Abstract

Shift work is the popular working pattern in many fields in industrialized nations. However, the shift worker
does not pay much attention to his (her) own health. It is known that shift work has strong associations with
various diseases. The aim of this study was to investigate the relationship between food intake and chronotype in
Japanese nurses working an irregular rotation of shifts. This questionnaire-based study used a cross-sectional
design. Participants were nurses working in several hospitals, data from 159 respondents being analyzed. The
questionnaire covered demographics, the Diurnal Type Scale (DTS) and a Food Intake Questionnaire (FIQ). The
DTS scores were classified into three chronotype groups: modified Morning-type (M-type), modified
Evening-type (E-type) and modified Intermediate-type (I-type). For food intake behavior, meal habits of the
M-types were compared with the E-types before / after day- and night-work. In the morning, just after the
night-shift, the M-types chose cold food more frequently (p = .016) and felt less satiated after the meal (p = .016)
than the E-types. Furthermore, the E-types chose significantly larger meals (p = .023) than the M-types, the
M-types snacking more frequently. Chronotype was associated with the food intake behavior both in day- and
night-shift. These results suggest that the Morning-type person suffered more inconvenience with regard to food
intake behavior during night-work.

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