Mistimed food intake and sleep alters 24-hour time-of-day patterns of the human plasma proteome.

Proteomics holds great promise for understanding human physiology, developing health biomarkers, and precision medicine. However, how much the plasma proteome varies with time of day and is regulated by the master circadian suprachiasmatic nucleus brain clock, assessed here by the melatonin rhythm, is largely unknown. Here, we assessed 24-h time-of-day patterns of human plasma proteins in six healthy men during daytime food intake and nighttime sleep in phase with the endogenous circadian clock (i.e., circadian alignment) versus daytime sleep and nighttime food intake out of phase with the endogenous circadian clock (i.e., circadian misalignment induced by simulated nightshift work). We identified 24-h time-of-day patterns in 573 of 1,129 proteins analyzed, with 30 proteins showing strong regulation by the circadian cycle. Relative to circadian alignment, the average abundance and/or 24-h time-of-day patterns of 127 proteins were altered during circadian misalignment. Altered proteins were associated with biological pathways involved in immune function, metabolism, and cancer. Of the 30 circadian-regulated proteins, the majority peaked between 1400 hours and 2100 hours, and these 30 proteins were associated with basic pathways involved in extracellular matrix organization, tyrosine kinase signaling, and signaling by receptor tyrosine-protein kinase erbB-2. Furthermore, circadian misalignment altered multiple proteins known to regulate glucose homeostasis and/or energy metabolism, with implications for altered metabolic physiology. Our findings demonstrate the circadian clock, the behavioral wake-sleep/food intake-fasting cycle, and interactions between these processes regulate 24-h time-of-day patterns of human plasma proteins and help identify mechanisms of circadian misalignment that may contribute to metabolic dysregulation.

Impact of circadian misalignment on energy metabolism during simulated nightshift work.

Eating at a time when the internal circadian clock promotes sleep is a novel risk factor for weight gain and obesity, yet little is known about mechanisms by which circadian misalignment leads to metabolic dysregulation in humans. We studied 14 adults in a 6-d inpatient simulated shiftwork protocol and quantified changes in energy expenditure, macronutrient utilization, appetitive hormones, sleep, and circadian phase during day versus nightshift work. We found that total daily energy expenditure increased by ∼4% on the transition day to the first nightshift, which consisted of an afternoon nap and extended wakefulness, whereas total daily energy expenditure decreased by ∼3% on each of the second and third nightshift days, which consisted of daytime sleep followed by afternoon and nighttime wakefulness. Contrary to expectations, energy expenditure decreased by ∼12-16% during scheduled daytime sleep opportunities despite disturbed sleep. The thermic effect of feeding also decreased in response to a late dinner on the first nightshift. Total daily fat utilization increased on the first and second nightshift days, contrary to expectations, and carbohydrate and protein utilization were reduced on the second nightshift day. Ratings of hunger were decreased during nightshift days despite decreases in 24-h levels of the satiety hormones leptin and peptide-YY. Findings suggest that reduced total daily energy expenditure during nightshift schedules and reduced energy expenditure in response to dinner represent contributing mechanisms by which humans working and eating during the biological night, when the circadian clock is promoting sleep, may increase the risk of weight gain and obesity.

The factors influencing the eating behaviour of shiftworkers: what, when, where and why.

Shiftwork leads to altered eating patterns, with workers often eating foods at all times across the 24 h period. Strategies to reduce the burden of shiftwork on the workers should be prioritised and altering these eating patterns is an important area for change. This narrative review examines the current evidence on the individual and environmental factors influencing the eating behaviours of shiftworkers. A systematic search was conducted and yielded 62 articles. These were split into four themes that influence eating patterns; When shiftworkers eat, What type of foods shiftworkers eat, Where the food is sourced from, and Why shiftworkers choose to eat on shift. Irregular working hours was the biggest influence on when workers ate on shift, shift-type was the biggest influence on what workers ate, the majority of food was sourced from canteens and cafeterias, and socialising with colleagues was the biggest reason why workers chose to eat. While more research is needed to explore multiple industries and shift-types, and to investigate the ideal size, type and timing of food on shift, this review has highlighted that future research into shiftworker eating needs to adopt an integrative approach and consider the different individual and social contexts that influence eating patterns.

Caloric midpoint is associated with total calorie and macronutrient intake and body mass index in undergraduate students.

Studies have suggested that eating at later times may be a risk factor for being overweight. The aim of this study was to investigate the association of caloric midpoint on the anthropometric profile and calorie and macronutrient intake during the day. The study included 718 Brazilian undergraduate students (20.5 ± 2.9 years old; 67% women). Dietary intake was assessed by 24-h recall and the diurnal variation of calorie consumption was evaluated by caloric midpoint average time at which 50% of daily energy were consumed. Participants were classified into two groups according to caloric midpoint median; early eaters (caloric midpoint ≤ 3:00 pm) or late eaters (caloric midpoint > 3:00 pm). Body weight and waist circumference were measured and body mass index (BMI) was determined. Generalized linear models adjusted for confounding variables were used to determine the association between variables. The late eaters presented higher BMI when compared to early eaters (23.0 kg/m2 ± 0.3 vs. 22.1 kg/m2 ± 0.2, respectively; p = .02). Late eaters reported a higher total daily consumption of energy (p < .001) and proportion consumed after 9:00 pm (p < .001), as well as total daily carbohydrate (p < .001), protein (p < .001), fat (p < .001), saturated fat (p < .001), and cholesterol (p = .04) intake when compared with early eaters. We conclude that concentrating food intake later in the day is associated with higher total energy and macronutrient intake as well as a higher average BMI.

Insomnia in Pregnancy Is Associated With Depressive Symptoms and Eating at Night.

STUDY OBJECTIVES: Deterioration in sleep quality seems to be a natural consequence of physical changes during pregnancy. It is still unclear if insomnia in pregnancy is associated with the same factors as chronic insomnia in the general population. The aim of this study was to explore the determinants of insomnia during pregnancy. METHODS: The study included 266 women (mean age: 30.6 ± 5 years, weeks of pregnancy: 36 [interquartile range 32-38]) recruited at the Department of Gynecology and Obstetrics, Medical University of Warsaw. The assessment of variables was performed using the Athens Insomnia Scale (AIS), Beck Depression Inventory (BDI), Regestein Hyperarousal Scale (HS), Epworth Sleepiness Scale (ESS), General Practice Physical Activity Questionnaire, and a semi-structured interview about different sleep disorders. RESULTS: Almost 40% of the women in our study received a diagnosis of insomnia based on AIS cutoff scores. The between-group analyses indicated that HS score, BDI score, eating at night, legs tingling, nightmares, snoring, and myoclonus differentiated the groups of individuals with insomnia from those without insomnia. Other variables were not significantly different between the groups. We divided individuals with insomnia in terms of insomnia duration: 49% developed insomnia at least 1 year before the study onset and 39.6% during pregnancy. For further analyses we used only the women in whom insomnia developed during pregnancy. Logistic regression confirmed that depressive symptoms (BDI) and eating at night were significant predictors of insomnia in pregnancy. CONCLUSIONS: Depressive symptoms and night eating are key factors related to insomnia developed during pregnancy.

It's not just what you eat but when: The impact of eating a meal during simulated shift work on driving performance.

Shiftworkers have impaired performance when driving at night and they also alter their eating patterns during nightshifts. However, it is unknown whether driving at night is influenced by the timing of eating. This study aims to explore the effects of timing of eating on simulated driving performance across four simulated nightshifts. Healthy, non-shiftworking males aged 18-35 years (n = 10) were allocated to either an eating at night (n = 5) or no eating at night (n = 5) condition. During the simulated nightshifts at 1730, 2030 and 0300 h, participants performed a 40-min driving simulation, 3-min Psychomotor Vigilance Task (PVT-B), and recorded their ratings of sleepiness on a subjective scale. Participants had a 6-h sleep opportunity during the day (1000-1600 h). Total 24-h food intake was consistent across groups; however, those in the eating at night condition ate a large meal (30% of 24-h intake) during the nightshift at 0130 h. It was found that participants in both conditions experienced increased sleepiness and PVT-B impairments at 0300 h compared to 1730 and 2030 h (p < 0.001). Further, at 0300 h, those in the eating condition displayed a significant decrease in time spent in the safe zone (p < 0.05; percentage of time within 10 km/h of the speed limit and 0.8 m of the centre of the lane) and significant increases in speed variability (p < 0.001), subjective sleepiness (p < 0.01) and number of crashes (p < 0.01) compared to those in the no eating condition. Results suggest that, for optimal performance, shiftworkers should consider restricting food intake during the night.

Sex Differences in Relationship between Stress Responses and Lifestyle in Japanese Workers.

BACKGROUND: This study examined the relationships between stress responses and lifestyle, including sleeping and eating behaviors, in Japanese workers according to sex. METHODS: Questionnaires about stress responses and lifestyle were completed by 3,017 workers in a financial enterprise (41.5% men, 58.5% women). Data were collected in Japan in August 2011. Participants were classified into stress and nonstress groups. Relationships between stress responses and lifestyle were investigated using logistic regression analysis with stress response as a dependent variable. RESULTS: There were 254 (8.4%) participants in the stress group and 2,763 (91.6%) in the nonstress group. The results showed that sleeping for shorter periods [odds ratio (OR) = 2.97, 95% confidence interval (CI): 1.58-5.60] was associated with stress responses in women, whereas we found no relationship between stress responses and lifestyle among men. However, working overtime was associated with stress responses in men (OR = 2.71, 95% CI: 1.43-5.15). Eating at night was associated with stress responses in the univariate analysis (men: OR = 2.10, 95% CI: 1.16-3.80; women: OR = 1.61, 95% CI: 1.09-2.39). CONCLUSION: This study showed that stress responses were related to lifestyle among women but not among men. Among women, stress responses were related to sleeping for shorter periods, whereas they were related to working long hours among men. In addition, stress responses were related to eating at night in the univariate analysis, although this relationship was not seen in the multivariate analysis, in either sex.