Participants were 86 shift-worker nurses aged 24 to 46 years.
Pouryaghoub Gholamreza, Aminian Omid, Sadeghniiat-Haghighi Khosro, Yazdi Zohreh 2008, 'Efficacy and hypnotic effects of melatonin in shift-work nurses: double-blind, placebo-controlledcrossover trial', Journal of Circadian Rhythmshttp://www.jcircadianrhythms.com/content/6/1/10. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)