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Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise.

Youngstedt SD, Kline CE, Elliott JA, Zielinski MR, Devlin TM, Moore TA - J Circadian Rhythms (2016)

Bottom Line: In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols.Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol.Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Nursing and Health Innovation and College of Health Solutions, Arizona State University, Phoenix, AZ, US; Phoenix VA Health Care System, Phoenix, AZ, US.

ABSTRACT
Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect.

No MeSH data available.


Related in: MedlinePlus

Phase delays in aMT6s acrophase were greatest with light followed by exercise. The bar graph contrasts the group mean (-SEM, n = 6) phase delay shifts observed in aMT6s rhythm 24-h cosine acrophases determined pre- vs. post-stimulation in the three treatments [Bright Light (BL); Exercise (EX); and Bright Light + Exercise (L+E)]. ANOVA revealed that the phase delay following L + E was significantly greater than that following EX. Other comparisons were not significant.
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Figure 3: Phase delays in aMT6s acrophase were greatest with light followed by exercise. The bar graph contrasts the group mean (-SEM, n = 6) phase delay shifts observed in aMT6s rhythm 24-h cosine acrophases determined pre- vs. post-stimulation in the three treatments [Bright Light (BL); Exercise (EX); and Bright Light + Exercise (L+E)]. ANOVA revealed that the phase delay following L + E was significantly greater than that following EX. Other comparisons were not significant.

Mentions: Phase shift data for individual participants are displayed in Table 2. Mean aMT6s acrophase phase shift data are displayed in Figure 3 and Table 3. Mean aMT6s acrophase phase shift following Bright Light Alone, Exercise Alone, and Bright Light + Exercise was 56.6 ± 15.2 min, 47.3 ± 21.6 min, and 80.8 ± 11.6 min, respectively. Corresponding effect sizes for these shifts were 0.53, 0.54, and 1.04, respectively.


Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise.

Youngstedt SD, Kline CE, Elliott JA, Zielinski MR, Devlin TM, Moore TA - J Circadian Rhythms (2016)

Phase delays in aMT6s acrophase were greatest with light followed by exercise. The bar graph contrasts the group mean (-SEM, n = 6) phase delay shifts observed in aMT6s rhythm 24-h cosine acrophases determined pre- vs. post-stimulation in the three treatments [Bright Light (BL); Exercise (EX); and Bright Light + Exercise (L+E)]. ANOVA revealed that the phase delay following L + E was significantly greater than that following EX. Other comparisons were not significant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834751&req=5

Figure 3: Phase delays in aMT6s acrophase were greatest with light followed by exercise. The bar graph contrasts the group mean (-SEM, n = 6) phase delay shifts observed in aMT6s rhythm 24-h cosine acrophases determined pre- vs. post-stimulation in the three treatments [Bright Light (BL); Exercise (EX); and Bright Light + Exercise (L+E)]. ANOVA revealed that the phase delay following L + E was significantly greater than that following EX. Other comparisons were not significant.
Mentions: Phase shift data for individual participants are displayed in Table 2. Mean aMT6s acrophase phase shift data are displayed in Figure 3 and Table 3. Mean aMT6s acrophase phase shift following Bright Light Alone, Exercise Alone, and Bright Light + Exercise was 56.6 ± 15.2 min, 47.3 ± 21.6 min, and 80.8 ± 11.6 min, respectively. Corresponding effect sizes for these shifts were 0.53, 0.54, and 1.04, respectively.

Bottom Line: In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols.Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol.Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Nursing and Health Innovation and College of Health Solutions, Arizona State University, Phoenix, AZ, US; Phoenix VA Health Care System, Phoenix, AZ, US.

ABSTRACT
Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect.

No MeSH data available.


Related in: MedlinePlus