Diffuse brain injury does not affect chronic sleep patterns in the mouse.

PRIMARY

OBJECTIVE

To test if the current model of diffuse brain injury produces chronic sleep disturbances similar to those reported by TBI patients.

METHODS AND PROCEDURES: Adult male C57BL/6 mice were subjected to moderate midline fluid percussion injury (n = 7; 1.4 atm; 6-10 minutes righting reflex time) or sham injury (n = 5). Sleep-wake activity was measured post-injury using a non-invasive, piezoelectric cage system. Chronic sleep patterns were analysed weekly for increases or decreases in percentage sleep (hypersomnia or insomnia) and changes in bout length (fragmentation).

MAIN OUTCOMES AND

RESULTS

During the first week after diffuse TBI, brain-injured mice exhibited increased mean percentage sleep and mean bout length compared to sham-injured mice. Further analysis indicated the increase in mean percentage sleep occurred during the dark cycle. Injury-induced changes in sleep, however, did not extend beyond the first week post-injury and were not present in weeks 2-5 post-injury.

CONCLUSIONS

Previously, it has been shown that the midline fluid percussion model used in this study immediately increased post-traumatic sleep. The current study extended the timeline of investigation to show that sleep disturbances extended into the first week post-injury, but did not develop into chronic sleep disturbances. However, the clinical prevalence of TBI-related sleep-wake disturbances warrants further experimental investigation.