Can melatonin improve shift workers' tolerance of the night shift? Some preliminary findings

Chronobiol Int. 1993 Oct;10(5):315-20. doi: 10.3109/07420529309064485.


The pineal hormone melatonin is potentially useful in the treatment of disorders, especially sleep disorders, associated with circadian rhythm disturbance. We have examined its effects on sleep, mood, and behaviour in a double-blind, placebo-controlled study of a small group of police officers working spans of seven successive night shifts. Compared to placebo, and to no treatment, melatonin (5 mg) taken at the desired bedtime improved problems related to sleep and increased alertness during working hours, especially during the early morning. In letter-target performance tests visual search speed and accuracy were either unchanged or slightly improved. Memory scanning speed and perception of mental load were adversely affected. This preliminary study suggests that melatonin has beneficial effects on sleep and alertness, but that its effects on performance need careful evaluation.

Publication types

  • Clinical Trial
  • Comparative Study

MeSH terms

  • Adult
  • Circadian Rhythm / drug effects*
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Melatonin / therapeutic use*
  • Memory / drug effects
  • Memory / physiology
  • Mental Processes / drug effects
  • Mental Processes / physiology
  • Middle Aged
  • Sleep / drug effects*
  • Sleep Wake Disorders / drug therapy*
  • Sleep Wake Disorders / prevention & control
  • Wakefulness / drug effects
  • Work Schedule Tolerance*


  • Melatonin