Reduced Melatonin Associated with Sleep Disturbance in Traumatic Brain Injury

A new study suggests that increased slow wave sleep is attributed to the effects traumatic brain injury (TBI), and is possibly related to significantly lower levels of evening melatonin production.

Researchers at Monash University (Melbourne, Australia) conducted an observational study to investigate sleep-wake disturbances and their underlying mechanisms in 23 patients with TBI and 23 age- and gender-matched healthy volunteers. Study participants were compared on polysomnographic sleep measures, salivary dim light melatonin onset (DLMO) time, and self-reported sleep quality, anxiety, and depression.

The results showed that the patients with TBI reported higher anxiety, depressive symptoms, and sleep disturbance than controls. Although no significant group differences were found in sleep architecture, when anxiety and depression scores were controlled, patients with TBI showed higher amount of slow wave sleep. Patients with TBI also showed decreased sleep efficiency (SE) and increased wake after sleep onset (WASO), but no differences in self-reported sleep timing or salivary DLMO time were found. However, the researchers found that patients with TBI showed significantly lower levels of evening melatonin production, and melatonin level was significantly correlated with REM sleep, but not SE or WASO, indicating that reduced evening melatonin production could be a result of disruption to the circadian regulation of melatonin synthesis. The study was published in the May 25, 2010, issue of Neurology.

""These results suggest that the brain injury may disrupt the brain structures that regulate sleep, including the production of melatonin. We propose that elevated depression is associated with reduced sleep quality, and increased slow wave sleep is attributed to the effects of mechanical brain damage,” said senior corresponding author Shantha Rajaratnam, Ph.D., and colleagues of the school of psychology and psychiatry. "Future studies should examine whether taking supplemental melatonin can improve sleep in people with brain injuries.”

Melatonin (N-acetyl-5-methoxytryptamine), is a naturally occurring compound found in animals, plants, and microbes. In animals, circulating levels of melatonin vary in a daily cycle, thereby regulating the circadian rhythms of several biological functions. Many biological effects of melatonin are produced through activation of melatonin receptors, while others are due to its role as a pervasive and powerful antioxidant, with a particular role in the protection of nuclear and mitochondrial DNA.

Related Links:
Monash University