There is rising concern over the potential cumulative and long-lasting effects of prior concussions in active and retired athletes. Previous studies suggest that there is an inverse relationship between concussion (or mild traumatic brain injury) and sleep, with increasing evidence of individuals reporting chronically disrupted sleep following remote concussion. The extent to which these effects are cumulative across repeat concussions is unknown. This project aimed to investigate the association between the number of prior concussions and subjective sleep quality in otherwise healthy collegiate-aged athletes. Furthermore, we investigated which aspects of sleep are most associated with prior concussion.

A total of 176 collegiate-aged athletes (Mage = 21.19, SD = 1.63; 65.9% men) completed off-season clinical visits, at least 6 months since their most recent concussion. Semi-structured interviews captured detailed sport and head injury history across the lifespan. The number of prior concussions for each participant was retrospectively assessed based on American Congress of Rehabilitation Medicine criteria. Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). A general linear model tested the relationship between number of prior concussions and global PSQI score (i.e., overall sleep quality). Logistic regression models were fit to investigate the association of the number of prior concussions with individual subcomponents of the PSQI (i.e., quality, latency, duration, efficiency, disturbances, use of sleep medications, and daily dysfunction), which were binarized based on their distribution. Sex and total number of years of exposure to contact sports were included as covariates for all models.

The number of prior concussions was significantly associated with worse overall sleep quality as assessed by the global PSQI score, F(3,172)=6.92, p= <0.001, unstandardized beta[B](standard error[SE])=0.54(0.14). Investigation of sub-components showed that the number of prior concussions was significantly associated with multiple PSQI subcomponents, including: poorer sleep quality, odds ratio [OR]=1.35, 95% CI [1.05, 1.74], p=0.02; longer sleep latency, OR=1.35, 95% CI [1.08, 1.68], p=0.008; more sleep disturbances, OR=1.56, 95% CI [1.15, 2.12], p=0.004; and more sleep-related daily dysfunction, OR=1.46, 95% CI [1.16, 1.83], p=0.001. The number of prior concussions was not significantly associated with sleep duration, sleep efficiency, or the use of sleep medication (ps>0.05). There were no years of exposure effects (ps>0.05). Select sex-related effects on sleep quality were observed. Specifically, women reported significantly worse global sleep scores, F(3,172)=6.92, p=0.048, B(SE)=-0.99(0.50), and women reported significantly more sleep disturbances, B(SE)=1.47(0.70), p=0.04, OR=4.34 (95% CI [1.11, 16.98].

These results suggest a potential dose-effect of concussion history on poorer sleep quality ratings in otherwise healthy athletes. Specific facets of sleep that were adversely associated with prior concussion included sleep quality, latency, disturbances, and daily dysfunction, highlighting potential areas for sleep-related clinical interventions. Given the adverse effects of chronic sleep disturbance on mental health, future studies are needed to determine the role of concussion-related sleep problems in the adverse psychological outcomes observed in some athletes with multiple prior concussions.