Physical activity, contact sports and quality of sleep: the good, the bad and the (possibly) ugly.

There is little argument that physical activity is beneficial for one’s health. Indeed, increasing the amount of physical activity is associated with extensive health improvement, mostly in coronary artery disease, hypertension, stroke, insulin sensitivity, osteoporosis, and depression [1–4]. As such, the United States Department of Health and Human Services recommends ‘‘physical activity most days of the week for at least 30 minutes for adults” [5]. Some sports (mainly the ‘‘contact sports”) are, however, associated with various injuries, among which brain concussion, or minor traumatic brain injury (mTBI), is not unusual [6]. Although concussion has traditionally been described as a transient, fully reversible, cerebral dysfunction, this ostensibly mild injury sometimes results in long-lasting and disabling post-concussion symptoms as well as abnormal neuropsychological profiles characteristic of frontal or temporal lobe dysfunction, including some alterations of sleep patterns [7]. The pathological changes following concussion remain unclear, but it is widely thought that concussion results mainly in functional disturbance rather than in structural damage per se [8]. This damage may persist and manifest as some degree of cognitive, emotional and behavioral disturbances even decades after the occurrence of the event [9] We also documented this phenomenon in a mouse model of mTBI [10]. Studying mTBI in a mouse model allows for in-depth and detailed examination of anatomical derangement far beyond that possible in clinical settings. We demonstrated apoptotic process activation in the concussed