Table 2. Follow-up values for the caffeine intake and sleep status variables according to the three intervention groups.
| Variables | Intervention groups* | |||||
|---|---|---|---|---|---|---|
| Group A | Group B | Group C | ||||
| Placebo | γ-PGA | Placebo | VitB6 | Placebo | γ-PGA + VitB6 | |
| Caffeine intake (mg/day) | 315.9 ± 340.4 | 237.5 ± 212.8 | 143.2 ± 147.1 | 82.1 ± 105.3 | 232.7 ± 165.2 | 290.6 ± 184.0 |
| Sleep duration (hours/day) | 6.75 ± 1.26 | 7.01 ± 1.36 | 7.12 ± 1.65 | 7.66 ± 1.22 | 6.51 ± 1.35 | 7.09 ± 1.16 |
| PSQI | 4.68 ± 2.38 | 5.18 ± 2.56 | 4.92 ± 1.68 | 5.00 ± 1.88 | 5.47 ± 3.46 | 4.17 ± 3.22 |
| ESS | 5.62 ± 3.93 | 5.31 ± 3.40 | 5.50 ± 2.76 | 5.14 ± 3.10 | 6.52 ± 3.79 | 6.47 ± 3.67 |
| Serum serotonin (ng/mL) | 175.1 ± 43.1 | 192.1 ± 54.5 | 125.8 ± 59.2 | 134.4 ± 47.5 | 183.6 ± 40.3 | 168.8 ± 28.3 |
Variable values are presented as mean ± SD.
γ-PGA, poly-γ-glutamic acid; VitB6, vitamin B6; PSQI, Pittsburgh Sleep Quality Index; ESS, Epworth Sleepiness Scale.
*Group A received γ-PGA supplementation only; Group B received VitB6 supplementation only; Group C received both γ-PGA and VitB6 supplementation.