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Melatonin and Sleep in Preventing Hospitalized Delirium: A Randomized Clinical Trial

Actigraphy analysis methods and terms. Vertical lines represent the activity count in a 15-second epoch. Red markers at base of actigraphy bars represent epochs scored as awake by the software/algorithm. Light channel (yellow) removed from panels B and C in order to demonstrate activity patterns. (A) Hospitalized adult with long sleep bouts. Rest intervals (light blue background) are determined by the scorer, using decreased activity levels and light level changes, as periods where the subject is likely to be sleeping/trying to sleep. Sleep bouts within the rest interval are determined by the software’s algorithm, which scores sleep or wake based on activity count thresholds in a particular epoch and multiple surrounding epochs; the sum total of these sleep bouts give the total duration of sleep within a particular interval. Please note the clear changes in activity level between daytime and nighttime, as well as the minimal amount of wrist activity during sleep for this individual. (B) Hospitalized adult with short sleep bouts. Here, sleep within the rest interval is characterized by multiple short sleep bouts (examples shown with arrows in this panel), suggesting substantial sleep fragmentation. (C) Acutely ill, hospitalized adult with Confusion Assessment Method–positive delirium. This individual was noted to become delirious overnight. Note the increased and prolonged activity during the night, as well as the lack of sleep. Daytime rest periods ≥30 minutes were designated as naptime rest intervals; naps were summed together with the nighttime sleep to determine the total sleep time for a 24-hour period. Gray area in this panel is time prior to the start of the device’s recording.

Studies suggest that melatonin may prevent delirium, a condition of acute brain dysfunction occurring in 20%-30% of hospitalized older adults that is associated with increased morbidity and mortality. We examined the effect of melatonin on delirium prevention in hospitalized older adults while measuring sleep parameters as a possible underlying mechanism.


This was a randomized clinical trial measuring the impact of 3 mg of melatonin nightly on incident delirium and both objective and subjective sleep in inpatients age ≥65 years, admitted to internal medicine wards (non-intensive care units). Delirium incidence was measured by bedside nurses using the confusion assessment method. Objective sleep measurements (nighttime sleep duration, total sleep time per 24 hours, and sleep fragmentation as determined by average sleep bout length) were obtained via actigraphy. Subjective sleep quality was measured using the Richards Campbell Sleep Questionnaire.


Delirium occurred in 22.2% (8/36) of subjects who received melatonin vs in 9.1% (3/33) who received placebo (P = .19). Melatonin did not significantly change objective or subjective sleep measurements. Nighttime sleep duration and total sleep time did not differ between subjects who became delirious vs those who did not, but delirious subjects had more sleep fragmentation (sleep bout length 7.0 ± 3.0 vs 9.5 ± 5.3 min; P = .03).


Melatonin given as a nightly dose of 3 mg did not prevent delirium in non-intensive care unit hospitalized patients or improve subjective or objective sleep.

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-Stuti J. Jaiswal, MD, PhD, Thomas J. McCarthy, MD, Nathan E. Wineinger, PhD, Dae Y. Kang, PhD, Janet Song, Solana Garcia, Christoffel J. van Niekerk, MD, Cathy Y. Lu, Melissa Loeks, MPH, Robert L. Owens, MD

This article originally appeared in the September issue of The American Journal of Medicine.

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