Systematic review of melatonin levels in individuals with complete cervical spinal cord injury

The Journal of Spinal Cord Medicine, 2020 · DOI: 10.1080/10790268.2018.1505312 · Published: October 2, 2020

Spinal Cord Injury Endocrinology Physiology

Simple Explanation

This systematic review examines melatonin levels in individuals with complete cervical spinal cord injury (SCI). Melatonin, a hormone produced by the pineal gland, is crucial for regulating sleep-wake cycles and other bodily functions. The study compares melatonin profiles in individuals with complete cervical SCI to those of healthy controls and individuals with incomplete cervical SCI and thoracolumbar SCI. The review also investigates the impact of injury chronicity and melatonin supplementation on melatonin levels in adults with complete cervical SCI, exploring both sleep and non-sleep related outcomes.

Study Duration

January 1978 to August 2017

Participants

130 individuals with SCI

Evidence Level

Systematic Review

Key Findings

1
Adults with complete cervical SCI tend to have absent diurnal melatonin rhythms compared to healthy controls and individuals with thoracolumbar SCI below T3.
2
There is limited evidence comparing melatonin levels in individuals with complete cervical SCI to those with incomplete tetraplegia.
3
Based on limited studies, melatonin supplementation does not appear to significantly improve sleep outcomes in adults with long-standing complete cervical SCI.

Research Summary

This systematic review aimed to evaluate melatonin levels in individuals with complete cervical SCI compared to healthy controls and those with other types of SCI. The review analyzed 12 studies to assess melatonin profiles, injury chronicity, and the impact of melatonin supplementation. The findings suggest that individuals with complete cervical SCI often have reduced night-time melatonin levels and absent circadian rhythms compared to healthy controls and those with thoracolumbar SCI. The evidence comparing complete and incomplete cervical SCI is limited. Melatonin supplementation does not consistently improve sleep outcomes in adults with chronic complete cervical SCI, and more research is needed to understand its impact on non-sleep outcomes like cardiovascular health and neurological recovery.

Practical Implications

Further research on acute SCI

Future studies should focus on understanding melatonin levels in the acute phase after cervical SCI to optimize the timing of melatonin supplementation trials.

Investigate non-sleep outcomes

Additional research is needed to explore the potential benefits of melatonin supplementation on non-sleep outcomes, such as cardiovascular health, pain management, and neurological recovery in individuals with complete cervical SCI.

Refine melatonin supplementation protocols

Future studies should use comprehensive measurement protocols to evaluate the impact of melatonin supplementation on circadian rhythm and individual pharmacokinetic responses, potentially leading to personalized treatment strategies.

Study Limitations

1
Heterogeneity in study designs limited quantitative analysis, resulting in a narrative analysis.
2
Inclusion of conference proceedings and abstracts with less robust data.
3
Lack of controlled light conditions and infrequent melatonin measurements in some studies.

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