mTBI is trauma to the brain due to a blow or other mechanical force affecting the head. Prior research has established that common symptoms of mTBI include decreased sleep quality and onset/worsening of emotional dysregulation. However, there is little published research investigating how sleep disruption and depressive symptoms are experienced at varying stages of mTBI. We hypothesized that sleep disruption would change with differing time since injury, and that depressive symptoms should accordingly. Additionally, since females tend to have higher rates of depression, we predicted that there would be a significant difference between the sexes at different stages post-mTBI.

This study included 145 healthy adults, split into six groups, comparing healthy controls consisting of 15 males (Mage=23.67, SD=5.066) and 17 females (Mage=25.35, SD=7.035) to individuals who had mTBI, 41 males (Mage=26.88, SD=8.509) and 72 females (Mage=23.79, SD=6.898) at five points post-mTBI: 2 weeks and 1, 3, 6, and 12 months. The Pittsburgh Sleep Quality Index (PSQI) global score was used to assess individual sleep quality and disturbances; higher scores indicated poorer sleep quality. The Beck Depression Index (BDI-II) was used to assess characteristics and symptoms of depression. We adjusted the score to exclude item 16, which measures changes in sleep. Higher scores indicate more severe depressive symptoms. We conducted a multivariate analysis of variance and Pearson correlation to examine whether there were significant differences in sleep and depression at different stages of mTBI for each sex.

We discovered that sleep quality was worse at chronic stages of mTBI (i.e, 12M, p=<.001), than at acute stages (2W, p=.049), and compared to healthy controls. There were also significant differences in depression scores compared to healthy controls at 2W, p=.008, 3M, p=<.001, and 6M, p=.012, but not 12M, p=.313, suggesting that depressive symptoms resolved by 12M in those with mTBI. To explain this, we investigated sex differences, as males tend to experience fewer depressive disorders than females. However, females reported fewer depressive symptoms than males at chronic stages of mTBI. This finding was not statistically significant as females had a Mbdi_total=6.84, SD=7.98 and males had a Mbdi_total=5.38, SD=6.078; still, this could be due to the low statistical power of the study, and with a larger sample size, could produce statistically significant differences between the sexes. Despite this, there is a statistically significant difference in the depression score for females between 2W and 12M post-mTBI (p=.046; effect size of d=.99). Comparatively, males showed no significant divergence between depression and sleep scores.

Sleep disruption and depressive symptoms were correlated in individuals with mTBI in both acute and chronic stages; however, at 12M, there was a decrease in this correlation due to females exhibiting fewer depressive symptoms in combination with greater sleep disruption in the chronic phase of mTBI. Further research investigating the relationship between depression and sleep quality by looking at females with a much larger sample size would be helpful in clarifying these associations.