Chronotype, social jetlag and sleep debt are associated with dietary intake among Brazilian undergraduate students.

Undergraduate students experience a form of circadian misalignment - known as "social jetlag" - that represents the discrepancy in timing between their circadian and social clocks. Whilst social jetlag is not dependent upon chronotype, the two phenomena tend to be related; evening types show a tendency to have a greater social jetlag, for example. Moreover, evening types have been found to be more likely to have inadequate eating habits than do morning types. The objective of this study was to examine the relationship between chronotype, social jetlag, perceived sleep debt and dietary intake in Brazilian undergraduate students. The chronotype was derived from mid-sleep time on free days (MSF) at the weekend. Social jetlag was calculated as the absolute difference between mid-sleep time on weekdays and weekends. Perceived sleep debt was calculated using the difference between students' preferred weekday sleep duration and their self-reported actual weekday sleep duration. Correlations were found between chronotype and breakfast time (r = 0.24, p = 0.003) and lunch time (r = 0.19, p = 0.01). Multiple regression analyses showed that chronotype was positively associated with consumption of meat (ß = 0.21; p = 0.003); social jetlag was negatively associated with consumption of beans (ß = -0.16; p = 0.02) and perceived sleep debt was positively associated with consumption of beverages (ß = 0.15; p = 0.02) and dairy products (ß = 0.17; p = 0.01) and negatively associated with consumption of cereals and pasta (ß = -0.16; p = 0.02). It is concluded that, in undergraduate students, chronotype (MSF), social jetlag and perceived sleep debt can influence the type and amount of some food groups consumed at mealtimes.

Nutritional status and eating habits of bus drivers during the day and night.

The aim of this study was to compare anthropometry and food intake patterns in bus drivers working during the day and night. One hundred and fifty males (81 night workers and 69 day workers) participated in the study. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. Measurements of height, weight, waist circumference (WC), systolic and diastolic blood pressure, blood glucose, and lipid profile were obtained. A significant difference between groups was observed for mean WC (98.5 ± 10.7 cm in day workers versus 103.2 ± 9.7 cm in night workers; p = 0.005). Night workers had higher prevalence of being overweight and obese (BMI ≥ 25 kg/m(2)) than day workers (78.2% day workers versus 90.2% night workers; p = 0.004) and increased WC (>94 cm) (72.4% day workers versus 86.4% night workers; p = 0.03). Significant differences were found for meat consumption (2.3 servings ±0.9 for night workers versus 2.0 servings ±0.7 day workers, p = 0.04) and fruit intake (0.9 servings ±0.4 for night workers versus 0.7 servings for day workers ±0.5; p = 0.006). Night workers had a lower intake of vegetables than recommended compared to day workers (100 versus 92.7%, respectively, p = 0.01) and higher intake of oil (40.7 versus 24.6%, p = 0.03). Multivariate logistic regression analysis indicated that night work was associated with being overweight (OR = 2.94, 95% IC: 1.14-7.66, p = 0.03) and abnormal values of WC (OR = 2.82, 95% IC: 1.20-6.69, p = 0.009) after adjusting for potential confounders. It is concluded that night workers had a higher prevalence and risk of being overweight/obese and increased WC compared with day workers. Night workers also presented a higher proportion of inappropriate intakes of food groups when compared to day workers, even though both groups were eating poor diets. These results demonstrate the need of lifestyle-intervention programs in these workers.