Circadian rhythm sleep disorders following mild traumatic brain injury

OBJECTIVE: To describe the physiologic and behavioral characteristics of circadian rhythm sleep disorders (CRSDs) following minor traumatic brain injury (mTBI) in patients complaining of insomnia. METHODS: Forty two patients with insomnia complaints following mTBI were screened. Those suspected of having CRSD underwent actigraphy, saliva melatonin and oral temperature measurement, and polysomnography. All patients also filled out a self-reported questionnaire to determine their circadian preference. RESULTS: Fifteen of the 42 patients (36%) with complaints of insomnia following mTBI were diagnosed with CRSD. Eight patients displayed a delayed sleep phase syndrome (DSPS), whereas seven displayed an irregular sleep-wake pattern (ISWP). Whereas all patients with DSPS exhibited a 24-hour periodicity of oral temperature rhythm, three of seven patients with ISWP lacked such a daily rhythm. In addition, ISWP patients exhibited smaller amplitude of oral temperature rhythm vs the DSPS group. Subjective Morningness-Eveningness Questionnaire scores were in accordance with the clinical diagnosis of DSPS or ISWP based on actigraphy. CONCLUSIONS: Minor traumatic brain injury might contribute to the emergence of circadian rhythm sleep disorders. Two types of these disorders were observed: delayed sleep phase syndrome and irregular sleep-wake pattern. The types differed in the subjective questionnaire scores and had distinct profiles of melatonin and temperature circadian rhythms.