Table 2. Subjective sleepiness and perceptive fatigue in Nap and No-nap condition Nap No nap p Cohen’s d KSS 5.21 ± 1.69 5.57 ± 1.45 0.679 0.25 VAS 5.64 ± 1.45 6.64 ± 2.17 0.073 0.46 KSS, Karolinska Sleepiness Scale; VAS, Visual Analogue Scale (self-perceived fatigue). Mean values for the Nap versus No nap values were compared using a paired t-test.