Melatonin Secretion and Sleep Quality in Spinal Cord Injury Patients

Melatonin is a neurohormone secreted by the pineal gland and excreted by the urinary tract. It has a key role in the synchronisation of circadian rhythms including the sleep wake cycle, with a peak secretion around 03:00.

The neural pathway controlling melatonin secretion is long and transits via the thoracic spine. The exact level is not known, but interruption of the connection in patients with lesions of the spinal cord is known to occur.

Tetraplegic patients often complain of insomnia, daytime sleepiness and poor sleep quality but the contribution of melatonin levels to sleep quality has not been explored in large studies, although case reports have shown reduced or abolished melatonin secretion and altered melatonin secretion profiles with delayed peak secretion. Paraplegic patients report fewer sleep difficulties and little is known about melatonin secretion in this group. The investigators hypothesize that sleep abnormalities are related to abnormalities in melatonin secretion and that this is in turn related to the level of the spinal cord injury

The study aims to explore the profiles of melatonin secretion in patients with spinal cord injuries and comparing melatonin profiles with a database of healthy volunteers. The investigators will further analyse the results looking at the severity of spinal cord injury using the Abbreviated Injury Scale (AIS) and the level of the injury. Outcome measures are melatonin secretion profile, sleep complaints measured using the Pittsburgh scale and daytime sleepiness measured using the Epworth sleep scale.