The influence of sleep and mood on cognitive functioning among veterans being evaluated for mild traumatic brain injury.

OBJECTIVE: Veterans undergoing evaluation for mild traumatic brain injury commonly report insomnia, psychiatric symptoms, and cognitive dysfunction. This study examines the effects of self-reported amount of sleep and subjective sleep quality on neuropsychological test performance.

METHOD: 262 veterans were seen for neuropsychological assessment in a Veterans Affairs traumatic brain injury clinic. All participants completed measures of depression, anxiety, and sleep satisfaction, and also estimated the number of hours they slept the night before the assessment. Factor scores of attention/concentration and memory were created using factor analyses. Data were analyzed with linear regression.

RESULTS: Depression and anxiety were significantly correlated with sleep satisfaction and predictive of cognitive ability. Both sleep satisfaction and hours slept were significantly correlated with memory, but not attention. After controlling for the effects of depression and anxiety, hours slept but not sleep satisfaction was predictive of memory test performance.

CONCLUSIONS: Perceived sleep quality is heavily influenced by psychiatric symptoms; therefore, veterans' report of sleep satisfaction may merely reflect their overall level of distress. Sleep quantity, however, appears to uniquely contribute to memory performance. Thus, assessment of sleep is important and provides clinicians with useful information, especially among individuals with psychiatric comorbidities.