Table 1
Demographic information about the participants.
| Men (n = 3) | Women (n = 3) | |
|---|---|---|
| Age (yr) | 23.7 ± 3.2 | 20.7 ± 1.2 |
| Height (cm) | 172.7 ± 7.6 | 159.2 ± 5.3 |
| Weight (kg) | 66.2 ± 9.3 | 53.7 ± 2.6 |
| Beck Depression Inventory | 2.0 ± 1.7 | 1.0 ± 1.7 |
| Horne-Ostberg | 53.8 ± 9.3 | 59.3 ± 0.6 |
| Morningness-Eveningness Questionnaire | Intermediate | Intermediate |
| Usual Sleep Duration (min) | 450 ± 52.2 | 410.0 ± 45.8 |
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.
Figure 2
24-h rhythms of aMT6s Excretion at baseline and after treatment. Individual urinary 6-sulphatoxymelatonin data (aMT6s) were averaged into 90-min bins, normalized to percent of peak, and group means (+/– SEM, N = 6) plotted on a 12 noon to 12 noon axis to yield synchronized 24-h profiles representing rhythm timing and waveform at baseline (●) and post-treatment (ο). Color-filled rectangles represent the timing of light and exercise stimuli (light: yellow; exercise: blue). Color filled diamonds underneath the curves represent mean acrophase times before (green) and after (red) treatment. ANOVAs for the normalized 90-min time series (panels A,B,C) underscored robust 24-h rhythmicity [p’s < 0.001] and confirmed a significant phase shift (interaction) for the Light + Exercise treatment, but not for the other treatments.
Table 2
aMT6s baseline, timing of treatments, and phase shifts in the aMT6s acrophase for the individual participants.
| Base aMT6s Acrophase | Timing: After Phase (h:min) | aMT6s Acrophase Delay (min) | Base aMT6s Acrophase | Timing: After Phase (h:min) | aMT6s Acrophase Delay (min) | Base aMT6s Acrophase | Timing After Acrophase for Light & Exercise | aMT6s Acrophase Delay (min) | |
|---|---|---|---|---|---|---|---|---|---|
| 01 | 0137 h | –2:41 | –71 | 0244 h | –3:49 | –39 | 0205 h | –3:10 & +2:50 | –64 |
| 02 | 0419 h | –5:24 | –79 | 0410 h | –5:15 | –34 | 0440 h | –5:44 & +0:16 | –74 |
| 03 | 0147 h | –2:52 | –55 | 0115 h | –2.20 | –89 | 0244 h | –3:49 & +2:71 | –85 |
| 04 | 0443 h | –5:48 | –46 | 0438 h | –5:43 | –30 | 0426 h | –5:31 & +0:29 | –83 |
| 05 | 0619 h | –7:24 | –43 | 0538 h | –6:43 | –48 | 0503 h | –6:08 & -0:08 | –98 |
| 06 | 0345 h | –4:50 | –45 | 0302 h | –4:07 | –43 | 0313 h | –4:18 & 1:42 | –81 |
Table 3
Mean aMT6s data across the six participants.
| Treatment | Baseline aMT6s Acrophase (h) | Baseline CRQ Amplitude/Mesor | Stimulus Timing: H After Baseline Acrophase | Final aMT6s Acrophase (hr:min) | Final CRQ | aMT6s Phase Shift min |
|---|---|---|---|---|---|---|
| Bright Light | 0345 ± 1:48 | 1.22 ± 0.08 | –4.83 ± 1.81 | 0442 ± 1:43 | 1.29 ± 0.13 | –56.6 ± 15.2 |
| Exercise | 0335 ± 1:33 | 1.21 ± 0.16 | –4.66 ± 1.56 | 0422 ± 1:20 | 1.24 ± 0.12 | –47.3 ± 21.6 |
| Bright Light + Exercise | 0342 ± 1:11 | 1.24 ± 0.11 | Light: –4.78 ± 1.19 EX: 1.21 ± 1.19 | 0503 ± 1:19 | 1.31 ± 0.10 | –80.8 ± 11.6 |
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.