations with normal and disturbed sleep when compared with polysomnography. Investigators reviewed each sleep period prior to analysis to screen for malfunctioning watches, corrupt data, and required adjustments using bedtimes and wake times from the diary self-reports when necessary.