Studies focusing on effects of sleep on physical performance respectively running are sparse. In the younger past knowledge evoked that sleep debt has many effects on dietary intake and predisposes adiposity or diabetes. It is suggested that the current obesity epidemic is also caused by sleep dept which influences endocrine homeostasis (Leptin, Ghrelin, Neuropeptide Y, galanin, orexin, and insulin homeostasis) and affects eating behavior in consequence. Especially glucose homeostasis is strongly coupled with endurance capacity respectively running performance. Sleep debt goes in with a dysregulation of the Melatonin system affecting ACTH-Cortisol Homeostasis while having effects on running performance. Running has positive effects on sleep quality but the counter mechanism that good sleep improves running performance is only partly elucidated. However, sufficient sleep is of highest importance for improving personal best times and hard training days are only possible with adequate sleep. When looking forward newest findings indicate that hard training days go in with a reduced sleep efficiency underlying the complex mechanism remaining to be elucidated.