The bright-nights and dim-days of the urban photoperiod: implications for circadian rhythmicity, metabolism and obesity

Glucose Challenge Uncovers Temporal Fungibility of Metabolic Homeostasis over a day:night cycle

Rhythmicity is a cornerstone of behavioral and biological processes, especially metabolism, yet the mechanisms behind metabolite cycling remain elusive. This study uncovers a robust oscillation in key metabolite pathways downstream of glucose in humans. A purpose-built 13C6-glucose isotope tracing platform was used to sample Drosophila every 4h and probe these pathways, revealing a striking peak in biosynthesis shortly after lights-on in wild-type flies. A hyperactive mutant (fumin) demonstrates increased Krebs cycle labelling and dawn-specific glycolysis labelling. Surprisingly, neither underlying feeding rhythms nor the presence of food availability explain the rhythmicity of glucose processing across genotypes, suggesting a robust internal mechanism for metabolic control of glucose processing. These results align with clinical data highlighting detrimental effects of mistimed energy intake. Our approach offers a unique insight into the dynamic range of daily metabolic processing and provides a mechanistic foundation for exploring circadian metabolic homeostasis in disease contexts.

Does the Dysregulation of Social Rhythms Syndrome (DYMERS) be Considered an Essential Component of Panic Disorders?

This editorial explores the role of hyperactivity and social rhythm dysregulation in bipolar disorder (BD) and related syndromes. Social Rhythm Dysregulation Syndrome (DYMERS) is proposed as a common vulnerability across various disorders, including panic disorder (PD), attention deficit hyperactivity disorder, and post-traumatic stress disorder. A study conducted on a sample of elderly individuals participating in an active aging study investigated whether individuals with PD exhibit higher biological rhythm dysregulation compared to those without PD. The sample, consisting of 119 individuals, revealed that those with a lifetime PD diagnosis scored significantly higher on the dysregulation of biological rhythms scale compared to those without panic disorder. A higher prevalence of depressive episodes was found in individuals with PD at the time of the interview. Notably, a small sample of elderly individuals with panic disorder, voluntarily selected for a physical exercise trial, showed a significantly higher level of dysregulation of social rhythms compared to those without panic disorder. This study opens a debate on the accuracy of paper and pencil screening tests for bipolar disorders, especially regarding false positives in individuals with panic disorder. Our hypothesis is that DYMERS could be a shared vulnerability substrate for various disorders, serving as a basis for bipolar onset in the presence of a hyperactivity profile, even with genetic features. The data collected from older adults suggest that social rhythm dysregulation is a typical feature of PD, regardless of the coexistence of a depressive episode. While the study has limitations due to a small sample size, the findings warrant careful analysis and suggest the need for larger-scale replication studies. If confirmed, the dysregulation of rhythms and its association with depressive disorders highlight a significant area of vulnerability for serious psychopathological disorders, emphasizing the importance of extending research to younger populations.

Dysregulation of mood, energy, and social rhythms syndrome (DYMERS): A working hypothesis

A syndrome centered on the dysregulation of behavioral rhythms (DBR) is discussed. Recent pandemic brought to observe: (1) Having a DBR affecting sleep patterns, eating habits, and social interactions, before the lockdown period, was a determinant for depressive episodes during the lockdown; (2) In tighter lockdowns, DBR triggered depressive episodes in bipolar patients; (3) DBR in healthcare workers under pressure was a determinant of burnout; (4) DBR influenced the course of chronic diseases by altering immune responses. In addition, it was found that scoring positive on the Mood Disorder Questionnaire (MDQ) was closely associated with the dysregulation of sleep rhythms. MDQ is a screening tool for bipolar disorder (BD), criticized for detecting too many false positives. Studies showed that positivity to the MDQ implied a severe impairment of quality of life even in people without psychiatric diagnoses. According to this evidence, three different hyperactivation levels could be proposed (from normality to pathology): firstly, an adaptive increase in energy (e.g. athletes performing well); secondly, a DBR determined from the continuous stimulation of stress hormones, with possible positive scores on the MDQ without a diagnosis of bipolar disorder, like in burnout syndromes and, thirdly, hyperactivity during manic episodes. The Dysregulation of Mood, Energy, and Social Rhythms Syndrome (DYMERS), the second level of the scale, is proposed as a working hypothesis. DYMERS is also seen as a vulnerable condition that may evolve in other disorders (including BD) according to the individual susceptibility (including genetic predisposition) and the specific nature/level of the stressor.

Does the Response to a Stressful Condition in Older Adults with Life Rhythm Dysregulations Provide Evidence of the Existence of the "Dysregulation of Mood, Energy, and Social Rhythms Syndrome"?

OBJECTIVE

The COVID-19 lockdown periods have given rise to the "Dysregulation of Mood, Energy, and Social Rhythms Syndrome" (DYMERS). This syndrome is characterized by a poor regulation of biological, social, and behavioral rhythms, including sleep, nutrition, and social contacts. The purpose of this cohort study was to examine whether older adults with pre-existing DYMERS had a more negative perception of their health-related quality of life (H-QoL) during the COVID-19 pandemic lockdown, regardless of the presence of concurrent mood disorders.

METHOD

The entire study population (N = 93; age > 65 year) was categorized based on whether they exhibited dysregulated rhythms at the outset of the study. A comparison was made between DYMERS-positive individuals and DYMERS-negative individuals, and we assessed their H-QoL at the conclusion of the study. We also compared the H-QoL of individuals in the cohort who did not have a positive depression score to understand the impact of the rhythm dysregulation alone.

RESULTS

The frequency of individuals with a critical health-related quality of life score (SF12 < 25) was higher in the cohort with pre-existing DYMERS during lockdown (33.33% vs. 6.17%). This difference remained significant even when only individuals without depressive symptomatology were considered (27.27% vs. 2.60%).

CONCLUSION

The results of this study indicate that DYMERS can exert a substantial influence on health-related quality of life (H-QoL), even when mood disturbances are not present. Additional research is required to investigate the relationship between DYMERS and other psychiatric conditions as well as its nature as a standalone disorder.

Ubiquitous light-emitting diodes: Potential threats to retinal circadian rhythms and refractive development

The use of light-emitting diodes (LEDs) has increased considerably in the 21st century with humans living in a modern photoperiod with brighter nights and dimmer days. Prolonged exposure to LEDs, especially at night, is considered a new source of pollution because it may affect the synthesis and secretion of retinal melatonin and dopamine, resulting in negative impacts on retinal circadian clocks and potentially disrupting retinal circadian rhythms. The control of ocular refraction is believed to be related to retinal circadian rhythms. Moreover, the global prevalence of myopia has increased at an alarming rate in recent decades. The widespread use of LEDs and the rapid increase in the prevalence of myopia overlap, which is unlikely to be a coincidence. The connection among LEDs, retinal circadian rhythms, and refractive development is both fascinating and confusing. In this review, we aim to develop a systematic framework that includes LEDs, retinal circadian rhythms and refractive development. This paper summarizes the possible mechanisms by which LEDs may disrupt retinal circadian rhythms. We propose that prolonged exposure to LEDs may induce myopia by disrupting retinal circadian rhythms. Finally, we suggest several possible countermeasures to prevent LED interference on retinal circadian rhythms, with the hope of reducing the onset and progression of myopia.

[Association between parents-children verbal communication time and the adiposity levels of chilean pre-schoolchildren]

OBJECTIVE

To determine the association between the time of verbal communication parents-children with the adiposity levels of pre-schoolchildren, and secondly to describe the socio-demographic, and body composition outcomes of pre-schoolchildren by the verbal communication parents-children time.

MATERIALES Y METHODS

A descriptive, cross-sectional study of multi-centric application, with participation of (n=70) pre-scholars. The outcomes described were the adiposity, socio-demographic data of parents and the time of verbal communication parents-children.

RESULTS

Considering a low (<100 min/day) versus a high (≥100 min/day) time of verbal communication parents-children, there were significant differences in the weight of the obesity classification "total communication/day" [TC] (TC<100 min/day 20.6±4 vs. TC≥100 min/day 18.4±3 kg, P=0.039), zweight/height (TC<100 min/day 1.791±8 vs. TC≥100 min/day 1.010±4, P=0.030), lean mass in kg (TC<100 min/day 7.5±3 vs. TC≥100 min/day 6.3±2 kg, P=0.046), body fat in % (TC<100 min/day 36.3±2 vs. TC≥100 min/day 33.9±3%, P<0.05). The height and ratio weight/height do not showed significant association with the time of verbal communication parents-children. Additionally, muscle mass (TC<100 min/day 5.7±3 vs. TC≥100 min/day 5.1±3 kg, P=0.047), and trunk lean mass (TC<100 min/day 5.2± 4 vs. 4.6±3 kg, P=0.039) were significantly associated with the main outcome.

CONCLUSIONS

The daily time of verbal communication parents-children is significantly associated with higher levels of adiposity by the weight, zweight/height, and body fat in pre-schoolchildren. These findings require major and more complex research for corroborating.

Is Bipolar Disorder the Consequence of a Genetic Weakness or Not Having Correctly Used a Potential Adaptive Condition?

It is hypothesized that factors associated with bipolar disorder could, uer defined conditions, produce adaptive behaviors. The aim is to verify whether a genetic feature associated with bipolar disorder can be found in people without bipolar disorder but with hyperactivity/exploration traits. Healthy old adults (N = 40) recruited for a previous study on exercise were subdivided using a previously validated tool into those with and without hyperactivity/exploration traits and compared with a group of old patients with bipolar disorder (N = 21). The genetic variant RS1006737 of CACNA1C was analyzed using blood samples, DNA extraction, real-time PCR, FRET probes, and SANGER method sequencing. People with hyperactivity/exploration traits and without bipolar disorder were like people with bipolar disorder regarding the frequency of the genetic variant (OR = 0.79, CI95%: 0.21-2.95), but were different from people without either hyperactivity/exploration traits and bipolar disorder (OR = 4.75, CI95%: 1.19-18.91). The combined group of people with hyperactivity/exploration traits without bipolar disorder plus people with bipolar disorder had a higher frequency of the variant than people without either hyperactivity/exploration traits or bipolar disorder (OR = 4.25, CI95%: 1.24-14.4). To consider the genetic profile of bipolar disorder not an aberrant condition opens the way to a new approach in which the adaptive potential would be a central point in psychosocial treatment in addition to drug therapy. Future research can confirm the results of our study.

Circadian rhythms-related disorders in diurnal fat sand rats under modern lifestyle conditions: A review

Modern lifestyle reduces environmental rhythmicity and may lead to circadian desynchrony. We are exposed to poor day-time lighting indoors and excessive night-time artificial light. We use air-conditioning to reduce ambient temperature cycle, and food is regularly available at all times. These disruptions of daily rhythms may lead to type 2 diabetes mellitus (T2DM), obesity, cardiometabolic diseases (CMD), depression and anxiety, all of which impose major public health and economic burden on societies. Therefore, we need appropriate animal models to gain a better understanding of their etiologic mechanisms, prevention, and management.We argue that the fat sand rat (Psammomys obesus), a diurnal animal model, is most suitable for studying the effects of modern-life conditions. Numerous attributes make it an excellent model to study human health disorders including T2DM, CMD, depression and anxiety. Here we review a comprehensive series of studies we and others conducted, utilizing the fat sand rat to study the underlying interactions between biological rhythms and health. Understanding these interactions will help deciphering the biological basis of these diseases, which often occur concurrently. We found that when kept in the laboratory (compared with natural and semi-wild outdoors conditions where they are diurnal), fat sand rats show low amplitude, nocturnal or arrhythmic activity patterns, dampened daily glucose rhythm, glucose intolerance, obesity and decreased survival rates. Short photoperiod acclimation exacerbates these pathologies and further dampens behavioral and molecular daily rhythms, resulting in CMD, T2DM, obesity, adipocyte dysfunction, cataracts, depression and anxiety. Increasing environmental rhythmicity by morning bright light exposure or by access to running wheels strengthens daily rhythms, and results in higher peak-to-trough difference in activity, better rhythmicity in clock genes expression, lower blood glucose and insulin levels, improved glucose tolerance, lower body and heart weight, and lower anxiety and depression. In summary, we have demonstrated that fat sand rats living under the correspondent of “human modern lifestyle” conditions exhibit dampened behavioral and biological rhythms and develop circadian desynchrony, which leads to what we have named “The Circadian Syndrome”. Environmental manipulations that increase rhythmicity result in improvement or prevention of these pathologies. Similar interventions in human subjects could have the same positive results and further research on this should be undertaken.

Relationship Between Circadian Strain, Light Exposure, and Body Mass Index in Rural and Urban Quilombola Communities

Industrialization has greatly changed human lifestyle; work and leisure activities have been moved indoors, and artificial light has been used to illuminate the night. As cyclic environmental cues such as light and feeding become weak and/or irregular, endogenous circadian systems are increasingly being disrupted. These disruptions are associated with metabolic dysfunction, possibly contributing to increased rates of overweight and obesity worldwide. Here, we aimed to investigate how activity-rest rhythms, patterns of light exposure, and levels of urbanization may be associated with body mass index (BMI) in a sample of rural and urban Quilombola communities in southern Brazil. These are characterized as remaining social groups who resisted the slavery regime that prevailed in Brazil. Quilombola communities were classified into five groups according to their stage of urbanization: from rural areas with no access to electricity to highly urbanized communities. We collected anthropometric data to calculate BMI, which was categorized as follows: from ≥ 18.5 kg/m² to < 25 kg/m² = normal weight; from ≥ 25 kg/m² to < 30 kg/m² = overweight; and ≥ 30 kg/m² = obese. Subjects were asked about their sleep routines and light exposure on workdays and work-free days using the Munich Chronotype Questionnaire (N = 244 included). In addition, we analyzed actimetry data from 121 participants with seven consecutive days of recordings. Living in more urbanized areas and higher intradaily variability (IV) of activity-rest rhythms were associated with an increased risk of belonging to the overweight or obese group, when controlling for age and sex. These findings are consistent with preclinical data and point to potential strategies in obesity prevention and promotion of healthy metabolic profiles.

Gender differences in blood pressure and body composition in schoolchildren ascendants from Amerindian and European

Background: In spite of there are a wide knowledge of the prevalence of hypertension in adult, there is poor information on schoolchildren of different ethnicity and gender.Aim: To compare the levels of blood pressure and other cardiometabolic risk factors for hypertension between schoolchildren of different gender and ethnicity.Material and methods: In a cross-sectional study, 540 schoolchildren (6-13 years) ascendants from a Chilean public school population were analysed by ethnicity and gender in four groups (Mapuches N = 55; European boys N = 199, and Mapuches N = 64, and European girls N = 222). The study included the measurement of cardiovascular (systolic and diastolic blood pressure) as main outcomes, as well as other cardiovascular (resting heart rate), body composition (body mass, BMI, waist circumference, fat mass, muscle mass), muscle strength (handgrip strength of dominant, non-dominant, and mean handgrip strength) as additional cardiometabolic outcomes.Results: The systolic blood pressure was significantly higher in Mapuches girls 126 ± 4 vs. their European counterparts 119 ± 3 mmHg, P < .002, as well as diastolic blood pressure, was higher in Mapuches girls 82 ± 5 vs. European girls 74 ± 3 mmHg, P < .0001. There were more 'prehypertensive' Mapuches girls 10 (15.6%) vs. European peers 22 (9.9%) at P < .0001, and the 'hypertension' was significantly more prevalent in Mapuches boys 19 (34.5%) vs. European peers 39 (19.4%) at P < .0001, as well as in Mapuches girls 16 (25%) vs. European peers 33 (14.9%) at P < .0001. The 'obesity' was less prevalent in Mapuches 10 (18.2%) vs. European boys 55 (27.4%) at P < .0001. The waist circumference was high in European 74 ± 4 vs. Mapuches 67 ± 6 cm, P < .012 in boys, although, waist circumference was high in Mapuches girls 75 ± 5 vs. European peers 71 ± 3 cm, P < .021. There were higher levels of muscle mass in Mapuches boys 19.5 ± 12 vs. European peers 17.1 ± 4 kg, P < .0001.Conclusion: Mapuches girls show higher levels of systolic and diastolic BP than European girls, Mapuches boys and girls are more hypertensive than European peers, but are less obese than European schoolchildren peers. These cardiometabolic differences that are more detrimental for endemic ethnic Latinoamerican groups are in need to be explored further.

Effects of Intermittent Fasting on the Circulating Levels and Circadian Rhythms of Hormones

Intermittent fasting has become an increasingly popular strategy in losing weight and associated reduction in obesity-related medical complications. Overwhelming studies support metabolic improvements from intermittent fasting in blood glucose levels, cardiac and brain function, and other health benefits, in addition to weight loss. However, concerns have also been raised on side effects including muscle loss, ketosis, and electrolyte imbalance. Of particular concern, the effect of intermittent fasting on hormonal circadian rhythms has received little attention. Given the known importance of circadian hormonal changes to normal physiology, potential detrimental effects by dysregulation of hormonal changes deserve careful discussions. In this review, we describe the changes in circadian rhythms of hormones caused by intermittent fasting. We covered major hormones commonly pathophysiologically involved in clinical endocrinology, including insulin, thyroid hormones, and glucocorticoids. Given that intermittent fasting could alter both the level and frequency of hormone secretion, decisions on practicing intermittent fasting should take more considerations on potential detrimental consequences versus beneficial effects pertaining to individual health conditions.

Chronotherapy

The objective of chronotherapy is to optimize medical treatments taking into account the body's circadian rhythms. Chronotherapy is referred to and practiced in two different ways: (1) to alter the sleep-wake rhythms of patients to improve the sequels of several pathologies; (2) to take into account the circadian rhythms of patients to improve therapeutics. Even minor dysfunction of the biological clock can greatly affect sleep/wake physiology causing excessive diurnal somnolence, increase in sleep onset latency, phase delays or advances in sleep onset, frequent night awakenings, reduced sleep efficiency, delayed and shortened rapid eye movement sleep, or increased periodic leg movements. Chronotherapy aims to restore the proper circadian pattern of the sleep-wake cycle, through adequate sleep hygiene, timed light exposure, and the use of chronobiotic medications, such as melatonin, that affect the output phase of circadian rhythms, thus controlling the clock. Concerning the second use of chronotherapy, therapeutic outcomes as diverse as the survival after open-heart surgery or the efficacy and tolerance to chemotherapy vary according to the time of day. However, humans are heterogeneous concerning the timing of their internal clocks. Not only different chronotypes exist but also the endogenous human circadian period (τ) is not a stable trait as it depends on many internal and external factors. If any scheduled therapeutic intervention is going to be optimized, a tool is needed for simple diagnostic and objectively measurement of an individual's internal time at any given time. Methodologic advances like the use of single-sample gene expression and metabolomics are discussed.

Light at Night and Risk of Pancreatic Cancer in the NIH-AARP Diet and Health Study

Circadian disruption may play a role in carcinogenesis. Recent research suggests that light at night (LAN), a circadian disruptor, may be a risk factor for cancer. Moreover, LAN has been linked to obesity and diabetes, two risk factors for pancreatic ductal adenocarcinoma (PDAC). Here we examine the relationship between LAN and PDAC in an epidemiologic study of 464,371 participants from the NIH-AARP Diet and Health Study. LAN was estimated from satellite imagery at baseline (1996), and incident primary PDAC cases were ascertained from state cancer registries. Cox proportional hazards models were used to estimate HRs and two-sided 95% confidence intervals (CI) for the association between quintiles of LAN and PDAC in the overall population stratified by sex. Over up to 16.2 years of follow-up, a total of 2,502 incident PDAC were identified in the cohort. Higher estimated LAN exposure was associated with an elevated PDAC risk. Compared with those living in areas in the lowest LAN quintile, those in areas in the highest quintile had a 27% increase PDAC risk [HR (95% CI), 1.24 (1.03-1.49)], with similar risk for men [1.21 (0.96-1.53)] and women [1.28 (0.94-1.75)]. In addition, stronger associations were observed in normal and overweight groups compared with the obese group (P interaction = 0.03). Our results support the hypothesis that LAN and circadian disruption may be risk factors for PDAC. SIGNIFICANCE: Our study suggests that higher LAN is a risk factor for pancreatic cancer, contributing to the growing literature that demonstrates the potentially adverse health effects of light pollution.

Circadian disruption, melatonin rhythm perturbations and their contributions to chaotic physiology

The aim of this report is to summarize the data documenting the vital nature of well-regulated cellular and organismal circadian rhythms, which are also reflected in a stable melatonin cycle, in supporting optimal health. Cellular fluctuations in physiology exist in most cells of multicellular organisms with their stability relying on the prevailing light:dark cycle, since it regulates, via specialized intrinsically-photoreceptive retinal ganglion cells (ipRGC) and the retinohypothalamic tract, the master circadian oscillator, i.e., the suprachiasmatic nuclei (SCN). The output message of the SCN, as determined by the light:dark cycle, is transferred to peripheral oscillators, so-called slave cellular oscillators, directly via the autonomic nervous system with its limited distribution. and indirectly via the pineal-derived circulating melatonin rhythm, which contacts every cell. Via its regulatory effects on the neuroendocrine system, particularly the hypothalamo-pituitary-adrenal axis, the SCN also has a major influence on the adrenal glucocorticoid rhythm which impacts neurological diseases and psychological behaviors. Moreover, the SCN regulates the circadian production and secretion of melatonin. When the central circadian oscillator is disturbed, such as by light at night, it passes misinformation to all organs in the body. When this occurs the physiology of cells becomes altered and normal cellular functions are compromised. This physiological upheaval is a precursor to pathologies. The deterioration of the SCN/pineal network is often a normal consequence of aging and its related diseases, but in today's societies where manufactured light is becoming progressively more common worldwide, the associated pathologies may also be occurring at an earlier age.

A large prospective investigation of outdoor light at night and obesity in the NIH-AARP Diet and Health Study

BACKGROUND

Research has suggested that artificial light at night (LAN) may disrupt circadian rhythms, sleep, and contribute to the development of obesity. However, almost all previous studies are cross-sectional, thus, there is a need for prospective investigations of the association between LAN and obesity risk. The goal of our current study was to examine the association between baseline LAN and the development of obesity over follow-up in a large cohort of American adults.

METHODS

The study included a sample of 239,781 men and women (aged 50-71) from the NIH-AARP Diet and Health Study who were not obese at baseline (1995-1996). We used multiple logistic regression to examine whether LAN at baseline was associated with the odds of developing obesity at follow-up (2004-2006). Outdoor LAN exposure was estimated from satellite imagery and obesity was measured based on self-reported weight and height.

RESULTS

We found that higher outdoor LAN at baseline was associated with higher odds of developing obesity over 10 years. Compared with the lowest quintile of LAN, the highest quintile was associated with 12% and 19% higher odds of developing obesity at follow-up in men (OR (95% CI) = 1.12 (1.00, 1.250)) and women (1.19 (1.04, 1.36)), respectively.

CONCLUSIONS

Our findings suggest that high LAN exposure could predict a higher risk of developing obesity in middle-to-older aged American adults.

Daily and Seasonal Variation in Light Exposure among the Old Order Amish

Exposure to artificial bright light in the late evening and early night, common in modern society, triggers phase delay of circadian rhythms, contributing to delayed sleep phase syndrome and seasonal affective disorder. Studying a unique population like the Old Order Amish (OOA), whose lifestyles resemble pre-industrial societies, may increase understanding of light’s relationship with health. Thirty-three participants (aged 25–74, mean age 53.5; without physical or psychiatric illnesses) from an OOA community in Lancaster, PA, were assessed with wrist-worn actimeters/light loggers for at least 2 consecutive days during winter/spring (15 January–16 April) and spring/summer (14 May–10 September). Daily activity, sleep–wake cycles, and their relationship with light exposure were analyzed. Overall activity levels and light exposure increased with longer photoperiod length. While seasonal variations in the amount and spectral content of light exposure were equivalent to those reported previously for non-Amish groups, the OOA experienced a substantially (~10-fold) higher amplitude of diurnal variation in light exposure (darker nights and brighter days) throughout the year than reported for the general population. This pattern may be contributing to lower rates of SAD, short sleep, delayed sleep phase, eveningness, and metabolic dysregulation, previously reported among the OOA population.

Circadian and Sleep Metabolomics Across Species

Under normal circadian function, metabolic control is temporally coordinated across tissues and behaviors with a 24-h period. However, circadian disruption results in negative consequences for metabolic homeostasis including energy or redox imbalances. Yet, circadian disruption has become increasingly prevalent within today's society due to many factors including sleep loss. Metabolic consequences of both have been revealed by metabolomics analyses of circadian biology and sleep. Specifically, two primary analytical platforms, mass spectrometry and nuclear magnetic resonance spectroscopy, have been used to study molecular clock and sleep influences on overall metabolic rhythmicity. For example, human studies have demonstrated the prevalence of metabolic rhythms in human biology, as well as pan-metabolome consequences of sleep disruption. However, human studies are limited to peripheral metabolic readouts primarily through minimally invasive procedures. For further tissue- and organism-specific investigations, a number of model systems have been studied, based upon the conserved nature of both the molecular clock and sleep across species. Here we summarize human studies as well as key findings from metabolomics studies using mice, Drosophila, and zebrafish. While informative, a limitation in existing literature is a lack of interpretation regarding dynamic synthesis or catabolism within metabolite pools. To this extent, future work incorporating isotope tracers, specific metabolite reporters, and single-cell metabolomics may provide a means of exploring dynamic activity in pathways of interest.

Megacities, migration and an evolutionary approach to bipolar disorder: a study of Sardinian immigrants in Latin America

Objective:

To determine whether people with a Sardinian genetic background who live in the megacities of South America have a higher frequency of hypomania than residents of Sardinia.

Methods:

A community survey of Sardinian immigrants was carried out in four Brazilian metropoles (n=218) and Buenos Aires (n=306). The results were compared with those of a study involving a similar methodology (Mood Disorder Questionnaire [MDQ] as a screening tool) conducted in seven Italian regions, including a sub-sample from Sardinia.

Results:

There was a higher prevalence of lifetime hypomania among Sardinians living in the Brazilian metropoles than among those living in Sardinia. This result was also consistent with Sardinian immigrants in Buenos Aires. After stratification by sex and age, the lifetime prevalence of MDQ scores ≥ 8 among Sardinians in South-American megacities and Sardinia was 8.6% vs. 2.9%, respectively (p < 0.0001).

Conclusions:

The higher frequency of hypomania in migrant populations appears to favor an evolutionary view in which mood disorders may be a maladaptive aspect of a genetic background with adaptive characteristics.

Coping with the New Era: Noise and Light Pollution, Hperactivity and Steroid Hormones. Towards an Evolutionary View of Bipolar Disorders

Human population is increasing in immense cities with millions of inhabitants, in which life is expected to run 24 hours a day for seven days a week (24/7). Noise and light pollution are the most reported consequences, with a profound impact on sleep patterns and circadian biorhythms. Disruption of sleep and biorhythms has severe consequences on many metabolic pathways. Suppression of melatonin incretion at night and the subsequent effect on DNA methylation may increase the risk of prostate and breast cancer. A negative impact of light pollution on neurosteroids may also affect mood. People who carry the genetic risk of bipolar disorder may be at greater risk of full-blown bipolar disorder because of the impact of noise and light pollution on sleep patterns and circadian biorhythms. However, living in cities may also offers opportunities and might be selective for people with hyperthymic temperament, who may find themselves advantaged by increased energy prompted by increased stimulation produced by life in big cities. This might result in the spreading of the genetic risk of bipolar disorder in the coming decades. In this perspective the burden of poor quality of life, increased disability adjusted life years and premature mortality due to the increases of mood disorders is the negative side of a phenomenon that in its globality also shows adaptive aspects. The new lifestyle also influences those who adapt and show behaviors, reactions and responses that might resemble the disorder, but are on the adaptive side.

BMAL1 Deficiency Contributes to Mandibular Dysplasia by Upregulating MMP3

Skeletal mandibular hypoplasia (SMH), one of the common types of craniofacial deformities, seriously affects appearance, chewing, pronunciation, and breathing. Moreover, SMH is prone to inducing obstructive sleep apnea syndrome. We found that brain and muscle ARNT-like 1 (BMAL1), the core component of the molecular circadian oscillator, was significantly decreased in mandibles of juvenile SMH patients. Accordingly, SMH was observed in circadian-rhythm-disrupted or BMAL1-deficient mice. RNA sequencing and protein chip analyses suggested that matrix metallopeptidase 3 (MMP3) is the potential target of BMAL1. Interestingly, in juvenile SMH patients, we observed that MMP3 was obviously increased. Consistently, MMP3 was upregulated during the whole growth period of 3-10 weeks in Bmal1-/- mice. Given these findings, we set out to characterize the underlying mechanism and found BMAL1 deficiency enhanced Mmp3 transcription through activating p65 phosphorylation. Together, our results provide insight into the mechanism by which BMAL1 is implicated in the pathogenesis of SMH.

Using light to tell the time of day: sensory coding in the mammalian circadian visual network

Circadian clocks are a near-ubiquitous feature of biology, allowing organisms to optimise their physiology to make the most efficient use of resources and adjust behaviour to maximise survival over the solar day. To fulfil this role, circadian clocks require information about time in the external world. This is most reliably obtained by measuring the pronounced changes in illumination associated with the earth's rotation. In mammals, these changes are exclusively detected in the retina and are relayed by direct and indirect neural pathways to the master circadian clock in the hypothalamic suprachiasmatic nuclei. Recent work reveals a surprising level of complexity in this sensory control of the circadian system, including the participation of multiple photoreceptive pathways conveying distinct aspects of visual and/or time-of-day information. In this Review, I summarise these important recent advances, present hypotheses as to the functions and neural origins of these sensory signals, highlight key challenges for future research and discuss the implications of our current knowledge for animals and humans in the modern world.

Shift in Food Intake and Changes in Metabolic Regulation and Gene Expression during Simulated Night-Shift Work: A Rat Model

Night-shift work is linked to a shift in food intake toward the normal sleeping period, and to metabolic disturbance. We applied a rat model of night-shift work to assess the immediate effects of such a shift in food intake on metabolism. Male Wistar rats were subjected to 8 h of forced activity during their rest (ZT2-10) or active (ZT14-22) phase. Food intake, body weight, and body temperature were monitored across four work days and eight recovery days. Food intake gradually shifted toward rest-work hours, stabilizing on work day three. A subgroup of animals was euthanized after the third work session for analysis of metabolic gene expression in the liver by real-time polymerase chain reaction (PCR). Results show that work in the rest phase shifted food intake to rest-work hours. Moreover, liver genes related to energy storage and insulin metabolism were upregulated, and genes related to energy breakdown were downregulated compared to non-working time-matched controls. Both working groups lost weight during the protocol and regained weight during recovery, but animals that worked in the rest phase did not fully recover, even after eight days of recovery. In conclusion, three to four days of work in the rest phase is sufficient to induce disruption of several metabolic parameters, which requires more than eight days for full recovery.

Nutritional aspects of night eating and its association with weight status among Korean adolescents

BACKGROUND/OBJECTIVES

A growing body of research has indicated that night eating could be associated with poor diet quality and negative health outcomes. This study examined the nutritional aspects of night eating, its related factors, and the association between night eating and body weight among Korean adolescents.

SUBJECTS/METHODS

This study analysed the data from a one day 24-hour dietary recall as well as a demographic survey of 1,738 Korean adolescents aged 12 to 18-years-old obtained from the 2010-2012 Korea National Health and Nutrition Examination Survey. 'Night eating' was defined as consuming 25% or more of one's daily energy intake between 21:00 and 06:00. Subjects complying with the preceding condition were classified as 'night eaters', whereas the rest were considered 'non-night eaters'. Logistic regression analysis examined factors related to night eating. Multiple linear regression analyses were used to examine the relationship between night eating and BMI z-scores, whereas multinomial logistic regression analysis was used to examine the relationship between night eating and weight status.

RESULTS

About 21% of Korean adolescents appeared to be night eaters. Night eaters showed increased breakfast skipping (P = 0.001), higher energy intake from snacks (P < 0.001), greater proportion of energy intake from fat (P = 0.029), and lower Dietary Diversity Scores (P = 0.008) than non-night eaters. Male adolescents presented 1.9 times higher odds of being night eaters than females. Adolescents whose both parents were night eaters were 4.4 times as likely to be night eaters as those whose neither parents were. Female adolescents showed a significant relationship between night eating and BMI z-scores (β = 0.28, P = 0.004). However, night eating did not increase odds of being overweight or obese in adolescents.

CONCLUSIONS

Night eating in Korean adolescents was related to undesirable dietary behaviours and low diet quality in general as well as higher BMI z-scores in females. Male gender and parental night eating appeared to be the factors that significantly increased odds of night eating. These results suggest that night eating should be considered when designing nutrition education or intervention programs targeting adolescents.

Environmental Light Exposure Is Associated with Increased Body Mass in Children

The timing, intensity, and duration of exposure to both artificial and natural light have acute metabolic and physiological effects in mammals. Recent research in human adults suggests exposure to moderate intensity light later in the day is concurrently associated with increased body mass; however, no studies have investigated the effect of light exposure on body mass in young children. We examined objectively measured light exposure and body mass of 48 preschool-aged children at baseline, and measured their body mass again 12 months later. At baseline, moderate intensity light exposure earlier in the day was associated with increased body mass index (BMI). Increased duration of light exposure at baseline predicted increased BMI 12-months later, even after controlling for baseline sleep duration, sleep timing, BMI, and activity. The findings identify that light exposure may be a contributor to the obesogenic environment during early childhood.

Natural environments, ancestral diets, and microbial ecology: is there a modern "paleo-deficit disorder"? Part II

Famed microbiologist René J. Dubos (1901–1982) was an early pioneer in the developmental origins of health and disease (DOHaD) construct. In the 1960s, he conducted groundbreaking research concerning the ways in which early-life experience with nutrition, microbiota, stress, and other environmental variables could influence later-life health outcomes. He recognized the co-evolutionary relationship between microbiota and the human host. Almost 2 decades before the hygiene hypothesis, he suggested that children in developed nations were becoming too sanitized (vs. our ancestral past) and that scientists should determine whether the childhood environment should be “dirtied up in a controlled manner.” He also argued that oft-celebrated growth chart increases via changes in the global food supply and dietary patterns should not be equated to quality of life and mental health. Here in the second part of our review, we reflect the words of Dubos off contemporary research findings in the areas of diet, the gut-brain-axis (microbiota and anxiety and depression) and microbial ecology. Finally, we argue, as Dubos did 40 years ago, that researchers should more closely examine the relevancy of silo-sequestered, reductionist findings in the larger picture of human quality of life. In the context of global climate change and the epidemiological transition, an allergy epidemic and psychosocial stress, our review suggests that discussions of natural environments, urbanization, biodiversity, microbiota, nutrition, and mental health, are often one in the same.

Obesity = physical activity + dietary intake + sleep stages + light exposure

Daily levels of physical activity and calories from dietary intake have been the focus of obesity prevention measures. Recent findings have made a twist in the line of thinking. The timing of physical exercise and that of dietary intake are also important to obesity prevention. Night-time sleep and exposure to light are therefore important targets of intervention.