Reduced Melatonin and Sleep Disruption After Traumatic Brain Injury

Traumatic brain injury (TBI) is often associated with significant sleep fragmentation and excessive daytime somnolence. Shear injuries of the midline ascending projecting aminergic and cholinergic systems contribute to these abnormalities, although the orexin/hypocretin system has also been implicated (Ann Neurol 2009; 66:555). To assess how the circadian neurotransmitter melatonin might also be involved, investigators conducted an observational study of 23 patients at least 6 months after TBI and 23 controls. The researchers used standardized saliva melatonin assays and polysomnography. The timing of melatonin rise (melatonin normally rises at night in dim light) could not be determined in nine patients and nine controls. Participants comp…