The effect of circadian timing program created for obese individuals with evening chronotype on obesity management and sleep quality

INTRODUCTION AND OBJECTIVE: This study aimed to examine the effect of the circadian timing program created for obese individuals with an evening chronotype on obesity management and sleep quality. MATERIAL AND METHOD: Ethics committee approval was obtained for this study, which was conducted in a randomized controlled experimental design, and registered with ClinicalTrials.gov. The sample of the study consisted of 38 first-degree obese individuals with evening chronotypes, 19 in each study group. The circadian timing program (SIZAP) training developed by the researchers was given to the individuals in the intervention group by the researcher via the research website. Lifestyle changes were provided for the intervention group by SIZAP. The control group followed their normal daily lifestyle. No intervention was made in the dietary practices of both groups. In data collection, "The Horne & Ostberg Morningness-Eveningness Questionnaire", "Personal Information Form", "Anthropometric Measurement Form", "Metabolic Control Variables Form", "Epworth Sleepiness Scale", "Pittsburgh Sleep Quality Index", "Impact of Weight on Quality of Life-Lite Questionnaire", and "a one-week sleep diary" were used. "SIZAP Compliance Form", "Sleep Diary", and "Nutrition Diary" data, which were followed on the Web site, were also collected. Student's t-test, Mann Whitney U test, dependent samples t-test, Wilcoxon t-test, and chi-square test were used to evaluate the data. FINDINGS: It was determined that the intervention group's anthropometric measurements and daytime sleepiness decreased significantly compared to the control group. The sleep quality and bodily functions quality of life dimension increased significantly compared to the control group (p<0.05). CONCLUSION: It has been determined that SIZAP is effective in obesity management in individuals with an evening chronotype, increasing weight loss success and sleep quality. Keywords: chronotype, evening chronotype, obesity, circadian misalignment, sleep quality.