Effects of VDT tasks with a bright display at night on melatonin, core temperature, heart rate, and sleepiness

Shigekazu Higuchi, Yutaka Motohashi, Yang Liu, Mio Ahara, Yoshihiro Kaneko

Abstract

The effects of performing video display terminal (VDT) tasks with a bright display (BD) at night on nocturnal salivary melatonin concentration, rectal temperature, heart rate, and sleepiness were examined. Seven healthy male adults performed exciting VDT tasks with a BD and a dark display (DD) and boring VDT tasks with a BD and a DD from 2300 to 0200. The light intensities of the BD and DD were 45 and 15 lx at each subject's eye level, respectively. The exciting VDT task with both BD and DD significantly suppressed the nocturnal decrease in rectal temperature and heart rate and the nocturnal increase in sleepiness. The BD significantly suppressed the nocturnal decrease in rectal temperature during both exciting and boring VDT tasks. The nocturnal salivary melatonin concentration was significantly suppressed by the combination of the exciting task and BD. The results suggest that performing an exciting VDT task with a BD suppresses the nocturnal changes in melatonin concentration and other physiological indicators of human biological clocks.

  • light
  • biological rhythm
  • video game
  • Internet
  • electroencephalogram
  • video display terminal

Footnotes

  • Address for reprint requests and other correspondence: S. Higuchi, Dept. of Public Health, Akita University School of Medicine, 1-1-1 Hondo, Akita City 010-8543, Japan (E-mail:higuchi{at}med.akita-u.ac.jp).

  • The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

  • First published January 17, 2003;10.1152/japplphysiol.00616.2002

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