Light is necessary for life, and artificial light improves visual performance and safety, but there is an increasing concern of the potential health and environmental impacts of light. Findings from ...a number of studies suggest that mistimed light exposure disrupts the circadian rhythm in humans, potentially causing further health impacts. However, a variety of methods has been applied in individual experimental studies of light-induced circadian impacts, including definition of light exposure and outcomes. Thus, a systematic review is needed to synthesize the results. In addition, a review of the scientific evidence on the impacts of light on circadian rhythm is needed for developing an evaluation method of light pollution, i.e., the negative impacts of artificial light, in life cycle assessment (LCA). The current LCA practice does not have a method to evaluate the light pollution, neither in terms of human health nor the ecological impacts. The systematic literature survey was conducted by searching for two concepts: light and circadian rhythm. The circadian rhythm was searched with additional terms of melatonin and rapid-eye-movement (REM) sleep. The literature search resulted to 128 articles which were subjected to a data collection and analysis. Melatonin secretion was studied in 122 articles and REM sleep in 13 articles. The reports on melatonin secretion were divided into studies with specific light exposure (101 reports), usually in a controlled laboratory environment, and studies of prevailing light conditions typical at home or work environments (21 studies). Studies were generally conducted on adults in their twenties or thirties, but only very few studies experimented on children and elderly adults. Surprisingly many studies were conducted with a small sample size: 39 out of 128 studies were conducted with 10 or less subjects. The quality criteria of studies for more profound synthesis were a minimum sample size of 20 subjects and providing details of the light exposure (spectrum or wavelength; illuminance, irradiance or photon density). This resulted to 13 qualified studies on melatonin and 2 studies on REM sleep. Further analysis of these 15 reports indicated that a two-hour exposure to blue light (460 nm) in the evening suppresses melatonin, the maximum melatonin-suppressing effect being achieved at the shortest wavelengths (424 nm, violet). The melatonin concentration recovered rather rapidly, within 15 min from cessation of the exposure, suggesting a short-term or simultaneous impact of light exposure on the melatonin secretion. Melatonin secretion and suppression were reduced with age, but the light-induced circadian phase advance was not impaired with age. Light exposure in the evening, at night and in the morning affected the circadian phase of melatonin levels. In addition, even the longest wavelengths (631 nm, red) and intermittent light exposures induced circadian resetting responses, and exposure to low light levels (5-10 lux) at night when sleeping with eyes closed induced a circadian response. The review enables further development of an evaluation method of light pollution in LCA regarding the light-induced impacts on human circadian system.
Short or long sleep duration, insufficient sleep, and Evening chronotype associate with many health issues and increased risk for mortality. Understanding population-level changes in sleep and ...chronotype frequencies is important for assessing the prospective health status of the society and future challenges on health care at a national level. This study examines the cross-sectional differences in sleep duration, insufficient sleep, and chronotype frequencies indicated by both circadian preference and habitual sleep-wake rhythm among adults living in Finland during a 10-year period of 2007–2017.
The study sample (N = 18 039) was derived from he National FINRISK 2007 and 2012 Studies, and The FinHealth 2017 Study, each consisting of a random sample of adults, aged 25–74 years and as stratified by age and sex, and providing the self-reported data on their circadian preference, habitual daily sleep duration, insufficient sleep and bedtimes.T
During the 10 years, sleep duration decreased, insufficient sleep increased and circadian preference towards eveningness increased significantly in each 10-year age group and among both sexes. In general, eveningness was more common among younger adults in all the study years but, as compared to 2012, in 2017 bedtimes and midpoint of sleep were more advanced among this age group while sleep-wake rhythm became more delayed in older adults. The decrease in sleep duration and the increase in insufficient sleep were emphasized in younger adults and especially in women, whereas the increase in eveningness in older adults and in men.
The evolution of sleep and chronotype frequencies from 2007 to 2017 is alarming, as these might lead to a poorer health status in the adult population and thus cause more strain to the public health. The mismatch between sleep-wake behavior and circadian preference was emphasized in young adults, indicating a greater risk for circadian misalignment in the Finnish adult population in the future, if there will not be any interventions to correct this mismatch.
•Insufficient sleep has become more common among adults, especially in women.•Sleep duration has decreased in every age group from 25 to 74 years old adults.•Eveningness has increased in every age group from 25 to 74 years old adults.•Shorter sleep duration in 2017 than in 2007 was apparent both in men and women.•Higher frequency of eveningness in 2017 than in 2007 was apparent in both sexes.
Circadian clocks have evolved a slowing-down mechanism. Temperature may be the original and universal time-giver to the organism. Brown adipose tissue generates heat and guides the circadian rhythm ...of core body temperature. The cryptochrome proteins regulate the temperature entrainability, and their dysfunction may let the activation of brown adipose tissue affect the brain more easily. Therefore, the activity of brown adipose tissue may compromise the slowing-down mechanism and thereby contribute to the emergence of mood disorders and the increase in suicide mortality around the time of puberty.
Individuals with a later preference for the daily activities (evening types) tend to have unhealthier behaviors, which could increase their risk for obesity when compared those with an earlier ...preference (morning types). Furthermore, later food intake timing, another behavior more characteristic of evening types, has been associated with obesity. However, chronotype differences in the long-term weight change and the role of chronotype in the association between energy intake timing and obesity risk are not clear. To study this we first examined the independent associations of chronotype and energy intake timing with anthropometric changes and then whether chronotype modified the association between energy intake timing and obesity risk. Our data included 1097 Finns from DILGOM (DIetary Lifestyle and Genetic Determinants of Obesity and Metabolic syndrome) 2007 (baseline) and 2014 (follow-up) and from Findiet 2007. Chronotype was assessed with a shortened version of Horne and Östberg's morningness-eveningness questionnaire. Energy intake timing (as percentages of the total energy intake in the morning/evening) was assessed with 48-h dietary recalls. Weight, body mass index (BMI), and waist circumference were based on measured and self-reported values. Analysis of co-variance and multivariable logistic regression models were used for statistical analyses. Evening typed women had greater weight gain (+ 2.3 kg vs. + 0.3 kg, P = 0.016) and increase in BMI (0.7 kg/m
vs. -0.1 kg/m
, P = 0.024) than morning typed women. After excluding participants with depression, these associations attenuated to non-significant. Compared to participants whose energy intake was proportionally lowest during evening, those with proportionally highest energy intake during evening were more likely with obesity (BMI≥ 30 kg/m
) after follow-up (OR 1.97, 95% CI 1.21-3.21, Ptrend = 0.042). Participants' chronotype did not modify this association (Pinteract = 0.95). In conclusion, our findings indicated that evening energy intake may play a role in obesity regardless of the chronotype. Furthermore, evening typed women were more prone to increases in their anthropometrics, which seem to be at least partly explained by depression. Further studies of this topic are warranted.
Individuals with a later chronotype (evening types) tend to have unhealthier behaviors and increased morbidity and mortality as compared with those with an earlier chronotype (morning types). ...However, the role of genetics in explaining evening types’ adverse health and health behavior is unclear. Our aim was to study genetic associations of chronotype among 8433 Finns from the cross-sectional National FINRISK 2007 and 2012 studies. First, we studied associations between chronotype and 20 key clock genes with a candidate-gene approach and then performed a full genome-wide association study (GWAS) of chronotype. We also developed a genetic risk score (GRS) for chronotype based on 313 single nucleotide polymorphisms (SNPs) that have previously been associated with chronotype. Chronotype was assessed with a shortened version of Horne and Östberg’s Morningness-Eveningness Questionnaire (sMEQ), and for comparison, we also used the single self-evaluation question on chronotype from the questionnaire. Linear and logistic regression was used for statistical analysis assuming additive effects. The clock gene analysis revealed 1 independent association signal within NR1D2 (lead SNP rs4131403) that was associated with chronotype (p < 0.05; as based on both chronotype assessment methods). The GWAS analysis did not yield any genome-wide significant associations (p > 5 × 10−8). However, higher GRS was associated with evening chronotype (p < 0.001; as based on both chronotype assessment methods). In conclusion, our findings indicated novel genetic associations between chronotype and the NR1D2 clock gene, which has previously been associated with carbohydrate and lipid metabolism. Furthermore, the GRS was able to capture the genetic aspect of chronotype in our study population. These findings expand our knowledge of the genetic basis of chronotype.
Objective
To examine the association between chronotype and timing of energy and macronutrient intakes in adults.
Methods
The study sample included 1,854 participants from the National FINRISK 2007 ...and FINDIET 2007 studies, aged 25 to 74 years. Diet was assessed with 48‐hour dietary recalls. Chronotype was assessed with a shortened version of Horne and Östberg's Morningness–eveningness Questionnaire. Associations between chronotype and intakes of energy and macronutrients in the morning (by 10 am) and in the evening (after 8 pm) were analyzed with linear regression and ANOVA followed by Bonferroni post hoc test.
Results
In the morning, evening types had lower energy and macronutrient intakes (except for sucrose of which they had a higher intake) than morning types (P < 0.05), while in the evening, evening types had higher intakes of energy, sucrose, fat, and saturated fatty acids than morning types (P < 0.05). On the weekend, chronotype differences in evening intakes of energy, sucrose, and fat intake were more pronounced, and evening types had more eating occasions and more irregular meal times than morning types.
Conclusions
Postponed energy and macronutrient intake timing of evening types with unfavorable dietary patterns may put them at higher risk of obesity and metabolic disturbances in the future.
Objective: The aim is to report the outcomes of the suicide prevention training in terms of the self-perceived impact on the participants.
Design: The three-hour training consisted areas of risk and ...protective factors, screening and evaluating suicide risk, raising concerns and confronting suicidal patients, and treating suicidal ideation in primary healthcare and the associated referral processes.
Subjects: The studied participants consisted of general practitioners, nurses, public health nurses and social work professionals.
Main outcome measures: Participants assessed their own competence on online form regarding four training areas prior to and two weeks after the training.
Results: The response rate was 25%. The self-perceived competence of the healthcare professionals increased in all training areas and in all occupational groups. The healthcare professionals' competence regarding the risk and protective factors training area saw the greatest increase across all professional groups except nurses. There were, however, differences between the groups.
Conclusion: Suicide prevention training for primary healthcare professionals did increase the self-perceived competence of the participants in all areas covered by the training. Regular follow-up training is required in order for these improvements to be further developed and retained.
Key points
After the suicide prevention training all participants self-perceived increase in their competence in all training areas.
The GPs self-perceived most increase in risk and protective factors and nurses in raising concerns and confronting suicidal patients.
The GPs' lowest increase was in the area of treating suicidal ideation in primary health care and the referral processes.
Problems with sleep appear a key feature in psychological distress emerging as suicidal thoughts at its worst. As part of a nationwide health examination study on 4387 participants, aged 18–97 years, ...we analyzed, whether suicidal thoughts during the past 7 days as scored on the Hopkins Symptom Checklist were associated with current sleep disturbances including difficulties in falling or staying asleep, daytime tiredness, loss of sleep over worry, insufficient sleep, and the usage of sleeping pills. In the stepwise regression analysis of the recent suicidal thoughts, the current daytime tiredness showed the significant association most robustly, whereas by adding clinically relevant information to analysis, the current difficulties falling or staying asleep, the use of mental health services during the past 12 months, and the level of education predicted the recent suicidal thoughts significantly. To conclude, recent suicidal thoughts were significantly associated with current sleep disturbances.
•Recent suicidal thoughts were significantly associated with current insomnia.•Current daytime tiredness associated most robustly with recent suicidal thoughts.•Self-report of sleep carries information on suicidal thoughts.
Abstract The individual variation in the circadian rhythms at the physiological level is not well understood. Albeit self-reported circadian preference profiles have been consolidated, their premises ...are grounded on human experience, not on physiology. We used data-driven, unsupervised time series modelling to characterize distinct profiles of the circadian rhythm measured from skin surface temperature in free-living conditions. We demonstrate the existence of three distinct clusters of individuals which differed in their circadian temperature profiles. The cluster with the highest temperature amplitude and the lowest midline estimating statistic of rhythm, or rhythm-adjusted mean, had the most regular and early-timed sleep–wake rhythm, and was the least probable for those with a concurrent delayed sleep phase, or eveningness chronotype. While the clusters associated with the observed sleep and circadian preference patterns, the entirely unsupervised modelling of physiological data provides a novel basis for modelling and understanding the human circadian functions in free-living conditions.
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