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Introduction: Fragmented REM sleep may impede overnight resolution of distress and increase depressive symptoms. Furthermore, both fragmented REM and depressive symptoms may share a common genetic factor. We explored the associations between REM sleep fragmentation, depressive symptoms, and a polygenic risk score (PRS) for depression among adolescents., Methods: About 161 adolescents (mean age 16.9 ± 0.1 years) from a birth cohort underwent a sleep EEG and completed the Beck Depression Inventory-II the same day. We calculated PRSes for depressive symptoms with PRSice 1.25 software using weights from a recent genome-wide association study for dimensions of depressive symptoms (negative emotion, lack of positive emotion and somatic complaints). REM fragmentation in relation to entire REM duration was manually calculated from all REM epochs. REM latency and density were derived using SomnoMedics DOMINO software., Results: PRSes for somatic complaints and lack of positive emotions were associated with higher REM fragmentation percent. A higher level of depressive symptoms was associated with increased percent of REM fragmentation and higher REM density, independently of the genetic risks. Belonging to the highest decile in depressive symptoms was associated with a 2.9- and 7.6-fold risk of belonging to the highest tertile in REM fragmentation and density. In addition, higher PRS for somatic complaints had an independent, additive effect on increased REM fragmentation., Limitation: A single night's sleep EEG was measured, thus the night-to-night stability of the REM fragmentation-depressive symptom link is unclear., Conclusion: Depressive symptoms and genetic risk score for somatic complaints are independently associated with more fragmented REM sleep. This offers new insights on the quality of sleep and its relation to adolescents' mood., (Copyright © 2018. Published by Elsevier B.V.)

Schizophrenia has been associated with disturbed sleep, even before the onset of the disorder, and also in non-schizophrenic first-order relatives. This may point to an underlying genetic influence. Here we examine whether weighted polygenic risk scores (PRS) for schizophrenia are associated with sleep spindle activity in healthy adolescents. Our sample comes from a community-based cohort of 157 non-schizophrenic adolescents (57% girls) having both genetic data and an overnight sleep EEG measurement available. Based on a recent genome-wide association study, we calculated PRS for schizophrenia across the whole genome. We also calculated PRS for the CACNA1l gene region, which has been associated with both schizophrenia and sleep spindle formation. We performed an overnight sleep EEG at the homes of the participants. Stage two sleep spindles were detected using an automated algorithm. Sleep spindle amplitude, duration, intensity and density were measured separately for central and frontal derivations and for fast (13-16 Hz) and slow (10-13 Hz) spindles. PRS for schizophrenia was associated with higher fast spindle amplitude (p = 0.04), density (p = 0.006) and intensity (p = 0.04) at the central derivation, and PRS in the CACNA1l region associated with higher slow spindle amplitude (p = 0.01), duration (p = 0.03) and intensity (p = 0.002) at the central derivation. A positive association between genetic variants for schizophrenia and sleep spindle activity among healthy adolescents supports a view that sleep spindles and schizophrenia share similar genetic pathways. This study suggests that altered sleep spindle activity might serve as an endophenotype of schizophrenia., (© 2018 European Sleep Research Society.)

Objective: Diagnosed autism spectrum disorders have been associated with a high prevalence of sleep problems, other psychiatric disorders and social deficits in adolescence. However, little is known about the possible connection between subclinical autistic traits and sleep. This study explored whether adolescents with elevated levels of subclinical autistic traits are at heightened risk for sleep problems., Methods: This study used data from the community cohort born in 1998. The sample consisted of 157 (57% girls) 17-year-old adolescents. Autistic traits were assessed using the Autism Spectrum Quotient (AQ). The Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), and the Adult ADHD Self-Report Scale were utilized to control for comorbid psychiatric symptoms. Sleep was measured with actigraphy and sleep quality was self-rated using the Pittsburgh Sleep Quality Index (PSQI). Associations between autistic traits and sleep were examined using logistic regression analysis., Results: Elevated levels of autistic traits were significantly associated with shorter weekday sleep duration. Moreover, autistic traits remained an independent predictor of short sleep duration when comorbid psychiatric symptoms were controlled for (OR 1.14; 95% CI: 1.03-1.26)., Conclusions: The results suggest that subclinical autistic traits should be considered as a possible underlying mechanism affecting adolescent sleep., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Research suggests an association between schizophrenia and a decrease in sleep spindle activity, as well as a change in sleep architecture. It is unknown how the continuum of psychotic symptoms relates to different features in the sleep electroencephalogram. We set out to examine how sleep architecture and stage 2 spindle activity are associated with schizotypy in a healthy adolescent population. The participants in our study (n = 176, 61% girls) came from a community-based cohort. Schizotypal traits were evaluated using the Schizotypal Personality Scale (STA) in early adolescence (mean age 12.3 years, SD = 0.5) and the participants underwent ambulatory overnight polysomnography at mean age 16.9 years (SD = 0.1). Sleep was scored in 30-s epochs into stages 1, 2, 3 and rapid eye movement (REM) sleep. Stage 2 spindles were detected using an automated algorithm. Spindle analyses from central and frontal derivations included spindle duration and density for slow (10-13 Hz) and fast (13-16 Hz) ranges. Covariates included sex and age. Those with the highest STA scores had a higher percentage of REM (B = 2.07 [95% CI, 0.17, 4.0]; p = .03) than those with the lowest scores. Those with the highest scores had shorter spindle duration, as derived from the frontal regions, and a slower oscillation range (B = -0.04 [95% CI, -0.07, -0.01]; p = .023) than those with the lowest scores. We conclude that high levels of schizotypy characteristics measured in early adolescence may be associated with distinguished features of sleep architecture, namely with spindle morphology and a higher proportion of REM sleep., (© 2018 European Sleep Research Society.)

Background: Sleep facilitates the extraction of semantic regularities amongst newly encoded memories, which may also lead to increased false memories. We investigated sleep stage proportions and sleep spindles in the recollection of adolescents' false memories, and their potential sex-specific differences., Methods: 196 adolescents (mean age 16.9 y; SD = 0.1, 61% girls) underwent the Deese, Roediger & McDermott (DRM) false memory procedure and overnight polysomnography, with free recall the following morning. Sleep was scored manually into stages 1, 2, 3 and REM. Stage 2 sleep spindle frequency, density, and peak amplitude were used as measures of spindle activity for slow (10-13 Hz) and fast (13-16 Hz) ranges., Results: In girls, a lower number of critical lures was associated with higher spindle frequency (p ≤ 0.01), density (p ≤ 0.01), and amplitude (p = 0.03). Additionally, girls' longer sleep duration was associated with more intrusion words (p = 0.03), but not with critical lures. These associations survived adjustment for age, pubertal status, and intelligence. No significant results emerged in boys., Conclusions: In adolescent girls, higher spindle activity was associated with fewer critical lures being falsely recalled in the DRM paradigm. Unlike studies using adult participants, we did not observe any association between slow-wave sleep and false memory recollection., (Crown Copyright © 2018. Published by Elsevier Inc. All rights reserved.)

ADHD and its subclinical symptoms have been associated with both disturbed sleep and weakened overnight memory consolidation. As sleep spindle activity during NREM sleep plays a key role in both sleep maintenance and memory consolidation, we examined the association between subclinical ADHD symptoms and sleep spindle activity. Furthermore, we hypothesized that sleep spindle activity mediates the effect of ADHD symptoms on overnight learning outcome in a procedural memory task. We studied these questions in a community-based cohort of 170 adolescents (58% girls, mean age = 16.9, SD = 0.1 years), who filled in the Adult ADHD Self-Report Scale (ASRS-v1.1), and underwent an overnight sleep EEG coupled with a mirror tracing task before and after sleep. Elevated ADHD symptoms were associated with weaker fast sleep spindle activity, and poorer overnight learning in the procedural memory test. However, sleep spindles, contrary to the hypothesis, did not mediate the association between ADHD symptoms and overnight learning. Our results showed that a higher level of ADHD symptoms in adolescence is associated with similar alterations in sleep spindle activity as observed in many neuropsychiatric conditions and might contribute to altered synaptic connectivity and sleep fragmentation observed in ADHD., (Copyright © 2018. Published by Elsevier Inc.)

Objective: Recent genome-wide association studies (GWASs) have revealed new genetic variants behind self-reported individual circadian preference, a distinct biological trait that is fairly stable during adulthood. In this study we analyze whether these genetic variants associate with objectively measured sleep timing from childhood to adolescence, over a nine-year period, with self-reported circadian preference during late adolescence., Methods: The participants (N = 100, 61% girls) came from a community cohort from Finland born in 1998. Sleep midpoint was measured with actigraphy at 8, 12 and 17 years. Circadian preference was self-reported at the age of 17 years. Single nucleotide polymorphisms (SNPs) were extracted at 12 years of age from the Illumina OmniExpress Exome 1.2 bead array data. Weighted polygenic risk scores (PRSs) were calculated based on top SNPs from a recent GWAS for morningness-eveningness in an adult population., Results: The PRS for circadian preference towards morningness was associated with earlier sleep midpoint from childhood to adolescence. When the time points were analyzed separately, the association between genetic tendency towards morning preference and earlier sleep midpoint was strongest among the 17-year-olds. Furthermore, the shift towards later sleep rhythm from early to late adolescence was milder for those with a higher PRS for morning preference. PRS for morning preference was also associated with self-reported circadian preference towards morningness in late adolescence., Conclusion: Our results suggest that genetic variants found for circadian preference in adults are already associated with objective sleep timing during childhood and adolescence, and predict individual developmental sleep trajectories from childhood onwards., (Copyright © 2018. Published by Elsevier B.V.)

Background: Environmentally growing pathogens present an increasing threat for human health, wildlife and food production. Treating the hosts with antibiotics or parasitic bacteriophages fail to eliminate diseases that grow also in the outside-host environment. However, bacteriophages could be utilized to suppress the pathogen population sizes in the outside-host environment in order to prevent disease outbreaks. Here, we introduce a novel epidemiological model to assess how the phage infections of the bacterial pathogens affect epidemiological dynamics of the environmentally growing pathogens. We assess whether the phage therapy in the outside-host environment could be utilized as a biological control method against these diseases. We also consider how phage-resistant competitors affect the outcome, a common problem in phage therapy. The models give predictions for the scenarios where the outside-host phage therapy will work and where it will fail to control the disease. Parameterization of the model is based on the fish columnaris disease that causes significant economic losses to aquaculture worldwide. However, the model is also suitable for other environmentally growing bacterial diseases., Results: Transmission rates of the phage determine the success of infectious disease control, with high-transmission phage enabling the recovery of the host population that would in the absence of the phage go asymptotically extinct due to the disease. In the presence of outside-host bacterial competition between the pathogen and phage-resistant strain, the trade-off between the pathogen infectivity and the phage resistance determines phage therapy outcome from stable coexistence to local host extinction., Conclusions: We propose that the success of phage therapy strongly depends on the underlying biology, such as the strength of trade-off between the pathogen infectivity and the phage-resistance, as well as on the rate that the phages infect the bacteria. Our results indicate that phage therapy can fail if there are phage-resistant bacteria and the trade-off between pathogen infectivity and phage resistance does not completely inhibit the pathogen infectivity. Also, the rate that the phages infect the bacteria should be sufficiently high for phage-therapy to succeed.

Objectives: To assess differences relating to circadian preference in objectively measured sleep patterns from childhood to adolescence over a 9-year period. We hypothesized there is developmental continuity in sleep timing and duration according to circadian preference., Study Design: Young participants (N = 111, 65% girls) from a community-based birth cohort underwent sleep actigraphy at mean ages 8.1 (SD = 0.3), 12.3 (SD = 0.5), and 16.9 (SD = 0.1) years. A short version of Morningness-Eveningness Questionnaire was administered in late adolescence. At each follow-up, sleep midpoint, duration, wake after sleep onset, sleep efficiency, and weekend catch-up sleep were compared between those reporting morning, intermediate, and evening preferences in late adolescence., Results: Mixed model analyses indicated that sleep timing was significantly earlier among morning types compared with evening types at all ages (P values < .04). The mean differences in sleep midpoint between morning and evening types increased from a mean of 19 minutes (age 8), 36 minutes (age 12), to 89 minutes (age 17). The largest change occurred from age 12 to 17 years. Sleep duration, wake after sleep onset, sleep efficiency, and catch-up sleep did not differ according to circadian preference., Conclusions: This study found significant continuity in sleep timing from childhood to adolescence over 9 years, indicating that late circadian preference reported in late adolescence begins to manifest in middle childhood. Further studies are needed to establish whether sleep timing has its origins at an even earlier age., (Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.)

The seasonal pattern for mood and behaviour, the behavioural trait of morningness-eveningness, and sleep are interconnected features, that may serve as etiological factors in the development or exacerbation of medical conditions. Methods: The study was based on a random sample of inhabitants aged 25 to 74 years living in Finland. As part of the national FINRISK 2012 study participants were invited (n=9905) and asked whether the doctor had diagnosed or treated them during the past 12 months for chronic diseases. Results: A total of 6424 participants filled in the first set of questionnaires and 5826 attended the physical health status examination, after which the second set of questionnaires were filled. Regression models were built in which each condition was explained by the seasonal, diurnal and sleep features, after controlling for a range of background factors. Of the chronic diseases, depressive disorder was associated with longer total sleep duration ( p <.0001) and poor sleep quality ( p <.0001). Of the measurements for health status assessment, none associated with sleep features, but systolic blood pressure yielded significant ( p <.0001) associations with both seasonal and diurnal features at large. Conclusion: Sleep quality was the most sensitive probe in yielding associations with chronic diseases in this population-based study. The seasonal variations in mood and social activity, and the ease in getting up and tiredness in the morning were the most sensitive probes in yielding associations with blood pressure and waist circumference. Assessment of sleep quality, seasonal and diurnal features provides thus added value for health surveys of the general population.

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Individual circadian preference types and sleep EEG patterns related to spindle characteristics, have both been associated with similar cognitive and mental health phenotypes. However, no previous study has examined whether sleep spindles would differ by circadian preference. Here, we explore if spindle amplitude, density, duration or intensity differ by circadian preference and whether these associations are moderated by spindle location, frequency, and time distribution across the night. The participants (N = 170, 59% girls; mean age = 16.9, SD = 0.1 years) filled in the shortened 6-item Horne-Östberg Morningness-Eveningness Questionnaire. We performed an overnight sleep EEG at the homes of the participants. In linear mixed model analyses, we found statistically significant lower spindle amplitude and intensity in the morning as compared to intermediate (P < 0.001) and evening preference groups (P < 0.01; P > 0.06 for spindle duration and density). Spindle frequency moderated the associations (P < 0.003 for slow (<13 Hz); P > 0.2 for fast (>13 Hz)). Growth curve analyses revealed a distinct time distribution of spindles across the night by the circadian preference: both spindle amplitude and intensity decreased more towards morning in the morning preference group than in other groups. Our results indicate that circadian preference is not only affecting the sleep timing, but also associates with sleep microstructure regarding sleep spindle phenotypes.

Self-reported eveningness has been previously associated with depressed mood among adults and adolescents. Here, we study how circadian indicators based on actigraphic data differ between depressed and healthy adolescent boys. Our sample consisted of 17 medication-free adolescent boys, aged 14.5 to 17.5 years, of which eight had depressive disorder and were currently depressed and nine were healthy comparison participants. Psychiatric assessment was conducted by diagnostic interviews and complemented with observer-rating and self-rating scales. Actigraphic data were collected with wrist actigraphs for a minimum period of 25 consecutive days (range of 25 to 44 days). The behavioral trait of morningness-eveningness was measured with the 19-item Horne-Östberg Morningness-Eveningness Questionnaire. Based on the self-report, the depressed boys were more prone to eveningness than healthy controls, but based on the actigraphic data, they had earlier phases especially on school days and lower activity levels especially on weekends. On weekends, the depressed boys showed a greater shift toward later-timed phases than healthy controls. Our results confirm a mismatch of the subjective morningness-eveningness preference (late-preference) and the objective rest-activity rhythm (early-prone) during school days in depressed adolescent boys.

Circadian preference toward eveningness has been associated with increased risk for mental health problems both in early adolescence and in adulthood. However, in late adolescence, when circadian rhythm naturally shifts to later, its significance for mental health is not clear. Accordingly, we studied how circadian rhythm estimated both by self-reported chronotype and by actigraph-defined midpoint of sleep was associated with self-reported psychiatric problems based on Youth Self Report (YSR). The study builds on a community cohort born in 1998, Helsinki, Finland. At age 17 years (mean age = 16.9, SD = 0.1 years), 183 adolescents (65.6% of the invited) participated in the study. We used the shortened version of the Horne-Östberg morningness-eveningness Questionnaire to define the chronotype, and actigraphs to define the naturally occur circadian rhythm over a 4 to 17 days' period (mean nights N = 8.3, SD = 1.8). The Achenbach software was used to obtain T-score values for YSR psychiatric problem scales. The analyses were adjusted for important covariates including gender, socioeconomic status, body mass index, pubertal maturation, mother's licorice consumption during pregnancy, and actigraph-defined sleep duration and quality. Eveningness was associated with higher scores in rule-breaking behavior and conduct problems (as assessed either by midpoint of sleep or by self-reported chronotype, p-values <0.05), attention deficit/hyperactivity problems (by self-reported chronotype, p-values <0.05), with affective problems (by midpoint of sleep and by self-reported chronotype, p-values <0.05) and somatic complaints (by self-reported chronotype, p-values <0.05), as compared to circadian tendency toward morningness. Our results suggest that the association between eveningness and externalizing problem behavior, present in children and younger adolescents, is also present in late adolescence when circadian rhythms shift toward evening.

Chronotype is an emerging predictor of health and longevity, and understanding its influence on chronic diseases is important for constructing conceptual models of long-term pathways to health. We assessed the associations of chronotype with health status in the general Finnish adult population. Our population-based data were derived from the National FINRISK 2012 study and consisted of 4414 participants, aged 25-74 years, living in Finland. As part of their health examination, participants were asked about their circadian preference to the daily activities (morningness-eveningness) and a diagnosis or treatment for a set of common noncommunicable medical conditions and chronic diseases during the past 12 months. We found that there were 1935 (43.8%) morning types (MTs) and 595 (13.5%) evening types (ETs) and that 1884 (42.7%) were intermediates. As compared with the MTs, the ETs had significantly greater odds for depression (OR = 2.44, 95% CI = 1.52-3.90, p < 0.001) and other mental disorders (OR = 5.18, 95% CI = 2.32-11.52, p < 0.001). The odds were also increased for gallstones, and chronic obstructive pulmonary disease, but these did not remain significant after controlling for multiple testing. Responses to the single-item subjective estimation on the chronotype yielded the association of the definitely evening type of persons with the diagnosis or treatment of cardiac insufficiency (OR = 1.99, 95% CI = 1.02-3.88, p = 0.044) that was corroborated as the greater the eveningness score was, the more common the diagnosis or treatment of cardiac insufficiency was (β = 0.92, 95% CI = 0.85-0.98, p = 0.013). This exploratory study adds further support to the role of evening chronotype in chronic disease risk, albeit underlying mechanisms remain to be elucidated.

Sleep problems during pregnancy impair maternal health and increase the risk for adverse pregnancy outcome. The circadian preference toward eveningness has been associated with sleep problems in previous studies. Here, we studied whether evening-type women had more sleep problems during their pregnancy, as compared with other chronotypes, in a sample consisting of 1653 pregnant women from the Finnish CHILD-SLEEP Birth Cohort. Chronotype was assessed with a shortened version of the morningness-eveningness questionnaire. Pregnant evening-type women reported more sleep problems, including troubles of falling asleep (OR = 3.4, p < 0.0001), poor sleep quality (OR = 2.9, p < 0.01) and daily tiredness (OR = 3.2, p < 0.0001) than the morning-type women, even after controlling for sleep duration and sleep deprivation. They had higher scores on Epworth Sleepiness Scale (p < 0.05), Basic Nordic Sleep Questionnaire (p < 0.0001) and Global Seasonality Score (p < 0.01) and were also more often smokers, also during pregnancy (p < 0.001) and reported poorer general health (p < 0.001) than the morning-type women. They also reported having had more sleep problems during their childhood (OR = 1.5, p < 0.05) and adolescence (OR = 2.0, p < 0.001) than the morning-type women. Our results indicate that eveningness is associated with more sleep problems and unhealthy life habits during pregnancy.

Sleep problems, especially nightmares and insomnia, often accompany depression. This study investigated how nightmares, symptoms of insomnia, chronotype and sleep duration associate with seasonal affective disorder, a special form of depression. Additionally, it was noted how latitude, a proxy for photoperiod, and characteristics of the place of residence affect the prevalence of seasonal affective disorder and sleep problems. To study these questions, data from FINRISK 2012 study were used. FINRISK 2012 consists of a random population sample of Finnish adults aged 25-74 years (n = 4905) collected during winter from Finnish urban and rural areas spanning the latitudes of 60°N to 66°N. The Seasonal Pattern Assessment Questionnaire was used to assess symptoms of seasonal affective disorder. Participants with symptoms of seasonal affective disorder had significantly increased odds of experiencing frequent nightmares and symptoms of insomnia, and they were more often evening chronotypes. Associations between latitude, population size and urbanicity with seasonal affective disorder symptoms and sleep disturbances were generally not significant, although participants living in areas bordering urban centres had less sleep problems than participants from other regions. These data show that the prevalence of seasonal affective disorder was not affected by latitude., (© 2016 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.)

A cross-sectional population-based survey, the National FINRISK 2012 Study, designed to monitor chronic diseases and their risk factors in Finland. A random sample of 10,000 adults aged 25-74 years, and of them, 64% (n=6424) participated the study. Participants subjectively reported the total durations for sleep and naps (n=6238), sleep quality (n=5878), bedtimes and wake-up times separately for working days and weekends yielding the amount of sleep debt (n=5878), and the seasonal variation in sleep duration (n=4852). The participants were asked whether they were diagnosed or treated for common chronic diseases in the past 12 months. Logistic regression models were adopted to analysis and adjusted for a range of covariates as potential confounding factors. Total sleep duration and nap duration prolonged in depression and other mental disorder (p<.001 for all). Seasonal variation in sleep duration was associated with depression (p=.014), hypertension (p=.018) and angina pectoris (p=.024). Participants with gallstones, cardiac insufficiency, depression, or degenerative arthritis had poor sleep quality (odds ratios of 1.6-6.3, p=.001 or less for each). Those with degenerative arthritis had sleep debt less (p<.05) and those with angina pectoris more (p<.05) than individuals without these medical conditions. Depression is significantly associated with sleep problems, albeit no sleep debt. Cardiovascular diseases, degenerative arthritis, and gallstones had significant associations with one or more sleep problems. There is therefore a need for more successful management of sleep problems in chronic diseases to improve the quality of life, to reduce treatment relapses, and to increase health and longevity in a population.

The purpose of this study was to assess how seasonality is associated with some of the most common non-communicable diseases (NCDs) in the general Finnish population. The global seasonality score (GSS) was used to measure the magnitude of seasonality in 4689 participants, in addition to which they reported the extent to which the seasonal variations in mood and behavior were experienced as a problem. Regression models and the odds ratios were adopted to analyze the associations adjusted for a range of covariates. Seventy percent of the participants had seasonal variations in sleep duration, social activity, mood, or energy level, and forty percent those in weight and appetite. Angina pectoris and depression were significantly associated with seasonality throughout the analysis. Hypertension, high cholesterol levels, diabetes, other (than rheumatoid) joint diseases and other (than depressive) psychological illnesses were significantly associated with experiencing a problem due to the seasonal variations, with an increase in the GSS, and with seasonal affective disorder and its subsyndromal form. The co-occurrence of the seasonal variations in mood and behavior with certain common NCDs warrants future research to have insights into the etiology and potentially shared pathways and mechanisms of action., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Aims: Diurnal preference towards eveningness among adults has been associated with unhealthy habits and a range of health hazards, such as sleeping problems and higher odds for depression. We wanted to analyse whether diurnal preference towards eveningness is associated with more severe symptoms regarding sleep problems and mental disorders among young adults., Methods: Our sample consists of 469 young adults, aged 18-29 years, from the Mental Health in Early Adulthood Study in Finland (MEAF) conducted in 2003-2005. Chronotype was based on the assessment of one question that was asked first in 2000-2001 and the second time in 2003-2005. Those 73 participants who changed their chronotype were excluded from the main analysis, but separate analyses were performed with this group., Results: Concerning sleep, E-types reported higher dependency on alarm clocks (p < 0.001), and E-types and I-types had more problems in feeling refreshed after waking up (p < 0.0001 and p < 0.05 respectively) than M-types. Regarding mental health, E-types and I-types had lower odds for any lifetime DSM-IV Axis I disorder (p < 0.05 and p < 0.01 respectively) than M-types., Conclusions: Our results are in line with previous findings that those with the diurnal preference towards eveningness have more frequently three or more lifetime mental disorders, more sleeping problems, more seasonal variation in mood and behaviour, and more burnout compared with those with the diurnal preference towards morningness.

Background: Preference to time the daily activities towards the evening hours has been associated with a greater likelihood for depression in earlier studies consisting of relatively small samples., Methods: In the current study, we analyzed the relationship between chronotype and depression using a combined population-based sample of 10,503 Finnish adults aged 25 to 74 years from the two national FINRISK 2007 and 2012 health examination studies., Results: Our results confirmed that eveningness was significantly associated with the increased odds for a diagnosed depressive disorder, antidepressant medication, and depressive symptoms (p<0.0001 for each), after controlling for a range of depression-attributed and potential confounding factors. Regardless of depressive symptoms, Evening-types had lower systolic and diastolic blood pressures, a smaller waist circumference, and a lower body weight than other chronotypes., Limitations: A limitation to our study is that the assessment of chronotype and information about depression was based on the self-report information only. However, the big population-based sample, which is derived from a national health examination survey, is a major strength of our study., Conclusions: In conclusion, our study is in line the results from the previous, smaller sample size studies confirming that Evening-types have higher risk for depression than other chronotypes. This risk is elevated even among those Evening-types with sufficient amount of sleep., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Earlier studies have revealed that the more the preference to schedule daily activities towards the evening hours is, the higher the odds for a range of health hazards are. Therefore, we wanted to analyze, whether the behavioral trait of morningness-eveningness is associated with articular and spinal diseases or those with musculoskeletal disorders. Participants (n = 6089), as part of the National FINRISK 2007 Study, were derived from the general population, aged 25 to 74 years, living in Finland. Chronotype was assessed based on six items from the original Horne-Östberg Morningness-Eveningness Questionnaire. Information about risk factors and the diagnoses of articular and spinal diseases were based on the self-reported information. Our results suggest that Evening-types have higher odds for articular and spinal diseases as compared with Morning-types, and this risk is heightened especially regarding spinal disease and backache (odds ratios of 1.8 to 2.1, and 1.6 to 1.8, respectively) and remains significant after controlling for the sex, age, education, civil status, physical activity, alcohol use, and smoking, and additionally for the body-mass index, insufficient sleep, or depressive symptoms.

Most theories of the evolution of virulence concentrate on obligatory host-pathogen relationship. Yet, many pathogens replicate in the environment outside-host where they compete with non-pathogenic forms. Thus, replication and competition in the outside-host environment may have profound influence on the evolution of virulence and disease dynamics. These environmentally growing opportunistic pathogens are also a logical step towards obligatory pathogenicity. Efficient treatment methods against these diseases, such as columnaris disease in fishes, are lacking because of their opportunist nature. We present a novel epidemiological model in which replication and competition in the outside-host environment influences the invasion ability of a novel pathogen. We also analyze the long-term host-pathogen dynamics. Model parameterization is based on the columnaris disease, a bacterial fresh water fish disease that causes major losses in fish farms worldwide. Our model demonstrates that strong competition in the outside-host environment can prevent the invasion of a new environmentally growing opportunist pathogen and long-term disease outbreaks.

Earlier studies have found associations of chronotypes with a range of health-related factors. In the light of these findings, the behavioral trait of eveningness in particular associates with determinants that might have a negative impact on health. In this study, based on a random sample of population aged 25-74 years living in five large geographical areas in Finland (N = 6089), we tested whether the evening chronotypes have the increased odds for respiratory symptoms and diseases. As a result, after controlling for socio-demographic and lifestyle factors, evening-types had wheezy breathing without respiratory infection, a diagnosed or treated bronchial asthma, awoken in shortness of breath, awoken in heavy to breath, wheezy breathing with dyspnea, wheezy breathing as such and medication for asthma more often than morning-types (odds ratios (ORs) of 1.5-1.9) and intermediate-types (ORs of 1.3-1.6). In addition, evening-types had current medication for asthma, and awoken in coughing more often (OR = 1.5 and OR = 1.4, respectively) than morning-types. Evening-types did not have a diagnosed or treated chronic bronchitis more frequently than others. Our results suggest that the behavioral trait of eveningness associates with the increased odds for the bronchial asthma and nocturnal asthma in particular.

Study Objectives: Our study explored if bedtimes influenced school performance and motivation, as well as the odds ratio (OR) for health-related concerns in adolescents., Methods: The School Health Promotion Study was based on an anonymous self-report questionnaire conducted in 90% of the municipalities in Finland. The study was conducted during 2008 and 2010 in Southern Finland, Eastern Finland, and Lapland, and during 2009 and 2011 in Western Finland, Northern Finland, and Åland. Several indicators were used to measure school performance and motivation. Accidents and health-related complaints, such as depressive symptoms, sleep quality, neck or shoulder pains, lower back pains, stomachaches, anxiety or nervousness, irritation or tantrums, headaches, and tiredness or dizziness were analyzed in relation to the usual bedtime. Our study had a relatively large sample size (N=384,076), consisting of students in the eighth and the ninth grades of secondary schools and the first and the second grades of upper secondary and vocational schools (ages 14-20 years) in Finland., Results: All of the various indicators used to assess school performance and motivation suggest that the later the bedtime of adolescents, the lower their school performance and their motivation. Similarly later bedtimes increase the OR for depressive symptoms and other negative health consequences in adolescents as well as a tendency towards accidents. All of these problems were emphasized in students with bedtimes of 11:30 PM and later., Conclusions: Late bedtimes, especially those after 11:30 PM, indicate poor sleep which deteriorates school performance and motivation and increases the OR for depressive symptoms and other health-related issues in adolescents., (Copyright © 2013 Elsevier B.V. All rights reserved.)

There is evidence for the reciprocal interaction between circadian oscillation and reproduction, and disruption of circadian rhythms has been associated with impaired menstrual functions and reduced fertility in women. However, only little information is available on the relationship between reproduction and chronotype. The aim of the present study is to better assess this relationship. The participants (aged 25 to 74 yrs) were selected randomly from the Finnish Population Information System. The data from 2672 female participants of the National FINRISK Survey 2007 were analyzed to test the associations between chronotype (morning, intermediate, or evening) and reproductive features. Of the participants, 139 (5.6%) were evening, 1217 (48.7%) intermediate, and 1145 (45.8%) morning chronotypes. Among the participants aged 25 to 54 yrs, the duration of menstrual cycle was longer among evening chronotypes (28.8 ± 4.4 d) than among morning (27.7 ± 2.6 d; p < 0.01) and intermediate (27.8 ± 3.3 d; p = 0.05) chronotypes. Significant correlations were found between the higher morningness-eveningness scores (the more of morning chronotype) and the shorter durations of menstrual bleeding, both in the whole sample (p < 0.001) and after limiting the analyses to women younger than 55 yrs (p < 0.05). In multivariable analyses on the whole sample, as compared with morning chronotypes, intermediate chronotypes had a significantly longer duration of menstrual bleeding (B = 0.160, 95% confidence interval [CI] = 0.044 to 0.276; p < 0.01) as well as a higher odds for difficulties in getting pregnant (odds ratio [OR] = 1.464, 95% CI = 1.118 to 1.917; p < 0.01). Our findings suggest that chronotype is related to the reproductive function in women.

Certain preferences for the timing of daily activities (chronotype) may predispose an individual to sleep problems and mood disorders. In this study, we have examined the link between chronotypes and depression. Participants (N = 6071) were recruited from a random sample of the general population aged 25 to 74 yrs living in defined geographical areas, as part of the National FINRISK Study in 2007 in Finland. Chronotype assessment was based on six items from the original Horne-Östberg Morningness-Eveningness Questionnaire. Depression was assessed with four self-reported items, including two probes for a diagnosis of a major depressive episode, diagnosed or treated depression, and use of antidepressants. We also analyzed correlations between chronotype and several health indicators, such as systolic and diastolic blood pressures, resting heart rate, weight, and waist circumference. The odds ratios for a range of indicators of depression were higher for evening types (2.7- to 4.1-fold) and intermediate types (1.5- to 1.9-fold) than for morning types. Our results suggest that individuals having a preference for evening hours to carry out their daily activities are prone to depression.

In this study, the authors analyzed whether chronotypes, sleep duration, and sleep sufficiency are associated with cardiovascular diseases and type 2 diabetes by using the National FINRISK Study 2007 data (N = 6258), being a representative sample of the population aged 25 to 74 living in five areas of Finland. Health status assessments and laboratory measurements from the participants (N = 4589) of the DILGOM substudy were used for the detailed analysis of chronotype. Evening types had a 2.5-fold odds ratio for type 2 diabetes (p < .01) as compared with morning types, the association being independent of sleep duration and sleep sufficiency. Evening types had a 1.3-fold odds ratio for arterial hypertension (p < .05 after controlling for sleep duration or sleep sufficiency), a faster resting heart rate and a lower systolic blood pressure (both p < .01), and lower levels of serum total cholesterol and low-density lipoprotein cholesterol (both p < .0001) than morning types. There were significant 1.2- to 1.4-fold odds ratios for arterial hypertension among those with long or short sleep durations or reduced sleep sufficiency. To conclude, the behavioral trait towards eveningness is suggested to predispose individuals to type 2 diabetes in particular, whereas compromised sleep is robustly associated with arterial hypertension.

Disrupted circadian rhythms may lead to failures in the control of the cell division cycle and the subsequent malignant cell growth. In order to understand the pathogenesis of cancer more in detail, it is crucial to identify those mechanisms of action which contribute to the loss of control of the cell division cycle. This mini-review focuses on the recent findings concerning the links between the human circadian clock and cancer. Clinical implications concern not only feasible methods for the assessment of the circadian time of an individual or for the determination of the best time for administration of a drug of treatment, but also in the future genetic tests for screening and for planning treatment.

Background: Seasonal variations in mood and behavior are common among the general population and may have a deteriorating effect on cognitive functions., Aims: In this study the effect of seasonal affective disorder (SAD-like symptoms) on cognitive test performance were evaluated in more detail., Methods: The data were derived from the study Mental Health in Early Adulthood in Finland. Participants (n = 481) filled in a modified Seasonal Pattern Assessment Questionnaire (SPAQ) and performed cognitive tests in verbal and visual skills, attention and general intelligence., Results: SAD-like symptoms, especially regarding the seasonal variations in weight and appetite, had a significant effect on working memory (Digit Span Backward, P = 0.008) and auditory attention and short-term memory (Digit Span Forward, P = 0.004). The seasonal variations in sleep duration and mood had an effect on auditory attention and short-term memory (Digit Span Forward, P = 0.02 and P = 0.0002, respectively). The seasonal variations in social activity and energy level had no effect., Conclusions: Seasonal changes in mood, appetite and weight have an impairing effect on auditory attention and processing speed. If performance tests are not to repeated in different seasons, attention needs to be given to the most appropriate season in which to test.

Individuals show variation in their preference for the daily timing of activities. In this study the authors analyzed whether chronotypes associate with sleep duration and sleep-related complaints. The authors used the National FINRISK Study 2007 Survey data on 3696 women and 3162 men, representative of the Finnish population aged 25 yrs and older, for the assessment of chronotype and self-reported sleep. Evening types experienced insomnia symptoms, had nightmares, and had used recently hypnotics significantly more often than other chronotypes among both men and women. In a multinominal logistic regression model predicting insufficient sleep, the association of eveningness with insufficient sleep was not abolished after adjustment for sex, age, and sleep duration. The prevalence of short sleepers was significantly higher in evening types among men than among women, whereas that of long sleepers was significantly higher in evening types among both men and women, as compared with the other chronotypes. These results indicate that eveningness predisposes individuals to a range of sleep complaints.

Opportunist saprotrophic pathogens differ from obligatory pathogens due to their capability in host-independent growth in environmental reservoirs. Thus, the outside-host environment potentially influences host-pathogen dynamics. Despite the socio-economical importance of these pathogens, theory on their dynamics is practically missing. We analyzed a novel epidemiological model that couples outside-host density-dependent growth to host-pathogen dynamics. Parameterization was based on columnaris disease, a major hazard in fresh water fish farms caused by saprotrophic Flavobacterium columnare. Stability analysis and numerical simulations revealed that the outside-host growth maintains high proportion of infected individuals, and under some conditions can drive host extinct. The model can show stable or cyclic dynamics, and the outside-host growth regulates the frequency and intensity of outbreaks. This result emerges because the density-dependence stabilizes dynamics. Our analysis demonstrates that coupling of outside-host growth and traditional host-pathogen dynamics has profound influence on disease prevalence and dynamics. This also has implications on the control of these diseases.

Evolution is a continuous process that changes population genetics towards greater adaptation. Sleep is an example of a conservative trait that appears everywhere and is regulated similarly in the animal kingdom. Because of this similarity in sleep regulation different animal models and genetic modification can be used in basic research and in studies of sleep related diseases. Recent research has enlightened the function of the clock genes and the synaptic plasticity during sleep, so that we can better understand the need for sleep and the effects of sleep loss. This knowledge is needed in order to prevent and treat sleep related diseases.

Intrauterine thymectomy was carried out on days 36, 40, 48 and 68 (neonatal) of foetal life to investigate the role of thymus and emigration of thymocytes in the development of mitogenic (PHA, Con A, DxS) responses in the guinea pig. The results provide further evidence that emigration of thymocytes is a continuous process which takes place already at the time of demarcation between thymic cortex and medulla (before day 36 of gestation) and again immediately after birth. In the lymph nodes of guinea pigs thymectomized on day 36 in utero a small PHA and Con A responding cell population exists at the time of birth but not any more 3-4 mth later. This population is considered to depend on the transplacental thymic product(s). However, spleen and blood lymphocytes of animals thymectomized on day 36 in utero respond to PHA and Con A to some extent at the age of 3-4 mth, suggesting that the population emigrating before day 36 has a longer survival in the spleen and blood than in lymph nodes. Thymectomy at 40 days of gestation leaves an additional population which can express a good PHA and Con A response even in lymph nodes without a direct thymic influence. Responses to DxS were not significantly affected by the intrauterine thymectomy. Thus, intrauterine thymectomy at 36 days of gestation induces a severe but not complete T cell depletion in the guinea pig.