Effects of pre-bedtime blue-light exposure on ratio of deep sleep in healthy young men

Sleep Med. 2021 Aug:84:303-307. doi: 10.1016/j.sleep.2021.05.046. Epub 2021 Jun 8.


This study aimed to investigate the effects of pre-bedtime blue-light exposure on ratio of deep sleep and sleep quality. In this study, 11 healthy young men were exposed to three conditions for 1 h before bedtime: 1) incandescent light, 2) blue-light, or 3) blue light-blocking glasses on. The following morning, subjective sleep quality was measured using the Oguri-Shirakawa-Azumi Sleep Inventory. Sleep time, ratio of sleep, ratio of deep sleep, and body movements during sleep were measured using a mat sleep-scan (sleep scan, SL- 504; TANITA Corp., Japan) and an ambulatory portable sleep study system (LS-140; Fukuda Denshi Co. Ltd., Japan). Ratio of deep sleep was significantly decreased in the blue-light exposure group compared to the groups with incandescent light and blue light-blocking glasses (p < 0.01), There were no differences noted in sleep time or body movements among the three groups. These results suggest that blue-light exposure to affects sleep quality by reducing the ratio of deep sleep.

Keywords: Blue-light; Body temperature; Deep sleep; Sleep.

MeSH terms

  • Circadian Rhythm
  • Humans
  • Light
  • Male
  • Sleep
  • Sleep Disorders, Circadian Rhythm*
  • Sleep, Slow-Wave*