Circadian phase-delaying effects of bright light alone and combined with exercise in humans

Shawn Youngstedt, Daniel F. Kripke, Jeffrey A. Elliott

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

In a within-subjects (n = 18), counterbalanced design, the circadian phase-shifting effects of 3 h of 1) bright light (3,000 lx) alone 2) and bright light combined with vigorous exercise were compared. For each treatment, volunteers spent 3 nights and 2 days in the laboratory, typically receiving the treatment from ∼2300 to 0200 on night 2. Bedtimes and waketimes were fixed to the volunteers' habits. Illumination was 50 lx during other wake hours and 0 lx during sleep. Bright Light Alone elicited a significant phase delay in rectal temperature minimum (70 min), but not in urinary 6-sulphatoxymelatonin (6-SMT) acrophase (20 min). Bright Light + Exercise elicited a significant phase delay in 6-SMT (68 min), but did not result in a significant difference in shift compared with Bright Light Alone. The study had adequate statistical power (80%) to detect phase-shift differences between treatments of ∼2-2.5 h. Thus any antagonism of light shifts with exercise could not have been revealed. Within the limited exercise and light parameters of this study, the results suggest that exercise does not reliably modulate phase-shifting effects of late night bright light in humans.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume282
Issue number1 51-1
StatePublished - 2002
Externally publishedYes

Fingerprint

Exercise
Light
Volunteers
Lighting
Habits
Sleep
Therapeutics
Temperature
6-sulfatoxymelatonin

Keywords

  • 6-sulphatoxymelatonin
  • Acrophase
  • Body temperature
  • Phase shift

ASJC Scopus subject areas

  • Physiology

Cite this

Circadian phase-delaying effects of bright light alone and combined with exercise in humans. / Youngstedt, Shawn; Kripke, Daniel F.; Elliott, Jeffrey A.

In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 282, No. 1 51-1, 2002.

Research output: Contribution to journalArticle

@article{ad131bf57ce146969e4e64f935b4407d,
title = "Circadian phase-delaying effects of bright light alone and combined with exercise in humans",
abstract = "In a within-subjects (n = 18), counterbalanced design, the circadian phase-shifting effects of 3 h of 1) bright light (3,000 lx) alone 2) and bright light combined with vigorous exercise were compared. For each treatment, volunteers spent 3 nights and 2 days in the laboratory, typically receiving the treatment from ∼2300 to 0200 on night 2. Bedtimes and waketimes were fixed to the volunteers' habits. Illumination was 50 lx during other wake hours and 0 lx during sleep. Bright Light Alone elicited a significant phase delay in rectal temperature minimum (70 min), but not in urinary 6-sulphatoxymelatonin (6-SMT) acrophase (20 min). Bright Light + Exercise elicited a significant phase delay in 6-SMT (68 min), but did not result in a significant difference in shift compared with Bright Light Alone. The study had adequate statistical power (80{\%}) to detect phase-shift differences between treatments of ∼2-2.5 h. Thus any antagonism of light shifts with exercise could not have been revealed. Within the limited exercise and light parameters of this study, the results suggest that exercise does not reliably modulate phase-shifting effects of late night bright light in humans.",
keywords = "6-sulphatoxymelatonin, Acrophase, Body temperature, Phase shift",
author = "Shawn Youngstedt and Kripke, {Daniel F.} and Elliott, {Jeffrey A.}",
year = "2002",
language = "English (US)",
volume = "282",
journal = "American Journal of Physiology - Endocrinology and Metabolism",
issn = "0193-1849",
publisher = "American Physiological Society",
number = "1 51-1",

}

TY - JOUR

T1 - Circadian phase-delaying effects of bright light alone and combined with exercise in humans

AU - Youngstedt, Shawn

AU - Kripke, Daniel F.

AU - Elliott, Jeffrey A.

PY - 2002

Y1 - 2002

N2 - In a within-subjects (n = 18), counterbalanced design, the circadian phase-shifting effects of 3 h of 1) bright light (3,000 lx) alone 2) and bright light combined with vigorous exercise were compared. For each treatment, volunteers spent 3 nights and 2 days in the laboratory, typically receiving the treatment from ∼2300 to 0200 on night 2. Bedtimes and waketimes were fixed to the volunteers' habits. Illumination was 50 lx during other wake hours and 0 lx during sleep. Bright Light Alone elicited a significant phase delay in rectal temperature minimum (70 min), but not in urinary 6-sulphatoxymelatonin (6-SMT) acrophase (20 min). Bright Light + Exercise elicited a significant phase delay in 6-SMT (68 min), but did not result in a significant difference in shift compared with Bright Light Alone. The study had adequate statistical power (80%) to detect phase-shift differences between treatments of ∼2-2.5 h. Thus any antagonism of light shifts with exercise could not have been revealed. Within the limited exercise and light parameters of this study, the results suggest that exercise does not reliably modulate phase-shifting effects of late night bright light in humans.

AB - In a within-subjects (n = 18), counterbalanced design, the circadian phase-shifting effects of 3 h of 1) bright light (3,000 lx) alone 2) and bright light combined with vigorous exercise were compared. For each treatment, volunteers spent 3 nights and 2 days in the laboratory, typically receiving the treatment from ∼2300 to 0200 on night 2. Bedtimes and waketimes were fixed to the volunteers' habits. Illumination was 50 lx during other wake hours and 0 lx during sleep. Bright Light Alone elicited a significant phase delay in rectal temperature minimum (70 min), but not in urinary 6-sulphatoxymelatonin (6-SMT) acrophase (20 min). Bright Light + Exercise elicited a significant phase delay in 6-SMT (68 min), but did not result in a significant difference in shift compared with Bright Light Alone. The study had adequate statistical power (80%) to detect phase-shift differences between treatments of ∼2-2.5 h. Thus any antagonism of light shifts with exercise could not have been revealed. Within the limited exercise and light parameters of this study, the results suggest that exercise does not reliably modulate phase-shifting effects of late night bright light in humans.

KW - 6-sulphatoxymelatonin

KW - Acrophase

KW - Body temperature

KW - Phase shift

UR - http://www.scopus.com/inward/record.url?scp=0036087267&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0036087267&partnerID=8YFLogxK

M3 - Article

VL - 282

JO - American Journal of Physiology - Endocrinology and Metabolism

JF - American Journal of Physiology - Endocrinology and Metabolism

SN - 0193-1849

IS - 1 51-1

ER -