Effect of night work on the hormonal control of hunger and satiety

Author(s)

Daniela Schiavo Cardozo

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2012-11-12

Examining board members

Bruno Geloneze Neto; Maria Cristina Foss de Freitas; Nina Rosa de Castro Musolino; Roberta Soares Lara Cassani; Laura Sterian Ward

• Advisor: Bruno Geloneze Neto

Abstract

Due to the considerable increase of night shift workers it is important the study of its effects on worker health. Recent studies reveal that work in shifts and night shift work propitiate digestive disorders related to differences in dietary habits, in the total caloric content, as well as in the timing and number of meals. Moreover, it is noticed an increase in cardiovascular risk factors such as high levels of triglycerides and cholesterol, and abdominal obesity, insulin resistance and markers of metabolic syndrome. These phenomena are related to gain and redistribution of body weight, in part attributable to changes in the pattern of hunger and satiety. Night shift workers may have endogenous biological rhythm disturbance as a result of the temporal conflict between the endogenous biological clock and the functioning structure of social activities. This asynchronization may produce intense and persistent disorders in sleep physiology. We selected 12 night shift workers and 12 day workers of the HC-UNICAMP, with BMI between 25 and 29.9 (overweight). The objective of this study was to compare a population of night shift workers with a daytime working population in relation to anthropometric and biochemical components of the metabolic syndrome. Besides that, the characterization of the responses of hormones regulating hunger and satiety was accessed by means of a standard meal test , with dosages of ghrelin, oxyntomodulin, xenin, glucagon-like peptide 1 (GLP-1) and PYY3-36. Insulin resistance was evaluated by indexes relating the production of insulin during the glycemic test meal (Stumvol index). These same volunteers were evaluated for the quality of sleep, the chronotype and sub-clinical inflammatory state (assessed by circulating levels of interleukin-6, TNF-?, adiponectin and protein C-reactive). In the assessment for the chronotype, the highest proportion of indifferent individuals were found in the group of night shift. The quality of sleep assessed by pittsburgh score showed no significant difference between groups. The night shift workers showed higher values for daytime dysfunction, demonstrating excessive daytime sleepiness. The main finding was the characterization of a increased response in production of hormone - ghrelin - in the postprandial period of night shift workers and reduced response of xenina (an anorectic hormone source and stomach). As a conclusion, this fact may be responsible for the weight gain observed for those night shift workers. (AU)