Description

Chronotype reflects individuals’ preferred time of day for sleep/activity. Studies suggest that compared to morning chronotypes (MC; preference for early sleep), evening chronotypes (EC; preference for early sleep) engage in poor diet intake, leading to adverse health effects. While greater sensitivity to food smells increase food intake, how odor perception may influence diet intake in EC is unknown. This study aims to determine whether EC perceives food doors to be more intense, and if that relates to poor diet. Fasting EC and MC (determined by Morningness-Eveningness Questionnaire) completed the Smell Identification Test and Sniffin’ Sticks task to determine olfactory function, and rated the intensity of food (strawberry, S) and non-food (rose, R) odors at same time of the day (11am-12pm). Food and non-food odors were bifurcated into high and low intensities: strawberry high (SH), strawberry low (SL), rose high (RH), and rose low (RL). Participants completed food cravings questionnaires and a 3-day food diary. Healthy weight adults participated in the study (ECn=19, age 23.80, BMI 21.79 kg/m2; MC (n=18, age of 24.11, BMI 22.63 kg/m2). No difference in olfactory function was reported between MC (33.06 ± 2.88) and EC (33.84 ± 2.09). Independent of S and R categorization, higher intensity odors were perceived as more intense in EC vs. MC (p <0.003). These results were primarily driven by SH (R2 = 0.41, p <0.004). For every unit increase in odor intensity ratings, overall cravings scores were reported 17 points higher in EC vs. MC (p<0.001). Interestingly, MC reported higher ratings for hunger (p = 0.010), desire to eat (p = 0.027), ability to eat (p = 0.015), and greater cravings for fruits (p = 0.029) and vegetables (p = 0.030). EC also reported higher intake of total calories and carbohydrates later during the day (after 8:00 pm). Our findings suggest that chronotype may influence perceived intensity of food odors enhancing cravings for unhealthy foods.