Concussions are often neglected injuries that affect children and adolescents. Two physiological responses to a concussion are an ionic flux and an increased indiscriminate release of glutamate, which leads to an increase of intracellular calcium and extracellular potassium. This can ultimately result in sleep dysfunction, which often occurs after concussion and has long been thought of as simply another concussion symptom.
Does the likelihood of prolonged postconcussion symptoms increase with reported sleep-related problems (SRPs) in young athletes (8-18 y) compared to concussed young athletes without SRPs and healthy controls?
Four cohort studies with level 2/3 evidence measured subjective and objective sleep dysregulations in concussed and healthy populations. Overall, there was a difference in subjective SRPs between concussed and healthy patients. This correlated with other studies where worse sleep scores during the acute phase of concussion and increased SRPs led to worse ImPACT scores in patients 3 to 12 months postconcussion and longer overall recovery. Objective sleep dysfunction measures were significantly worse in concussed patients than in healthy controls, but no significant difference existed in melatonin measures.
There is strong evidence that sleep dysfunction is both a symptom of concussion as well as a causal factor of prolonged postconcussion symptoms. These studies show that sleep dysregulation is not always evident in objective measurements, leading to the strong possibility of a functional dysregulation of the sleep-wake cycle that is evident solely from subjective reports.
While there are strong cohort studies researching the role of sleep in those with postconcussion symptoms, the nature of sleep studies prevents the production of strong, high-level evidence studies such as randomized control trials. Thus, there is level B evidence that the likelihood of prolonged postconcussion symptoms is increased by a higher amount of SRPs.