The Effect of Zinc Supplementation on Sleep Quality of ICU Nurses: A Double Blinded Randomized Controlled Trial

Workplace Health Saf. 2018 Apr;66(4):191-200. doi: 10.1177/2165079917734880. Epub 2017 Dec 14.


This study examined the effect of zinc supplementation on the sleep quality (SQ) of intensive care unit (ICU) nurses. In a double-blind, randomized controlled trial, 54 ICU nurses were randomly assigned to the intervention group ( n = 27) that received 220 mg zinc sulfate capsules every 72 hours for 1 month and the control group ( n = 26) that received placebo. Sleep quality of ICU nurses was measured by calculating the total quality sleep score using the Pittsburgh Sleep Quality Index (PSQI). The serum zinc level was a secondary outcome. All measurements were calculated at both baseline and 1 month after intervention. The total PSQI, subjective SQ, and sleep latency scores for the intervention group were significantly lower than the control group, which means that the SQ of ICU nurses in the intervention group improved from baseline. The serum zinc level of the intervention group at the end of the study was significantly higher than the control group, which means that zinc supplementation improved participants' serum zinc level. Based on these findings, the researcher suggested that zinc supplementation could be associated with better SQ, subjective SQ, and sleep latency in this group of workers.

Keywords: PSQI; intensive care unit (ICU); nursing; nutrition; sleep quality; zinc supplement.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Astringents / pharmacology
  • Astringents / therapeutic use
  • Chi-Square Distribution
  • Dietary Supplements / standards
  • Double-Blind Method
  • Female
  • Humans
  • Intensive Care Units / organization & administration
  • Iran
  • Male
  • Nurses / psychology*
  • Placebos / pharmacology
  • Placebos / therapeutic use
  • Psychometrics / instrumentation
  • Psychometrics / methods
  • Sleep Wake Disorders / drug therapy*
  • Statistics, Nonparametric
  • Workforce
  • Zinc / analysis
  • Zinc / blood
  • Zinc Sulfate / pharmacology*
  • Zinc Sulfate / therapeutic use


  • Astringents
  • Placebos
  • Zinc Sulfate
  • Zinc