Early evening light mitigates sleep compromising physiological and alerting responses to subsequent late evening light

Marije te Kulve*, Luc J. M. Schlangen, Wouter D. van Marken Lichtenbelt

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

18 Citations (Web of Science)

Abstract

The widespread use of electric light and electronic devices has resulted in an excessive exposure to light during the late-evening and at night. This late light exposure acutely suppresses melatonin and sleepiness and delays the circadian clock. Here we investigate whether the acute effects of late-evening light exposure on our physiology and sleepiness are reduced when this light exposure is preceded by early evening bright light. Twelve healthy young females were included in a randomised crossover study. All participants underwent three evening (18:30-00:30) sessions during which melatonin, subjective sleepiness, body temperature and skin blood flow were measured under different light conditions: (A) dim light, (B) dim light with a late-evening (22:30-23:30) light exposure of 750 lx, 4000 K, and (C) the same late-evening light exposure, but now preceded by early-evening bright light exposure (18.30-21.00; 1200 lx, 4000 K). Late-evening light exposure reduced melatonin levels and subjective sleepiness and resulted in larger skin temperature gradients as compared to dim. Interestingly, these effects were reduced when the late-evening light was preceded by an early evening 2.5-hour bright light exposure. Thus daytime and early-evening exposure to bright light can mitigate some of the sleep-disruptive consequences of light exposure in the later evening.

Original languageEnglish
Article number16064
Number of pages12
JournalScientific Reports
Volume9
DOIs
Publication statusPublished - 5 Nov 2019

Keywords

  • HUMAN CIRCADIAN SYSTEM
  • BRIGHT LIGHT
  • BODY-TEMPERATURE
  • BLOOD-FLOW
  • MELATONIN SUPPRESSION
  • CORE TEMPERATURE
  • HIGH-SENSITIVITY
  • MORNING LIGHT
  • HEART-RATE
  • ALERTNESS

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