Relationship of morningness-eveningness questionnaire score to ferritin, gamma glutamyl- transpeptidase and alanine amino-transferase concentrations in a large cohort

Background :
The circadian rhythms of sleep propensity and melatonin secretion are driven by the suprachiasmatic nuclei (SCN) of the hypothalamus. The liver is also considered as an extra-SCN pacemaker and its biological parameters have proved to follow a circadian pattern of secretion. Only one study in the literature was found to investigate the relation between liver biomarkers and Morningness-Eveningness traits, revealing higher levels of ALAT in evening type patients among diabetic subjects. There is currently no study about whether subjective Morningness-Eveningness correlates with hepatic biomarkers biological rhythm in a large population.

Objective and design :
This retrospective cohort aimed to evaluate the relation between preferred timing of sleep behaviour and selected hepatocellular biological parameters. A large cohort of 6846 subjects from authors’ patients’ clinical records, among which 564 completed both the reduced Morningness-Eveningness questionnaire (MEQ) and blood samples, was used. A multivariate analysis was performed to evaluate the association between chronotypes and these hepatocellular parameters.

Results :
The results found a significant association between low ferritin (p=0.0401), gamma-glutamyl transpeptidase (GGT) (p=0.0173) and alanine aminotransferase (ALAT (p=0.007) levels and the evening chronotypes. Contrary to the previous cited study, ALAT levels were found to be lower for the evening type. Also, the parallel decrease of ALAT, GGT, and ferritin levels from morning to evening chronotypes support the hypothesis of a chronobiological pattern for liver biological parameters. These results would indicate that chronotypes have an important role in the circadian rhythms of hepatocellular function. Furthermore, this study found a significant correlation between the morning chronotypes and the elderly population, well known by now, and between the evening chronotypes and higher fatigue scores.

Keywords :
circadian rhythms, iron, ferritin, haemoglobin, somnolence, depression,
fatigue, hepatocellular biomarkers