Figure 3

Linear and non-linear associations between sleep duration and psychological variables. Fitted lines and curves as well as their 95% confidence intervals were added. The association of sleep duration with (a) fatigue state, (b) novelty seeking, (c) reward dependence, (d) persistence, (e) self-directedness, (f) cooperativeness, (g) self-transcendence, and (h) Stroop interference.