 The purpose of this investigation is to assess in a community-based cohort of late-night eaters the effect of coincident food intake and endogenous melatonin on glycemic control, and the putative interaction effect of melatonin receptor 1B MTNR1B genetic variation on this relationship. With the results from this study, the investigators expect to advance in the understanding of the role of endogenous melatonin on glucose metabolism in late night eaters and carriers of the MTNR1B risk allele, with potential implications on the guidelines to mitigate risk of type 2 diabetes in late night eaters and carriers of the MTNR1B risk allele. 