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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.


Experimental protocol: evening bright light followed by early morning exercise. Participants adhered to an ultra-short sleep-wake cycle beginning at 1600 h on Friday, and were subsequently exposed to 90 min of bright light (5000 lux, 2210–2340 h) followed 4.33 h later by 90 min of exercise (0410–0540 h). In the other two treatments, subjects received bright light alone or exercise alone at 2210–2340 h. Phase shifts of the aMT6s rhythm were calculated by subtracting final post treatment acrophase from baseline acrophase.
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Figure 1: Experimental protocol: evening bright light followed by early morning exercise. Participants adhered to an ultra-short sleep-wake cycle beginning at 1600 h on Friday, and were subsequently exposed to 90 min of bright light (5000 lux, 2210–2340 h) followed 4.33 h later by 90 min of exercise (0410–0540 h). In the other two treatments, subjects received bright light alone or exercise alone at 2210–2340 h. Phase shifts of the aMT6s rhythm were calculated by subtracting final post treatment acrophase from baseline acrophase.

Mentions: Laboratory Protocol: Ultra-Short Sleep-Wake Cycle. For each 2.5-day laboratory protocol, participants entered the laboratory at 1600 h on DAY 1 (Friday afternoon) and remained for 58–65 h until DAY 4 (Monday morning) (Figure 1). Upon arrival, participants were told which of the three treatments they would be performing: bright light alone, exercise alone, or bright light + exercise. Throughout each 2.5-day laboratory observation, participants followed a 3-h ultra-short sleep-wake schedule, in which participants were given 2-h intervals of out-of bed wakefulness in dim light (≤20 lux), followed by 1-h intervals for sleep in darkness (<1 lux). Chronobiologic protocols, such as the ultra-short sleep-wake cycle, are used to precisely assess circadian rhythms whose measurement can otherwise be masked by numerous environmental and behavioral factors, including, sleep, physical activity, caloric intake, posture, light exposure, and ambient temperature. By distributing these masking effects equally around the 24-h day, one can make inferences about the circadian system. Past research has shown that this schedule can be well-tolerated for up to 10 days [27, 30, 31].


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)

Experimental protocol: evening bright light followed by early morning exercise. Participants adhered to an ultra-short sleep-wake cycle beginning at 1600 h on Friday, and were subsequently exposed to 90 min of bright light (5000 lux, 2210–2340 h) followed 4.33 h later by 90 min of exercise (0410–0540 h). In the other two treatments, subjects received bright light alone or exercise alone at 2210–2340 h. Phase shifts of the aMT6s rhythm were calculated by subtracting final post treatment acrophase from baseline acrophase.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Experimental protocol: evening bright light followed by early morning exercise. Participants adhered to an ultra-short sleep-wake cycle beginning at 1600 h on Friday, and were subsequently exposed to 90 min of bright light (5000 lux, 2210–2340 h) followed 4.33 h later by 90 min of exercise (0410–0540 h). In the other two treatments, subjects received bright light alone or exercise alone at 2210–2340 h. Phase shifts of the aMT6s rhythm were calculated by subtracting final post treatment acrophase from baseline acrophase.
Mentions: Laboratory Protocol: Ultra-Short Sleep-Wake Cycle. For each 2.5-day laboratory protocol, participants entered the laboratory at 1600 h on DAY 1 (Friday afternoon) and remained for 58–65 h until DAY 4 (Monday morning) (Figure 1). Upon arrival, participants were told which of the three treatments they would be performing: bright light alone, exercise alone, or bright light + exercise. Throughout each 2.5-day laboratory observation, participants followed a 3-h ultra-short sleep-wake schedule, in which participants were given 2-h intervals of out-of bed wakefulness in dim light (≤20 lux), followed by 1-h intervals for sleep in darkness (<1 lux). Chronobiologic protocols, such as the ultra-short sleep-wake cycle, are used to precisely assess circadian rhythms whose measurement can otherwise be masked by numerous environmental and behavioral factors, including, sleep, physical activity, caloric intake, posture, light exposure, and ambient temperature. By distributing these masking effects equally around the 24-h day, one can make inferences about the circadian system. Past research has shown that this schedule can be well-tolerated for up to 10 days [27, 30, 31].

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.