We evaluated the eating pattern, physical activity, and daytime sleepiness level in Chilean shift workers. Fifty, middle-aged adult health workers from a public hospital in Santiago, Chile, were included: a group undergoing shift work (shift workers, including at least one “night shift” and one “long day”, n = 33), and day workers under traditional schedule (from 8:00 to 17:00h, n = 17). Body composition, physical activity, and daytime sleepiness levels, and diet characteristics (diet composition, meals' timing, and diet quality) were assessed. Despite similar total energy intake, shift worker showed lower carbohydrate (% of energy) and higher protein intake (both P < 0.01), decreased diet quality, an irregular eating pattern, and delayed meal timing (all P < 0.05). Physical activity and daytime sleepiness levels did not differ between groups. Findings from this first Chilean study in healthcare shift workers support the fact that meal timing and diet quality appear as critical factors for upcoming intervention studies in this group.

In mammals, the biological clock is driven by circadian rhythms, a particular type of biological rhythm that last about 24 hours. There is a close relationship between the functioning of the circadian system, eating and metabolic regulation, which is currently an area of intense research. Alteration of circadian rhythmicity from genetic, behavioral or dietary modifications, leads to behavioral and metabolic disorders, and excessive weight gain. Factors that contribute to circadian disruption include, among others, jet lag, shift work, mistimed and restricted sleep, and irregular eating patterns. This review summarizes the evidence regarding the influence of circadian rhythms on eating processes and the metabolic consequences of circadian disruption. Special focus is on the consequences of disruption of regular eatingfasting and sleep-wake rhythms, and relationships with excessive weight gain, obesity and obesity-related metabolic disorders that are highly prevalent in westernized societies.

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