CircadiPy: An open-source toolkit for analyzing chronobiology time series.

BACKGROUND: Chronobiology is the scientific field focused on studying periodicity in biological processes. In mammals, most physiological variables exhibit circadian rhythmicity, such as metabolism, body temperature, locomotor activity, and sleep. The biological rhythmicity can be statistically evaluated by examining the time series and extracting parameters that correlate to the period of oscillation, its amplitude, phase displacement, and overall variability. NEW METHOD: We have developed a library called CircadiPy, which encapsulates methods for chronobiological analysis and data inspection, serving as an open-access toolkit for the analysis and interpretation of chronobiological data. The package was designed to be flexible, comprehensive and scalable in order to assist research dealing with processes affected or influenced by rhythmicity. RESULTS: The results demonstrate the toolkit's capability to guide users in analyzing chronobiological data collected from various recording sources, while also providing precise parameters related to the circadian rhythmicity. COMPARISON WITH EXISTING METHODS: The analysis methodology from this proposed library offers an opportunity to inspect and obtain chronobiological parameters in a straightforward and cost-free manner, in contrast to commercial tools. CONCLUSIONS: Moreover, being an open-source tool, it empowers the community with the opportunity to contribute with new functions, analysis methods, and graphical visualizations given the simplified computational method of time series data analysis using an easy and comprehensive pipeline within a single Python object.

Understanding how cells and organisms keep time during development.

A classical question in biology is how different processes are controlled in space and time, with research pointing to different mechanisms as timers. In this collection of Voices, we asked researchers to define their scientific questions related to time-keeping and the approaches they use to answer them.

Threatened chronotopes: can chronobiology help endangered species?

Pittendrigh and Daan's 1976 article "Pacemaker structure: A clock for all seasons" marks the foundation of modern seasonal chronobiology. It proposed the internal coincidence model comprised of a Morning (M) and Evening (E) oscillator, which are coupled but synchronized separately by dawn and dusk. It has become an attractive model to explain the seasonal adaptation of circadian rhythms. Using the example of the European hamster, this article connects the classical entrainment concept to species decline and, ultimately, conservation concepts. Seasonality of this species is well studied and circannual rhythms have been described in at least 32 parameters. The European hamster is listed as critically endangered on the International Union for Conservation of Nature (IUCN) red list. Changes in the temporal structure of the environment (the chronotope) caused by climate change and light pollution might be responsible for the global decline. The article shows that classical chronobiological concepts such as the internal coincidence model (Pittendrigh and Daan Pittendrigh and Daan, J Comp Physiol [a] 106:333-355, 1976) are helpful to understand the (chronobiological) causes of the decline and can potentially support species conservation. Knowing the species' physiological limitations as well as its adaptation capacities can potentially prevent its extinction at a time when classical conservation concepts have reached their limits.

Coupled oscillator cooperativity as a control mechanism in chronobiology.

Control of dynamical processes is vital for maintaining correct cell regulation and cell-fate decisions. Numerous regulatory networks show oscillatory behavior; however, our knowledge of how one oscillator behaves when stimulated by two or more external oscillatory signals is still missing. We explore this problem by constructing a synthetic oscillatory system in yeast and stimulate it with two external oscillatory signals. Letting model verification and prediction operate in a tight interplay with experimental observations, we find that stimulation with two external signals expands the plateau of entrainment and reduces the fluctuations of oscillations. Furthermore, by adjusting the phase differences of external signals, one can control the amplitude of oscillations, which is understood through the signal delay of the unperturbed oscillatory network. With this we reveal a direct amplitude dependency of downstream gene transcription. Taken together, these results suggest a new path to control oscillatory systems by coupled oscillator cooperativity.

Do sex hormones confound or mediate the effect of chronotype on breast and prostate cancer? A Mendelian randomization study.

Morning-preference chronotype has been found to be protective against breast and prostate cancer. Sex hormones have been implicated in relation to chronotype and the development of both cancers. This study aimed to assess whether sex hormones confound or mediate the effect of chronotype on breast and prostate cancer using a Mendelian Randomization (MR) framework. Genetic variants associated with chronotype and sex hormones (total testosterone, bioavailable testosterone, sex hormone binding globulin, and oestradiol) (p<5×10-8) were obtained from published genome-wide association studies (n≤244,207 females and n≤205,527 males). These variants were used to investigate causal relationships with breast (nCases/nControls = 133,384/113,789) and prostate (nCases/nControls = 79,148/61,106) cancer using univariable, bidirectional and multivariable MR. In females, we found evidence for: I) Reduced risk of breast cancer per category increase in morning-preference (OR = 0.93, 95% CI:0. 88, 1.00); II) Increased risk of breast cancer per SD increase in bioavailable testosterone (OR = 1.10, 95% CI: 1.01, 1.19) and total testosterone (OR = 1.15, 95% CI:1.07, 1.23); III) Bidirectional effects between morning-preference and both bioavailable and total testosterone (e.g. mean SD difference in bioavailable testosterone = -0.08, 95% CI:-0.12, -0.05 per category increase in morning-preference vs difference in morning-preference category = -0.04, 95% CI: -0.08, 0.00 per SD increase in bioavailable testosterone). In males, we found evidence for: I) Reduced risk of prostate cancer per category increase in morning-preference (OR = 0.90, 95% CI: 0.83, 0.97) and II) Increased risk of prostate cancer per SD increase in bioavailable testosterone (OR = 1.22, 95% CI: 1.08, 1.37). No bidirectional effects were found between morning-preference and testosterone in males. While testosterone levels were causally implicated with both chronotype and cancer, there was inconsistent evidence for testosterone as a mediator of the relationship. The protective effect of morning-preference on both breast and prostate cancer is clinically interesting, although it may be difficult to effectively modify chronotype. Further studies are needed to investigate other potentially modifiable intermediates.

Chronobiological activity of cysteinyl leukotriene receptor 1 during basal and induced autophagy in the ARPE-19 retinal pigment epithelial cell line.

Autophagy is an important cellular mechanism for maintaining cellular homeostasis, and its impairment correlates highly with age and age-related diseases. Retinal pigment epithelial (RPE) cells of the eye represent a crucial model for studying autophagy, as RPE functions and integrity are highly dependent on an efficient autophagic process. Cysteinyl leukotriene receptor 1 (CysLTR1) acts in immunoregulation and cellular stress responses and is a potential regulator of basal and adaptive autophagy. As basal autophagy is a dynamic process, the aim of this study was to define the role of CysLTR1 in autophagy regulation in a chronobiologic context using the ARPE-19 human RPE cell line. Effects of CysLTR1 inhibition on basal autophagic activity were analyzed at inactive/low and high lysosomal degradation activity with the antagonists zafirlukast (ZTK) and montelukast (MTK) at a dosage of 100 nM for 3 hours. Abundances of the autophagy markers LC3-II and SQSTM1 and LC3B particles were analyzed in the absence and presence of lysosomal inhibitors using western blot analysis and immunofluorescence microscopy. CysLTR1 antagonization revealed a biphasic effect of CysLTR1 on autophagosome formation and lysosomal degradation that depended on the autophagic activity of cells at treatment initiation. ZTK and MTK affected lysosomal degradation, but only ZTK regulated autophagosome formation. In addition, dexamethasone treatment and serum shock induced autophagy, which was repressed by CysLTR1 antagonization. As a newly identified autophagy modulator, CysLTR1 appears to be a key player in the chronobiological regulation of basal autophagy and adaptive autophagy in RPE cells.

The Importance of Being a 'Lark' in Post-Menopausal Women with Obesity: A Ploy to Prevent Type 2 Diabetes Mellitus?

Chronotype is defined as the behavioral manifestation of circadian rhythms related to the external light-dark cycle. Evening chronotype has been associated with an increased risk of developing cardiometabolic diseases in obesity. Menopause is a lifestage associated with an increased risk of developing cardiometabolic diseases and a change in circadian rhythmicity compared to pre-menopause. However, the prevalence of chronotype categories in menopause and their role in determining menopause-related cardiometabolic risk, mostly in obesity, have not been investigated. Thus, we aimed to investigate the prevalence of chronotype categories in post-menopausal women with obesity and their role in menopause-related cardiometabolic risk. In this cross-sectional study we enrolled 49 pre-menopausal and 74 post-menopausal women with obesity. Anthropometric parameters, lifestyle habits, adherence to the Mediterranean Diet (MD), sleep quality, chronotype and the presence of type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVD) were studied. No significance differences were detected in terms of lifestyle and adherence to the MD between pre- and post-menopausal women. Chronotype was classified as morning in 66 (53.6%), evening in 20 (16.3%) and intermediate in 37 (30.1%) women. In addition, pre-menopausal women with obesity showed a significantly higher chance to have an intermediate chronotype (OR = 2.21, 95% CI 1.28-3.83; p = 0.004), whereas post-menopausal women with obesity showed a trend to have a higher morning chronotype (OR = 1.42, 95% CI 0.98-2.06; p = 0.051), although this did not reach statistical significance. No significant differences were detected in terms of prevalence of evening chronotype between the two groups. However, the evening chronotype had a significantly higher risk to have T2DM compared to the morning (OR = 17.29, 95% CI 2.40-124.27; p = 0.005) and intermediate chronotypes (OR = 30.86, 95% CI 2.05-464.32; p = 0.013) in both pre- and post-menopausal women with obesity. In conclusion, the intermediate chronotype was significantly more prevalent in pre-menopausal women with obesity compared to post-menopausal women. Evening chronotype was associated to T2DM in both pre- and post-menopause. These results support the importance of including the assessment of chronotype in the management of women with obesity in post-menopause.

Do Temporal Eating Patterns Differ in Healthy versus Unhealthy Overweight/Obese Individuals?

This study examined whether the temporal patterns of energy and macronutrient intake in early and late eating windows were associated with metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) among non-shift workers. A total of 299 overweight/obese non-shift workers (Age: 40.3 ± 6.9 years; 73.6% women; BMI: 31.7 ± 5.0 kg/m2) were recruited in the Klang Valley area of Malaysia. The biochemical parameters were determined from fasting blood samples, whereas information on dietary intake and timing was obtained from a 7-day diet history questionnaire. The midpoint of eating was used to determine the early and late windows. Compared to MHO non-shift workers (n = 173), MUO non-shift workers (n = 126) had lower energy intake from carbohydrates and protein during the early window. In contrast, MUO participants had greater energy intake from carbohydrates and fat during the late window. Participants with unhealthy metabolic status (regardless of their chronotypes) had similar temporal patterns of energy intake characterized by smaller energy intake during the early window and greater energy intake during the late window compared with participants with healthier metabolic status. Overall, the lowest percentile of energy intake during the early window was associated with an increased risk of MUO, after adjustment for potential confounders [odds ratio (OR) = 4.30, 95% confidence interval (CI) 1.41-13.11]. The greater the energy intake during the late window, the greater the risk of MUO (OR = 2.38, 95% CI 1.11-5.13) (OR = 2.33, 95% CI 1.03-5.32) (OR = 4.45, 95% CI 1.71-11.56). In summary, consuming less energy earlier in the day and more energy and carbohydrate later in the day was associated with a greater risk of MUO. Thus, a prospective study is needed to explore the potential role of chrono-nutrition practices in modifying risk factors to delay the transition of MHO to MUO.

Circadian clock, carcinogenesis, chronochemotherapy connections.

The circadian clock controls the expression of nearly 50% of protein coding genes in mice and most likely in humans as well. Therefore, disruption of the circadian clock is presumed to have serious pathological effects including cancer. However, epidemiological studies on individuals with circadian disruption because of night shift or rotating shift work have produced contradictory data not conducive to scientific consensus as to whether circadian disruption increases the incidence of breast, ovarian, prostate, or colorectal cancers. Similarly, genetically engineered mice with clock disruption do not exhibit spontaneous or radiation-induced cancers at higher incidence than wild-type controls. Because many cellular functions including the cell cycle and cell division are, at least in part, controlled by the molecular clock components (CLOCK, BMAL1, CRYs, PERs), it has also been expected that appropriate timing of chemotherapy may increase the efficacy of chemotherapeutic drugs and ameliorate their side effect. However, empirical attempts at chronochemotherapy have not produced beneficial outcomes. Using mice without and with human tumor xenografts, sites of DNA damage and repair following treatment with the anticancer drug cisplatin have been mapped genome-wide at single nucleotide resolution and as a function of circadian time. The data indicate that mechanism-based studies such as these may provide information necessary for devising rational chronochemotherapy regimens.

The Effect of Four Weeks Dietary Intervention with 8-Hour Time-Restricted Eating on Body Composition and Cardiometabolic Risk Factors in Young Adults.

Recently, intermittent fasting, also known as time-restricted eating (TRE), has become a popular diet trend. Compared to animal studies, there have been few studies and inconclusive findings investigating the effects of TRE in humans. In this study, we examined the effects of 8 h TRE on body weight and cardiometabolic risk factors in young adults who were mainly active at night. A total of 33 young adults completed the 8 h TRE for 4 weeks. Body composition was measured by bioelectrical impedance analysis at baseline and every 2 weeks, and blood samples were collected at baseline and week 4. Daily dietary records were logged throughout the intervention period. Participants experienced significant changes in body weight (-1.0 ± 1.4 kg), body mass index (-0.4 ± 0.5 kg/m2), and body fat (-0.4 ± 1.9%) after 4 weeks of TRE. When participants were divided into weight loss/gain groups based on their weight change in week 4, fat mass reduction was significantly higher in the weight loss group than in the weight gain group. Regarding cardiometabolic risk factors, levels of fasting insulin and insulin resistance improved in the weight loss group after intervention, but not in the weight gain group. All subjects showed late-shifted sleeping patterns, but no significant differences in sleep duration, sleep quality, or psychological measures between the two groups. When meal frequency and energy proportion were evaluated, the average meal frequency was 2.8 ± 0.5 and energy proportions of breakfast, lunch, dinner, and snacks were 4.5, 39.2, 37.6, and 18.5%, respectively; there were no significant differences between the two groups. However, the saturated fat intake at dinner was lower in the weight loss group (3.1 ± 3.2%, 6.0 ± 2.5% respectively). In conclusion, 8 h TRE can be applied as a lifestyle strategy to manage body weight and cardiometabolic risk factors among young adults with late chronotypes.

Dietary Polyphenol Intake Is Associated with Biological Aging, a Novel Predictor of Cardiovascular Disease: Cross-Sectional Findings from the Moli-Sani Study.

Biological aging, or the discrepancy between biological and chronological age of a subject (Δage), has been associated with a polyphenol-rich Mediterranean diet and represents a new, robust indicator of cardiovascular disease risk. We aimed to disentangle the relationship of dietary polyphenols and total antioxidant capacity with Δage in a cohort of Italians. A cross-sectional analysis was performed on a sub-cohort of 4592 subjects (aged ≥ 35 y; 51.8% women) from the Moli-sani Study (2005-2010). Food intake was recorded by a 188-item food-frequency questionnaire. The polyphenol antioxidant content (PAC)-score was constructed to assess the total dietary content of polyphenols. Total antioxidant capacity was measured in foods by these assays: trolox equivalent antioxidant capacity (TEAC), total radical-trapping antioxidant parameter (TRAP) and ferric reducing-antioxidant power (FRAP). A deep neural network, based on 36 circulating biomarkers, was used to compute biological age and the resulting Δage, which was tested as outcome in multivariable-adjusted linear regressions. Δage was inversely associated with the PAC-score (ß = -0.31; 95%CI -0.39, -0.24) but not with total antioxidant capacity of the diet. A diet rich in polyphenols, by positively contributing to deceleration of the biological aging process, may exert beneficial effects on the long-term risk of cardiovascular disease and possibly of bone health.

In vitro gastrointestinal digestion and simulated colonic fermentation of pistachio nuts determine the bioaccessibility and biosynthesis of chronobiotics.

Chronodisruption leads to obesity and other metabolic disorders that can be alleviated by food-derived potential chronobiotics, such as phytomelatonin (PMT), phenolic compounds (PCs) and dietary fiber rich pistachios. Pistachios with (PN + SC) or without (PN) the seed coat were investigated for their in vitro chronobiotic potential since they are one of the main reported PMT sources. Consequently we evaluated the bioaccessibility, permeability, and biosynthesis of pistachio chronobiotics, particularly PMT, during gastrointestinal and colonic fermentation. The maximum in vitro bioaccessibility and apparent permeability (efflux-prone) of PCs, flavonoids and PMT were sample-specific [∼1.3% (both), 27 and 3.4% (PN + SC)], but additional amounts (flavonoids > PCs > PMT) were released under simulated colonic conditions. Short-chain fatty acids (SCFAs; 38 mM; >50% butyrate, PN + SC > PN) and some metabolites (e.g., indole, benzaldehyde, phenolic acids, and aliphatic/aromatic hydrocarbons) were detected depending on the sample. The predominant pistachio butyrate production during in vitro colonic fermentation can improve chronodisruption and benefit obese individuals. Pistachio's digestion increases the bioaccessibility and intestinal permeability of potential chronobiotics (PMT and PCs) and the biosynthesis of colonic metabolites (SCFAs, among others) also with chronobiotic potential.

Chronobiology of Natriuretic Peptides and Blood Pressure in Lean and Obese Individuals.

BACKGROUND: Diurnal variation of natriuretic peptide (NP) levels and its relationship with 24-h blood pressure (BP) rhythm has not been established. Obese individuals have a relative NP deficiency and disturbed BP rhythmicity. OBJECTIVES: This clinical trial evaluated the diurnal rhythmicity of NPs (B-type natriuretic peptide [BNP], mid-regional pro-atrial natriuretic peptide [MR-proANP], N-terminal pro-B-type natriuretic peptide [NT-proBNP]) and the relationship of NP rhythm with 24-h BP rhythm in healthy lean and obese individuals. METHODS: On the background of a standardized diet, healthy, normotensive, lean (body mass index 18.5 to 25 kg/m2) and obese (body mass index 30 to 45 kg/m2) individuals, age 18 to 40 years, underwent 24-h inpatient protocol involving ambulatory BP monitoring starting 24 h prior to the visit, controlled light intensity, and repeated blood draws for assessment of analytes. Cosinor analysis of normalized NP levels (normalized to 24-h mean value) was conducted to assess the diurnal NP rhythm and its relationship with systolic BP. RESULTS: Among 52 participants screened, 40 participants (18 lean, 22 obese; 50% women; 65% Black) completed the study. The median range spread (percentage difference between the minimum and maximum values) over 24 h for MR-proANP, BNP, and NT-proBNP levels was 72.0% (interquartile range [IQR]: 50.9% to 119.6%), 75.5% (IQR: 50.7% to 106.8%), and 135.0% (IQR: 66.3% to 270.4%), respectively. A cosine wave-shaped 24-h oscillation of normalized NP levels (BNP, MR-proANP, and NT-proBNP) was noted both in lean and obese individuals (prhythmicity <0.05 for all). A larger phase difference between MR-proANP BP rhythm (-4.9 h vs. -0.7 h) and BNP BP rhythm (-3.3 h vs. -0.9 h) was seen in obese compared with lean individuals. CONCLUSIONS: This human physiological trial elucidates evidence of diurnal NP rhythmicity and the presence of an NP-BP rhythm axis. There exists a misalignment of the NP-BP diurnal rhythm in the obese, which may contribute to the disturbed diurnal BP pattern observed among obese individuals. (The Diurnal Rhythm in Natriuretic Peptide Levels; NCT03834168).

Closing the protein gap in plant chronobiology.

Our modern understanding of diel cell regulation in plants stems from foundational work in the late 1990s that analysed the dynamics of selected genes and mutants in Arabidopsis thaliana. The subsequent rise of transcriptomics technologies such as microarrays and RNA sequencing has substantially increased our understanding of anticipatory (circadian) and reactive (light- or dark-triggered) diel events in plants. However, it is also becoming clear that gene expression data fail to capture critical events in diel regulation that can only be explained by studying protein-level dynamics. Over the past decade, mass spectrometry technologies and quantitative proteomic workflows have significantly advanced, finally allowing scientists to characterise diel protein regulation at high throughput. Initial proteomic investigations suggest that the diel transcriptome and proteome generally lack synchrony and that the timing of daily regulatory events in plants is impacted by multiple levels of protein regulation (e.g., post-translational modifications [PTMs] and protein-protein interactions [PPIs]). Here, we highlight and summarise how the use of quantitative proteomics to elucidate diel plant cell regulation has advanced our understanding of these processes. We argue that this new understanding, coupled with the extraordinary developments in mass spectrometry technologies, demands greater focus on protein-level regulation of, and by, the circadian clock. This includes hitherto unexplored diel dynamics of protein turnover, PTMs, protein subcellular localisation and PPIs that can be masked by simple transcript- and protein-level changes. Finally, we propose new directions for how the latest advancements in quantitative proteomics can be utilised to answer outstanding questions in plant chronobiology.

Cycles in epilepsy.

Epilepsy is among the most dynamic disorders in neurology. A canonical view holds that seizures, the characteristic sign of epilepsy, occur at random, but, for centuries, humans have looked for patterns of temporal organization in seizure occurrence. Observations that seizures are cyclical date back to antiquity, but recent technological advances have, for the first time, enabled cycles of seizure occurrence to be quantitatively characterized with direct brain recordings. Chronic recordings of brain activity in humans and in animals have yielded converging evidence for the existence of cycles of epileptic brain activity that operate over diverse timescales: daily (circadian), multi-day (multidien) and yearly (circannual). Here, we review this evidence, synthesizing data from historical observational studies, modern implanted devices, electronic seizure diaries and laboratory-based animal neurophysiology. We discuss advances in our understanding of the mechanistic underpinnings of these cycles and highlight the knowledge gaps that remain. The potential clinical applications of a knowledge of cycles in epilepsy, including seizure forecasting and chronotherapy, are discussed in the context of the emerging concept of seizure risk. In essence, this Review addresses the broad question of why seizures occur when they occur.

Sleep quality does not mediate the negative effects of chronodisruption on body composition and metabolic syndrome in healthcare workers in Ecuador.

BACKGROUND AND AIMS: The objective of the present work was to determine to what extent sleep quality may mediate the association between chronodisruption (CD) and metabolic syndrome (MS), and between CD and body composition (BC). METHODOLOGY: Cross-sectional study which included 300 adult health workers, 150 of whom were night shift workers and thereby exposed to CD. Diagnosis of MS was made based on Adult Treatment Panel III criteria. Sleep quality was measured using the Pittsburgh Sleep Quality Index. Body mass index (BMI), fat mass percentage, and visceral fat percentage were measured as indicators of body composition (BC). Data were analyzed using logistic, linear regression and structural equation models. RESULTS: The odds of health workers exposed to CD to suffer MS was 22.13 (IC95 8.68-66.07) when the model was adjusted for age, gender, physical activity and energy consumption. CD was also significantly associated with an increase in fat mass and visceral fat percentages, but not to BMI. Surprisingly, there was not enough evidence supporting the hypothesis that sleep quality contributes to the association between CD and MS or between CD and BC. CONCLUSIONS: Sleep quality does not mediate the negative effects of CD on MS nor on BC.

Sleep timing, chronotype and social jetlag: Impact on cognitive abilities and psychiatric disorders.

Sleep timing is controlled by the subtle interplay between circadian and homeostatic oscillators which, according to their endogenous properties, allow beings to feel spontaneously that it is time to go to bed or wake up in synchrony with the earth's light/dark cycle. In humans, however, social time and nocturnal artificial light modify sleep timing. Our modern lifestyle and artificial nocturnal light delay our bedtime, make us wake up, and lead to a greater intraindividual variability in sleep timing. Depending on the constraints that social time places on us, our sleep timing may be in or out of phase with the internal circadian timing determined by the circadian clock. When a person's social time is out of phase with their circadian time, they may be considered to suffer from circadian disruption or 'social jetlag'. There are interindividual differences in sleep timing that are known as morningness-eveningness preferences or chronotype, e.g. late chronotypes go to bed later. Chronotype may be assessed in terms of differences in kinetic homeostatic sleep pressure, intrinsic circadian period (ICP) and/or phase angle entrainment. In addition, chronotype depends on genetic and age-related factors, e.g. it gets earlier as people grow older. The social time of late chronotype individuals during week days is not adapted to their circadian time, unlike on free days. This results in social jetlag and circadian disruption, which in turn induces a chronic sleep debt due to a late bedtime and an early wake time, which is compensated on free days but only partially. Sleep and circadian clock disruption generally alter cognitive performance (alertness, attention, memory, higher-order executive functions such as response inhibition and decision-making) but their impact remains to be clarified. When subjects adopt their preferred sleep timing, a "synchrony effect" often appears with chronotypes performing better during daytime at optimal than at suboptimal timing (late chronotypes perform better in the evening, early chronotypes in the morning). Evening types appear to be cognitively more vulnerable to suboptimal times than morning types, probably because they have to deal with social jetlag and the "wake effort" period after awakening. Circadian disruption, but not chronotype, may impact attentional/inhibitory performance (more impulsivity and inattention). Strong associations have been found between mood disorders or attention deficit hyperactivity disorder (ADHD) and chronotype, with these psychiatric disorders typically being overrepresented in evening types. The association between social jetlag and these psychiatric disorders is less obvious. Social jetlag can be corrected by reducing exposure to evening light, although eveningness may be considered as a lifelong factor predisposing to depression or inattention.