The athlete's sleep paradox prompts us to reconsider the dose-response relationship of physical activity and sleep.

Everyone needs good quality sleep. Good sleep is essential for health, while poor sleep increases morbidity and mortality risk.1 Sleep is also crucial for athletic performance and recovery.2 Even though physical activity (PA) and exercise improve sleep,3 poor sleep is prevalent among elite-level athletes.4 We therefore propose a modified, inverted U-shaped, dose-response relationship between PA and sleep (figure 1), and highlight the need for more research on the PA-sleep dose-response relationship. In this editorial, we briefly discuss the current understanding of the dose-response relationship of PA and sleep, describe the paradox of sleep in athletes, illustrate our hypothetical model, and outline where future research is needed. Figure 1 The dose-response relationship between physical activity (intensity and/or volume) and sleep quality (ie, duration, efficiency, etc) is dependent on physical fitness level. Low physical activity is associated with poorer sleep quality irrespective of fitness level; however, the benefits of physical activity on sleep quality are positive until acute fatigue or overtraining occurs from too much physical activity (either volume and/or intensity). The ‘tipping point’ for when acute fatigue and overtraining occur is dependent on whether an adult has low physical fitness (red), moderate-to-high physical fitness (green) or has elite athlete physical fitness (yellow). Individual, social and mental health factors may also impact sleep positively or negatively. Individual factors include: age, gender, lifestyle (eg, diet and caffeine intake), body mass, among others. …