## 3 Results  
The results of the Wilcoxon test indicated non-significant differences between caffeine and placebo conditions on average (121 \(\pm\) 11 vs. 124 \(\pm\) 8, respectively; \(p\) = 0.29), as well as maximum heart rate during the randori training sessions (188 \(\pm\) 8 vs. 187 \(\pm\) 8, respectively; \(p\) = 0.34). Similarly, paired T-tests showed non-significant differences in RPE between caffeine and placebo conditions (6.0 \(\pm\) 0.7 vs. 5.8 \(\pm\) 1.5, respectively; \(p\) = 0.68). During the placebo condition, nobody reported side effects, while during the caffeine condition, one participant indicated gastrointestinal problems, tachycardia, and heart palpitations. When evaluated pre-exercise, 67% of the participants identified the caffeine and placebo trials. When evaluated post-exercise, 67% and 78% of the participants identified the caffeine and placebo trials, respectively. Despite apparent differences in mean values between placebo and caffeine in the actigraphy-derived sleep measures, no significant differences were observed (\(p>0.05\) for all, Table 2). Small effect sizes were observed for almost all actigraphy-derived sleep measures (ES = 0.20-0.44), except \"wake after sleep onset\". Additionally, no significant differences in heart rate during the night were observed between placebo and caffeine conditions (56 \(\pm\) 5 vs. 54 \(\pm\) 5, respectively; \(p\) = 0.47). One significant difference between the conditions was found, favoring placebo in sleep quality reported in the Karolinska Sleep Questionnaires (\(p\) = 0.03; ES = 1.09) (Table 2), without significant differences in other parameters (\(p\) > 0.05 for all). However, small (ES = 0.21-0.41) and large (ES = 0.88) ESs were noted for all subjective sleep quality measures, except for \"feeling refreshed after awakening\". No significant differences (\(p>0.05\) for all) were indicated in the results of the short recovery and stress scale between caffeine and placebo conditions. Small effect sizes \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Actigraphic Sleep Quality** & **Placebo** & **Caffeine** & \(Z\) & \(p\) & **ES (95\% CI)** \\ \hline Sleep duration (h) & \(7.1\pm 1.4\) & \(6.6\pm 0.8\) & \(0.65\) & \(0.51\) & \(-0.44\) (\(-0.52\), \(1.35\)) \\ \hline Time in bed (h) & \(8.2\pm 1.4\) & \(7.7\pm 0.8\) & \(0.17\) & \(0.85\) & \(-0.44\) (\(-1.35\), \(0.52\)) \\ \hline Sleep efficiency (\%) & \(87\pm 6\) & \(85\pm 7\) & \(0.56\) & \(0.55\) & \(-0.31\) (\(-1.22\), \(0.64\)) \\ \hline Wake after sleep onset (min) & \(64\pm 25\) & \(68\pm 25\) & \(0.06\) & \(0.95\) & \(0.16\) (\(-0.77\), \(1.08\)) \\ \hline Number of awakenings (n) & \(18\pm 4\) & \(17\pm 5\) & \(12.5\) & \(0.43\) & \(-0.20\) (\(-1.12\), \(0.74\)) \\ \hline Time between substance intake and & \(325\pm 37\) & \(345\pm 63\) & \(0.77\) & \(0.44\) & \(-0.39\) (\(-0.56\), \(1.30\)) \\ \hline
**Karolinska Sleep Questionnaire** & & & & & \\ \hline Sleep Quality & \(3.9\pm 0.6\) & \(3.0\pm 1.0\) & \(2.20\) & \(0.03\) * & \(-1.09\) (\(-2.02\), \(0.06\)) \\ \hline Calm sleep & \(3.6\pm 1.4\) & \(3.0\pm 1.7\) & \(1.48\) & \(0.14\) & \(-0.39\) (\(-1.30\), \(0.56\)) \\ \hline Easy of falling asleep & \(4.3\pm 0.9\) & \(3.1\pm 1.7\) & \(1.69\) & \(0.09\) & \(-0.88\) (\(-1.80\), \(0.12\)) \\ \hline Amount of dreaming & \(4.9\pm 0.3\) & \(4.6\pm 1.0\) & \(0.80\) & \(0.42\) & \(-0.41\) (\(-1.32\), \(0.55\)) \\ \hline Ease of waking up & \(4.0\pm 1.5\) & \(4.3\pm 1.3\) & \(0.26\) & \(0.79\) & \(0.21\) (\(-0.72\), \(1.13\)) \\ \hline Feeling refreshed after awakening & \(3.1\pm 1.4\) & \(2.9\pm 1.6\) & \(0.53\) & \(0.59\) & \(-0.13\) (\(-1.05\), \(0.80\)) \\ \hline \hline \end{tabular}
\begin{tabular}{l c c c c} \hline \hline \multicolumn{4}{c}{Data reported as mean \(\pm\) standard deviation. Z: Wilcoxon pairwise order test result; *: statistically difference} \\ \multicolumn{4}{c}{from placebo at \(p<0.05\).} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Sleep quality measures for caffeine and placebo conditions.