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Factors Disrupting Melatonin Secretion Rhythms During Critical Illness
Matthew B Maas1,2, Bryan D Lizza3, Sabra M Abbott1,2
1Department of Neurology, Northwestern University, Chicago, IL.
Critical Care Medicine
|April 23, 2020
Summary
Critically ill patients exhibit disrupted circadian rhythms, particularly with severe encephalopathy and vasopressor use. These disruptions in circadian rhythm and melatonin secretion are not quickly normalized by medical stabilization.
Area of Science:
- Critical care medicine
- Neuroscience
- Endocrinology
Background:
- The circadian system synchronizes physiological processes and tissue-specific functions.
- Disruptions in circadian rhythms are common in critically ill patients, impacting recovery.
- Understanding these disruptions is crucial for managing complex patient conditions.
Purpose of the Study:
- To characterize acute alterations in circadian rhythms among critically ill patients.
- To investigate the relationship between brain dysfunction, organ dysfunction, environmental stimuli, and circadian rhythms.
- To analyze the central circadian rhythm-controlled melatonin secretion profile in intensive care unit (ICU) patients.
Main Methods:
- A prospective study observed 112 critically ill patients (sepsis or intracerebral hemorrhage) for 24-48 hours in specialized ICUs.
- Evaluated environmental exposures (light, feeding, activity, medications) and their impact on circadian rhythms.
- Assessed encephalopathy (Glasgow Coma Scale), organ function (Sequential Organ Failure Assessment score), and melatonin profiles (serum and urinary 6-sulphatoxymelatonin).
Main Results:
- Critically ill patients experienced abnormal environmental exposures, including dim light and mistimed nutrition/arousal.
- Melatonin rhythms were generally preserved in awake patients but dampened and delayed with increased encephalopathy severity.
- Melatonin hypersecretion was linked to vasopressor infusions, while sedatives had no effect; vasopressor changes correlated with melatonin rhythm shifts.
Conclusions:
- Encephalopathy severity and adrenergic agonist (vasopressor) exposure significantly altered melatonin rhythms in critically ill patients.
- Improvements in encephalopathy and medical stabilization did not rapidly restore normal circadian rhythms.
- Urinary 6-sulphatoxymelatonin is an unreliable marker for the central circadian rhythm in critically ill populations.
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