The association between anxiety, hunger, the enjoyment of eating foods and the satiety after food intake in individuals working a night shift compared with after taking a nocturnal sleep: A prospective and observational study.

Subjective responses to meals are altered by shortened sleep time and anxiety state, but this effect has been poorly studied in shift workers - who act as a typical model concerning sleep restriction and present high levels of anxiety. The objective of this study was to compare subjective perceptions of meals and the levels of anxiety in the same subjects after working night shifts and after taking a nocturnal sleep, and to investigate associations between the responses to meals and the levels of anxiety under these two conditions. The study evaluated 34 male permanent night-shift workers who worked a 12-h shift followed by a 36-h rest period. Evaluations included: sleep pattern (on three days after working night shifts and after sleeping at night); hunger, enjoyment of eating foods and satiety after a meal (evaluated by visual analogue scales on three non-consecutive days after working night shifts and after nocturnal sleeps); and state of anxiety (on a day after working a night shift and a day after a nocturnal sleep). In the days following a night shift, workers had higher mean hunger scores before lunch and higher anxiety scores than when they had slept at night (p = 0.007 and 0.001, respectively). Linear regression indicated that, after a night shift, anxiety scores were negatively associated with hunger before breakfast (p = 0.04) and lunch (p = 0.03), the enjoyment of eating foods (p = 0.03) and the number of meals eaten during the course of the 24 h (p = 0.03). It is concluded that night shifts increase mean hunger and anxiety scores. Anxiety levels seem to interfere with the responses associated with food consumption.

Association between chronotype, food intake and physical activity in medical residents.

An individual's chronotype is a trait which reflects his/her diurnal preferences for the times of rest and activities, and displays a continuum from morningness to eveningness. Studies have shown that eveningness tends to be associated with a less healthy lifestyle, including increased likelihood of developing obesity. In this study, we examined the relationship between chronotype and food intake, physical sleep and activity in 72 resident physicians (52 women and 20 men). Assessments included chronotype evaluation by the Horne and Ostberg Morningness-Eveningness questionnaire (MEQ); food intake pattern through a self-administered food diary that was kept over the course of 3 non-successive days; physical activity level, using the Baecke questionnaire (BQ); sleep quality and quantity using the Pittsburgh Sleep Quality Index (PSQI); and sleepiness, Epworth Sleepiness Scale (ESS). Linear regression analyses, after adjustments for age, sex, body mass index (BMI), hours of additional work per week ESS and total physical activity score, showed that the chronotype score was negatively associated with cholesterol (coefficient = -0.24; p = 0.04), sweets (coefficient = -0.27, p = 0.03) and vegetables (coefficient = -0.26; p = 0.04) intakes. Following the same statistical adjustments, the chronotype score was positivity associated with leisure-time index (coefficient = 0.26, p = 0.03) and BQ total score (coefficient = 0.27, p = 0.03). We concluded that most issues related to nutrition problems and unhealthy lifestyle were associated with scores indicative of eveningness. These findings emphasize the importance of assessing an individual's chronotype when examining feeding behavior.

Chronotype, social jetlag and sleep debt are associated with dietary intake among Brazilian undergraduate students.

Undergraduate students experience a form of circadian misalignment - known as "social jetlag" - that represents the discrepancy in timing between their circadian and social clocks. Whilst social jetlag is not dependent upon chronotype, the two phenomena tend to be related; evening types show a tendency to have a greater social jetlag, for example. Moreover, evening types have been found to be more likely to have inadequate eating habits than do morning types. The objective of this study was to examine the relationship between chronotype, social jetlag, perceived sleep debt and dietary intake in Brazilian undergraduate students. The chronotype was derived from mid-sleep time on free days (MSF) at the weekend. Social jetlag was calculated as the absolute difference between mid-sleep time on weekdays and weekends. Perceived sleep debt was calculated using the difference between students' preferred weekday sleep duration and their self-reported actual weekday sleep duration. Correlations were found between chronotype and breakfast time (r = 0.24, p = 0.003) and lunch time (r = 0.19, p = 0.01). Multiple regression analyses showed that chronotype was positively associated with consumption of meat (ß = 0.21; p = 0.003); social jetlag was negatively associated with consumption of beans (ß = -0.16; p = 0.02) and perceived sleep debt was positively associated with consumption of beverages (ß = 0.15; p = 0.02) and dairy products (ß = 0.17; p = 0.01) and negatively associated with consumption of cereals and pasta (ß = -0.16; p = 0.02). It is concluded that, in undergraduate students, chronotype (MSF), social jetlag and perceived sleep debt can influence the type and amount of some food groups consumed at mealtimes.

Nutritional status and eating habits of bus drivers during the day and night.

The aim of this study was to compare anthropometry and food intake patterns in bus drivers working during the day and night. One hundred and fifty males (81 night workers and 69 day workers) participated in the study. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. Measurements of height, weight, waist circumference (WC), systolic and diastolic blood pressure, blood glucose, and lipid profile were obtained. A significant difference between groups was observed for mean WC (98.5 ± 10.7 cm in day workers versus 103.2 ± 9.7 cm in night workers; p = 0.005). Night workers had higher prevalence of being overweight and obese (BMI ≥ 25 kg/m(2)) than day workers (78.2% day workers versus 90.2% night workers; p = 0.004) and increased WC (>94 cm) (72.4% day workers versus 86.4% night workers; p = 0.03). Significant differences were found for meat consumption (2.3 servings ±0.9 for night workers versus 2.0 servings ±0.7 day workers, p = 0.04) and fruit intake (0.9 servings ±0.4 for night workers versus 0.7 servings for day workers ±0.5; p = 0.006). Night workers had a lower intake of vegetables than recommended compared to day workers (100 versus 92.7%, respectively, p = 0.01) and higher intake of oil (40.7 versus 24.6%, p = 0.03). Multivariate logistic regression analysis indicated that night work was associated with being overweight (OR = 2.94, 95% IC: 1.14-7.66, p = 0.03) and abnormal values of WC (OR = 2.82, 95% IC: 1.20-6.69, p = 0.009) after adjusting for potential confounders. It is concluded that night workers had a higher prevalence and risk of being overweight/obese and increased WC compared with day workers. Night workers also presented a higher proportion of inappropriate intakes of food groups when compared to day workers, even though both groups were eating poor diets. These results demonstrate the need of lifestyle-intervention programs in these workers.

Sleep pattern is associated with adipokine levels and nutritional markers in resident physicians.

Shift work and long hours of work are common in medical training and have been associated with a higher propensity for developing nutritional problems and obesity. Changes in leptin and ghrelin concentrations - two hormones that contribute importantly to the central regulation of food intake - are poorly described in this population. The aim of this study was to identify possible negative associations between sleep patterns, nutritional status and serum levels of adipokines. The study included 72 resident physicians (52 women and 20 men) who underwent the following assessments: nutritional assessment (3-day dietary recall evaluated by the Adapted Healthy Eating Index), anthropometric variables, fasting metabolism, physical activity level, sleep quality and sleepiness. Resident physicians with poor sleep quality reported greater weight gain after the beginning of residency (5.1 and 3.0 kg, respectively; p = 0.01) and higher frequency of abnormal waist circumference (44.2 and 17.6%, respectively; p = 0.04) than those with better sleep quality. Mean ghrelin concentration was greater in volunteers with poor sleep quality (64.6 ± 67.8 and 26.2 ± 25.0 pg/mL, respectively; p = 0.04). Women identified as having excessive daytime sleepiness had lower levels of leptin (9.57 ± 10.4 ng/mL versus 16.49 ± 11.4 ng/mL, respectively; p = 0.03) than those without excessive sleepiness. Furthermore, correlations were found between hours of additional work per week and: intake of cereals, bread and pasta (r = 0.22, p = 0.01); intake of servings of fruits (r = -0.20; p = 0.02) and beans (r = -0.21; p = 0.01); and global score for Adapted Healthy Eating Index (r = -0.23; p = 0.008; Table 3). The sleep quality total score correlated with servings of beans (r = -0.22; p = 0.01) and servings of oils (r = 0.23; p = 0.008). Significant correlations were found between mean of time of sleep and servings of cereals, bread and pasta (r = 0.20; p = 0.02), servings of meat (r = -0.29; p = 0.02) and cholesterol levels (r = 0.27; p = 0.03). These observations indicate that sleep patterns and long working hours of resident physicians are negatively associated with biological markers related to central food control, the lipid profile, cholesterol levels and eating healthy foods. These factors may predispose these shift workers to become overweight and develop metabolic disorders.

Wrist actimetry circadian rhythm as a robust predictor of colorectal cancer patients survival.

The disruption of the circadian timing system (CTS), which rhythmically controls cellular metabolism and proliferation, accelerated experimental cancer progression. A measure of CTS function in cancer patients could thus provide novel prediction information for outcomes, and help to identify novel specific therapies. The rest-activity circadian rhythm is a reliable and non-invasive CTS biomarker, which was monitored using a wrist watch accelerometer for 2 days in 436 patients with metastatic colorectal cancer. The relative percentage of activity in-bed versus out-of-bed (I < O) constituted the tested CTS measure, whose prognostic value for overall survival (OS) and progression-free survival (PFS) was determined in a pooled analysis of three patient cohorts with different treatment exposures. Median OS was 21.6 months [17.8-25.5] for patients with I < O above the median value of 97.5% as compared to 11.9 months [10.4-13.3] for those with a lower I < O (Log-rank p < 0.001). Multivariate analyses retained continuous I < O as a joint predictor of both OS and PFS, with respective hazard ratios (HR) of 0.954 (p < 0.001) and 0.970 (p < 0.001) for each 1% increase in I < O. HRs had similar values in all the patient subgroups tested. The circadian physiology biomarker I < O constitutes a robust and independent quantitative predictor of cancer patient outcomes, that can be easily and cost-effectively measured during daily living. Interventional studies involving 24-h schedules of clock-targeted drugs, light intensity, exercise and/or meals are needed for testing the relevance of circadian synchronization for the survival of patients with disrupted rhythms.

Daily rhythms of the sleep-wake cycle.

The amount and timing of sleep and sleep architecture (sleep stages) are determined by several factors, important among which are the environment, circadian rhythms and time awake. Separating the roles played by these factors requires specific protocols, including the constant routine and altered sleep-wake schedules. Results from such protocols have led to the discovery of the factors that determine the amounts and distribution of slow wave and rapid eye movement sleep as well as to the development of models to determine the amount and timing of sleep. One successful model postulates two processes. The first is process S, which is due to sleep pressure (and increases with time awake) and is attributed to a 'sleep homeostat'. Process S reverses during slow wave sleep (when it is called process S'). The second is process C, which shows a daily rhythm that is parallel to the rhythm of core temperature. Processes S and C combine approximately additively to determine the times of sleep onset and waking. The model has proved useful in describing normal sleep in adults. Current work aims to identify the detailed nature of processes S and C. The model can also be applied to circumstances when the sleep-wake cycle is different from the norm in some way. These circumstances include: those who are poor sleepers or short sleepers; the role an individual's chronotype (a measure of how the timing of the individual's preferred sleep-wake cycle compares with the average for a population); and changes in the sleep-wake cycle with age, particularly in adolescence and aging, since individuals tend to prefer to go to sleep later during adolescence and earlier in old age. In all circumstances, the evidence that sleep times and architecture are altered and the possible causes of these changes (including altered S, S' and C processes) are examined.

Adipokine levels are altered by shiftwork: a preliminary study.

Shiftwork is often associated with metabolic diseases, and in the past few years, several cytokines have been postulated to contribute to various diseases, including insulin resistance. The aim of this study was to compare the concentrations of adiponectin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in samples of young adult men exposed to a fixed (i) night shift (n = 9), working from 22:00 to 06:00 h; (ii) early morning shift (n = 6), working from 06:00 to 14:00 h; and (iii) day shift (n = 7), working from 08:00 to 17:00 h. The fixed night-shift and early-morning-shift samples were considered collectively as a shiftworker group given their work times. Blood samples were collected during the regular working day at 4-h intervals over the course of 24 h, thus totaling six samples. Morphological and physical activity parameters did not differ between the three groups. Total energy intake was lowest on the early morning shifts (p < .03). Both shiftworker groups ingested a significantly higher percentage of fat (p < .003) and a lower percentage of carbohydrate (p < .0005) than the day group. The early morning group had a lower mean 24-h level of adiponectin than the other two groups (p = .016), and both the early morning and night groups exhibited higher mean 24-h levels of TNF-α than the day group (p = .0001). The 24-h mean levels of IL-6 did not differ significantly between the groups (p = .147). None of the groups exhibited a significant circadian effect on adiponectin (p = .829), TNF-α (p = .779), or IL-6 (p = .979) levels. These results indicate that individuals who are enrolled in shiftwork are susceptible to alterations in the secretion of cytokines that are involved in insulin resistance and cardiovascular disease, both of which are known to affect this population.

Prediction of overall survival through circadian rest-activity monitoring during chemotherapy for metastatic colorectal cancer.

The clinical relevance of circadian rhythm modifications in patients on chemotherapy is unknown. Even so, circadian parameter I

Hormonal appetite control is altered by shift work: a preliminary study.

Shift work has been associated with a higher propensity for developing nutritional problems and obesity. However, the possible changes in leptin and ghrelin (2 hormones that contribute importantly to the central regulation of food intake) concentrations in this population are poorly described. The objective of the study was to evaluate the daily concentrations of leptin, nonacylated ghrelin, and acylated ghrelin and the appetite ratings in men working different shift schedules. Daily concentrations of nonacylated ghrelin, acylated ghrelin, and leptin and appetite were measured in 3 groups of subjects: workers on fixed night shifts (n = 9), fixed early morning shifts (n = 6), and fixed day shifts (n = 7). Appetite was evaluated by a validated questionnaire. Blood samples were collected every 4 hours over the course of 24 hours for a total of 6 samples. When comparing the 3 groups, leptin concentrations at 8:00 am and 4:00 pm for those workers on the day shift were significantly lower than for those on the early morning shift; and concentrations at noon for those workers on the day shift were significantly lower than for those on the night shift. Nonacylated and acylated ghrelin concentrations were significantly lower for those workers on the early morning shift than for those on the day shift. In general, appetite was the lowest in those working the early morning shift. Shift workers on the early morning shift have lower appetites and concentrations of leptin and nonacylated and acylated ghrelin than the workers on other shifts. Further studies are required to better understand the detailed needs of these individuals.

The circadian body temperature rhythm of Djungarian Hamsters (Phodopus sungorus) revealing different circadian phenotypes.

Djungarian hamsters (Phodopus sungorus) of our breeding stock show three rhythmic phenotypes: wild type (WT) animals which start their activity shortly after "lights-off" and are active until "lights-on"; delayed activity onset (DAO) hamsters whose activity onset is delayed after "lights-off" but activity offset coincides with "lights-on"; and arrhythmic hamsters (AR) that are episodically active throughout the 24-h day. The main aim of the present study was to investigate whether the observed phenotypic differences are caused by an altered output from the suprachiasmatic nuclei (SCN). As a marker of the circadian clock, the body temperature rhythm purified from masking effects due to motor activity was used. Hamsters were kept singly under standardized laboratory conditions (L:D=14:10h, T: 22°C±2°C, food and water ad libitum). Body temperature and motor activity were monitored by means of implanted G2-E-Mitters and the VitalView(®) System (MiniMitter). Each phenotype showed distinctive rhythms of overt activity and body temperature, these two rhythms being very similar for each phenotype. Correcting body temperatures for the effects of activity produced purified temperature rhythms which retained profiles that were distinctive for the phenotype. These results show that the body temperature rhythm is not simply a consequence of the activity pattern but is caused by the endogenous circadian system. The purification method also allowed estimation of thermoregulatory efficiency using the gradients as a measure for the sensitivity of body temperature to activity changes. In WT and DAO hamsters, the gradients were low during activity period and showed two peaks. The first one occurred after "lights-on", the second one preceded the activity onset. In AR hamsters, the gradients did not reveal circadian changes. The results provide good evidence that the different phenotypes result from differences in the circadian clock. In AR hamsters, the SCN do not produce an obvious circadian signal. With regard to DAO hamsters, it remains to be investigated whether the clockwork itself or the afferent entraining pathways are abnormal in comparison with the WT hamsters.

Respiratory rhythms in stingless bee workers: circadian and ultradian components throughout adult development.

The workers of the stingless bee, Melipona quadrifasciata, assume different tasks during their adult life. Newly emerged individuals remain inside the nest, without contact with the external environment. Maturing workers go to more peripheral regions and only the oldest, the foragers, leave the nest. As this diversity of activities implies different metabolic patterns, oxygen consumption has been measured in workers of three different ages: 24-48 h (nurses), 10-15 days (builders), and older than 25 days (foragers). Oxygen consumption of individually isolated workers was determined by intermittent respirometry, under constant darkness and temperature of 25±1 °C. Sets of 24-h measurements were obtained from individuals belonging to each of the three worker groups. Rhythmicity has been assessed in the daily (24 h) and ultradian (5-14 h) domains. This experimental design allowed detection of endogenous rhythms without the influence of the social group and without inflicting stress on the individuals, as would be caused by their longer isolation from the colony. Significant 24-h rhythms in oxygen consumption were present in nurses, builders and foragers; therefore, workers are rhythmic from the age of 24-48 h. However, the amplitude of the circadian rhythm changed according to age: nurses showed the lowest values, while foragers consistently presented the largest ones, about ten times larger than the amplitude of nurses' respiratory rhythm. Ultradian frequencies were detected for all worker groups, the power and frequencies of which varied little with age. This means that the ultradian strength was relatively larger in nurses and apparently maintains some relationship with the queen's oviposition episodes.

Circadian rhythms and cognition.

Like all circadian (near-24-h) rhythms, those of cognition have endogenous and exogenous components. The origins of these components, together with effects of time awake upon cognitive performance, are described in subjects living conventionally (sleeping at night and active during the daytime). Based on these considerations, predictions can be made about changes that might be expected in the days after a time-zone transition and during night work. The relevant literature on these circumstances is then reviewed. The last section of the chapter deals with sleep-wake schedules where both regular and irregular sleeps are taken (anchor sleep).

Effects of Ramadan on physical performance: chronobiological considerations.

This article focuses on changes in Ramadan during the course of the waking day in physical performance, mental performance and gastrointestinal function. Possible explanations of the changes are considered by reference to the roles of the body clock and external factors such as the environment and the individual's lifestyle. The effects of these factors upon training schedules and upon changing the times of training are then discussed in terms of physiology and biochemistry. Delaying the time of training until after sunset has advantages and disadvantages, but it is a regimen that is unlikely to be widely accepted in non-Muslim countries. It is clear that the detailed nature of the problems involved and dealing with them in a manner based upon a firm body of knowledge requires far more experimental investigation.

Sports performance: is there evidence that the body clock plays a role?

Athletic performance shows a time-of-day effect, possible causes for which are environmental factors (which can be removed in laboratory studies), the sleep-wake cycle and the internal "body clock". The evidence currently available does not enable the roles of these last two factors to be separated. Even so, results indicate that the body clock probably does play some role in generating rhythms in sports performance, and that to deny this is unduly critical. Protocols to assess the separate roles of the body clock and time awake are then outlined. A serious impediment to experimental work is muscle fatigue, when maximal or sustained muscle exertion is required. Dealing with this problem can involve unacceptably prolonged protocols but alternatives which stress dexterity and eye-hand co-ordination exist, and these are directly relevant to many sports (shooting, for example). The review concludes with suggestions regarding the future value to sports physiology of chronobiological studies.

Circadian rhythm in rest and activity: a biological correlate of quality of life and a predictor of survival in patients with metastatic colorectal cancer.

The rest-activity circadian rhythm (CircAct) reflects the function of the circadian timing system. In a prior single-institution study, the extent of CircAct perturbation independently predicted for survival and tumor response in 192 patients receiving chemotherapy for metastatic colorectal cancer. Moreover, the main CircAct parameters correlated with several health-related quality of life (HRQoL) scales. In this prospective study, we attempted to extend these results to an independent cohort of chemotherapy-naive metastatic colorectal cancer patients participating in an international randomized phase III trial (European Organisation for Research and Treatment of Cancer 05963). Patients were randomized to receive chronomodulated or conventional infusion of 5-fluorouracil, leucovorin, and oxaliplatin as first-line treatment for metastatic colorectal cancer. Patients from nine institutions completed the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-C30 and wore a wrist accelerometer (actigraph) for 3 days before chemotherapy delivery. Two validated parameters (I |0.25|; P < 0.01). I

Effects of one night of partial sleep deprivation upon diurnal rhythms of accuracy and consistency in throwing darts.

Sixty subjects were tested five times per waking day on two occasions for accuracy and reliability in throwing 20 darts at a target. Two experimental conditions were investigated: following a normal nocturnal sleep (7-8 h sleep, normal) and after having retired to bed 4 h later than normal the previous night but rising at the normal time (3-4 h sleep, sleep deprivation). Sublingual (core) temperature and subjective estimates of alertness and fatigue were measured in all sessions. Performance at throwing darts was assessed by three methods: mean distance of the dart from the bulls-eye; number of times the target was missed; and variability of the scores from the darts thrown. There was no evidence that performance was affected by physical fatigue arising during the course of throwing the 20 darts. All variables showed significant diurnal rhythms, those of alertness and performance being phased over 1 h earlier than core temperature, and that of fatigue over 1 h earlier than the inverse of temperature. Core temperature was not affected by sleep deprivation, but all other variables showed significant changes, indicative of mood and performance decrement. Increasing time awake was associated with decreased alertness and increased fatigue, as well as slight negative effects upon performance. We conclude that the simple task of throwing darts at a target provides information about chronobiological changes in circumstances where time awake and sleep loss might affect psychomotor performance.

Some chronobiological and physiological problems associated with long-distance journeys.

Long-distance travel is becoming increasingly common. Whatever the means of transport, any long journey will be associated with "travel fatigue". The symptoms associated with this phenomenon result from a changed routine (particularly sleep lost and meals) and the general disruption caused by travel. Planning any trip well in advance will minimise many of these problems, but some factors are less easy to guard against. These problems include sitting in cramped and uncomfortable conditions and, with flights, the hypoxic environment in the cabin. After arrival at the destination in another country, there can be problems coping with the local language, alterations in food and different customs. If the flight has crossed the equator, then there is likely to be a change in season and natural lighting and, if it has crossed several time zones, there will also be the problem of "jet lag", caused by a transient desynchrony between the "body clock" and the new local time. Moreover, the new environment might differ from the place of departure with regard to ambient temperature and humidity, altitude, natural lighting (including ultraviolet radiation) and pollution. The traveller needs to be aware of these changes before setting off, so that appropriate preparations (clothing, for example) can be made.

Circadian disruption, fatigue, and anorexia clustering in advanced cancer patients: implications for innovative therapeutic approaches.

A disruption of the circadian timing system, as identified by monitoring of marker biorhythms, is common in cancer patients. The recording of the rest-activity rhythm with a wrist actigraph has been commonly used. This noninvasive monitoring allows a robust estimation of circadian disruption. The authors have previously found that altered patterns of circadian rest-activity rhythms are significantly and independently associated with the severity of fatigue and anorexia in patients with metastatic colorectal cancer. Elevated proinflammatory cytokines could partly account for this circadian disruption and its associated constitutional symptoms. Here, the authors present and discuss the data supporting the hypothesis that circadian disruption is often associated with fatigue and anorexia, which in turn further alter and dampen circadian synchronization, thus, creating a vicious cycle. This body of evidence paves the path for innovative therapeutic approaches targeting the circadian timing system in an effort to diminish constitutional symptoms induced by cancer and some anticancer treatments.