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 (β = 0.21; p = 0.003); social jetlag was negatively associated with consumption of beans (β = -0.16; p = 0.02) and perceived sleep debt was positively associated with consumption of beverages (β = 0.15; p = 0.02) and dairy products (β = 0.17; p = 0.01) and negatively associated with consumption of cereals and pasta (β = -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.
