The circadian rhythm plays a fundamental role in regulating biological functions, including sleep–wake preference, body temperature, hormonal secretion, food intake, and cognitive and physical performance. Alterations in circadian rhythm can lead to chronic disease and impaired sleep. The circadian rhythmicity in human beings is represented by a complex phenotype. Indeed, over a 24-h period, a person’s preferred time to be more active or to sleep can be expressed in the concept of morningness–eveningness. Three chronotypes are distinguished: Morning, Neither, and Evening-types. Interindividual differences in chronotypes need to be considered to reduce the negative effects of circadian disruptions on health. In the present review, we examine the bi-directional influences of the rest–activity circadian rhythm and sleep–wake cycle in chronic pathologies and disorders. We analyze the concept and the main characteristics of the three chronotypes.

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Binge eating patients present lower physical activity levels, which could be associated with lower exercise capacity. Specific physical activity can ensure broad beneficial results relating to eating disorders, depression, and body mass index (BMI) in bulimia; however, research on binge eating disorder (BED) is scarce. Our study aimed to investigate the effects of specific training as an addition to conventional treatment of eating disorder symptoms, anthropometric characteristics, and physical performance. Nineteen women with BED were included in a dietary and cognitive-behavioral therapy program. After medical examination, 10 women carried out Combined Aerobic and Anaerobic Exercise Training in addition to conventional treatment (CAAET group), whereas the remaining 9 followed the conventional treatment alone (CTRL group). All of the measurements were assessed before and after six months of treatment. In both groups, we observed a significant decrease in binge episodes, weight, and body mass index, and an increase in exercise capacity. Moreover, the CAAET group presented a greater improvement in aerobic performance than that observed in the CTRL group. Our results suggest that both interventions similarly improved BED symptoms. The addition of physical activity could be important in the long-term maintenance of both weight loss and reduction in binge episodes in BED patients.

Circadian rhythms influence daily behavior, psychological and physiological functions, as well as physical performance. Three chronotypes are distinguished according to the preferences people typically display for activity at certain times of day: Morning, Neither, and Evening types (M-, N-and E-types). The chronotype changes with age: eveningness tends to be stronger in youth and morningness in older age. The progressive shift toward eveningness during adolescence creates misalignment with morning society schedules and can lead to a deterioration in intellectual and physical performance. Soccer is one of the world's most popular sports practiced by adolescents and soccer workouts are usually held after school in the afternoon or evening. Performance in soccer is related to a host of factors, including physiological variables and motor skills that have a circadian variation. The aim of this study was to determine the effect of chronotype on motor skills specific to soccer, specifically whether agility, aerobic endurance, and explosive power differ among the three chronotypes in relation to the time of day. For this study 141 adolescent soccer players filled in the Morningness-Eveningness Questionnaire (MEQ) for the assessment of chronotype. A subsample of 75 subjects, subdivided in M-types (n= 25), E-types (n= 25), and N-types (n= 25), performed three tests (Sargent Jump Test -SJT, Illinois Agility Test -IAT, and 6-Minutes Run Test -6MRT) at a morning and an evening training session (9:00 am and 6:00 pm). Mixed ANOVA was used to test the interactions between chronotypes, physical performance, and time. On all tests, better performance during the morning than the evening session was observed for the M-types (p< .05), whereas the E-types performed better in the evening than in the morning session (p< .05), and no differences in test performance were detected for the N-types. These findings underline the importance of a correct chronobiological approach to sports training. Scheduling training sessions according to an athlete's circadian preferences could be a valid strategy to enhance performance.

SUMMARYUnconjugated hyperbilirubinaemia is a common finding in newborns. When it is exaggerated, it is usually investigated in order to exclude several diseases, such as newborn's haemolytic diseases, infections or hypothyroidism. Breast milk jaundice is a form of neonatal jaundice related to breast feeding and it is not usually associated with any clinical issue and/or other laboratory abnormalities. We describe a case of breast milk jaundice being associated, unexpectedly, to significant elevation of plasmatic liver and biliary enzymes. Despite the infant's good clinical condition and growth, several investigations were performed and these ruled out metabolic, infectious and autoimmune liver diseases. All liver function tests normalised by 6-7 months of life. We suggest that the finding of hypertransaminasaemia and hyper-γ-glutamyl transpeptidase in a benign clinical context (similar to what we described) should be followed for 6-7 months before performing sophisticated and expensive diagnostic investigations which aim at excluding some unlikely and severe diseases in a completely asymptomatic infant. BACKGROUND

The effect of sleep–wake rhythm disruption on neuromuscular control and muscle fatigue has received little attention. Because nurse shift work is so varied, including overnight duty, rotating shift schedules, early awakening, and interrupted nocturnal sleep, it offers an interesting model to study this paradigm. It has been investigated so far using only subjective markers. A combined approach based on the simultaneous analysis of surface electromyographic (sEMG) and force signals can objectively detect possible deficits in neuromuscular control and muscle fatigue. With this study we investigated neuromuscular activation and muscle contraction capacity at submaximum and maximum level in nurses working two night-shift schedules and compared them to levels in nurses working entirely in day shifts. Sleep quality and activity levels were also assessed. The study sample was 71 nurses grouped by their shift work schedule: night shift for 5 days (NS 5 , n = 46), night shift for 10 days (NS 10 , n = 9), and only day/swing shift (DS, n = 16). Before and after the shift-work cycle, maximum voluntary contraction (MVC) force and muscle activation, neuromuscular control, and muscle fatigability were measured in the finger flexor muscles. Activity level and sleep quality during the shift-work cycle were recorded with a wrist actigraph. After the shift-work cycles, MVC force and muscle activation were decreased (−11 ± 3% and −33 ± 3%, p < 0.001) as was neuromuscular control (−36 ± 8%, p = 0.007), whereas muscle fatigability was increased (+ 19 ± 9%, p = 0.006) in the NS 5 and the NS 10 group. Sleep quality was lower in the NS 5 and the NS 10 group (−8 ± 1.8% and −15%3, respectively, p < 0.001), while the activity level for the three groups was similar. There was a clear reduction in neuromuscular control and an increase in muscle fatigue in the nurses working the night shift. These findings may inform of work schedule planning or recommendations for devising new recovery strategies to counteract neuromuscular alterations in night shift nurses.

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