Seasonal vegetative and affective symptoms in the Finnish general population: testing the dual vulnerability and latitude effect hypotheses

Winter-time solar radiation, precipitation, and psychotropic medication purchases: A cohort study in Finnish public sector employees

Background

In Northern latitudes, winter is the darkest time of the year, and depressive episodes during winter are prevalent. Although changing weather patterns due to climate change are projected to result in warmer and wetter and, thus, even darker winters, research on the impact of winter-time natural light and precipitation on mental health is scarce. We examined associations of exposure to solar radiation and precipitation with psychotropic medication and antidepressant purchases in winter months.

Methods

Of the 251,268 eligible participants from the Finnish public sector study, aged ≥18 years, 72% were women. Associations for municipality-level 4-week average solar radiation and precipitation with register-based medication purchases from 1999 to 2016 were analyzed using random effects method with Poisson regression. A 6-month washout period with no purchases was applied to each purchase. Confounding by region and year, and effect modifications by sex, age, and socioeconomic status were examined.

Results

No association was observed for an increase in 4-week average of solar radiation by standard deviation (585 kJ/m2) with any psychotropic medications (incidence rate ratio: 0.99; 95% confidence interval: 0.98, 1.00) or antidepressants (1.00; 0.99, 1.01). No difference in any psychotropic medication or antidepressant purchases in participants exposed to high solar radiation (≥2000 kJ/m2) compared with those with the lowest exposure (<500 kJ/m2) was observed. No associations were observed for precipitation.

Conclusion

No evidence linking higher solar radiation exposure to reduced psychotropic medication purchases, nor higher precipitation exposure to increased medication purchases in winter was observed. Further research is needed to validate and expand upon these findings.

Seasonal variations in the mental state and heart rate variability in adolescents residing beyond the Arctic Circle

Background — Residence beyond the Arctic Circle is associated with a distinct condition, Polar Tension Syndrome (PTS), which shares similarities with Seasonal Affective Disorder (SAD). However, the interplay of mental state and heart rate variability within the context of seasonal photoperiodicity in both PTS and SAD remains poorly understood. Objectives — This study investigated the effects of polar photoperiodicity on the mental and physiological states of male adolescents living in the Kola Peninsula, Russia (67°34′ N, 33°23′ E), a region beyond the Arctic Circle. Methods — Mental state was assessed using the State-Trait Anxiety Inventory (STAI) and the Self-Esteem of health, Activity, and Mood (SAM) scales. Heart rate variability (HRV) indices provided objective measures of the psychophysiological state. Results — Significant associations were found between state and trait anxiety (StA and TrA) and seasonal photoperiodicity in adolescents residing beyond the Arctic Circle. Reduced parasympathetic (HF) and increased sympathetic (LF) Autonomic Nervous System (ANS) contributions to heart rate (HR) regulation during the polar night may underlie the physiological manifestations of polar tension syndrome (PTS) and seasonal sffective disorder (SAD), both characterized by elevated anxiety. Analysis revealed monthly fluctuations in the dominance of HF and LF contributions to HR regulation, with LF predominating during the polar night and in March. Conclusion — This study demonstrates an association between state and trait anxiety (StA and TrA), heart rate regulation, and seasonal photoperiodicity in adolescents residing beyond the Arctic Circle. Adolescents with anxiety and low parasympathetic (HF) HRV activity show an increased risk of developing PTS and SAD symptoms.

Research status, hotspots, and implications of seasonal affective disorder: A bibliometric analysis based on CiteSpace and VOSviewer

The objective was to determine the research status and hotspots of seasonal affective disorders (SAD) based on bibliometric tools, which will contribute to the further research in this field. We used bibliometric tools CiteSpace and VOSviewer to conduct visual quantitative analysis on 465 SAD literatures in the Web of Science core database from 2008 to 2023 from multiple perspectives such as collaboration network, keywords, and literature citations. At the same time, we used Microsoft Word to make relevant tables. The publication of SAD-related literature has been on the rise in the past 15 years, countries with high production of SAD literature are mainly concentrated in the United States, Austria, and Canada, and certain cooperative relationships have been established between various institutions and scholars. Research keywords in our study are mainly limited to pathogenesis ("Photoperiod," "exposure," "winter," "serotonin transporter," and "creb") and treatment measures ("light therapy" and "melatonin"). In recent years, literature research hotspots mainly focus on the treatment of SAD with light therapy, the application of exogenous drugs, the biological clock mechanism of SAD pathogenesis, the relationship between SAD and inflammation, etc. The correlation between SAD and sleepiness and alternative treatments to light therapy may be future research hotspots. The research results reveal the future research focus of SAD. There is a considerable interest in the photoperiodic pathogenesis of SAD, light therapy and its alternative therapies, and there is still hope for further exploration. Substantial research into evidence-based prevention as well as treatment strategies is necessary to improve outcomes.

Well-being in healthy Icelandic women varies with extreme seasonality in ambient light

Seasonal variation in photoperiod may affect psychosocial and physical well-being in healthy persons. We tested this hypothesis in healthy pre-menopausal women, without a history of mood disorders, living year-round in Reykjavik, Iceland (64.1°N). Participants reported daily self-assessments of well-being throughout a complete ovulatory menstrual cycle in summer and/or winter (70% participated in both seasons). Scores for mood, cognitive acuity, social support, physical health and a composite of these four indicators were each significantly higher in summer than in winter (linear mixed effects models: p < .001 for each model); tiredness did not differ by season. The effect of season was not significantly changed by inclusion of body mass index and/or age as covariates. Some prior studies have been hampered by sparse time sampling, inattention to covariates and/or relying on recalled data. This is to our knowledge the first investigation to test the study hypothesis with daily real-time data spanning complete ovulatory menstrual cycles in each of two seasons. This dense sampling has revealed modest seasonal variation in well-being in healthy women. Daylength (sunlight exposure) is likely a major, but not necessarily sole, factor in these seasonal differences in well-being; temperature is likely less important given Iceland's relatively moderate (for its high latitude) seasonal temperature swings.

Synodic lunar phases and suicide: based on 2605 suicides over 23 years, a full moon peak is apparent in premenopausal women from northern Finland

Suicide data for this study were available for the period of March 1988 to June 2011, and involved 2111 male and 494 female victims from the Finnish province of Oulu. Data for lunar phases during that period were categorised into three groups: new moon (<25% visible), full moon (>75% visible) and other times with values in between. Seasonal effects were controlled with definitions for winter (Nov, Dec, Jan), spring (Feb, Mar, Apr), summer (May, June, July), and autumn (Aug, Sep, Oct). Suicide occurrences during different lunar phases were compared with their expected distribution using multinomial tests with all tests being two-tailed. Statistical significance was set at p < 0.05. No correlation between suicides and moon phase in any of the four seasons was apparent for male victims, but in winter for women it was (p = 0.001). Further analysis of the data revealed that the full moon association was statistically significant only for premenopausal women, defined as female victims younger than 45 years of age. To explain this unexpected finding a number of factors were considered, e.g., the darkness of a northern Finnish winter with increases of SAD and depression especially in premenopausal women, the influence of the lunar periodicity on the menstrual cycle, and cosmogeophysical effects on the humoral and autonomous nervous system.

Association between the Arylalkylamine N-Acetyltransferase (AANAT) Gene and Seasonality in Patients with Bipolar Disorder

OBJECTIVE

Bipolar disorder (BD) is complex genetic disorder. Therefore, approaches using clinical phenotypes such as biological rhythm disruption could be an alternative. In this study, we explored the relationship between melatonin pathway genes with circadian and seasonal rhythms of BD.

METHODS

We recruited clinically stable patients with BD (n=324). We measured the seasonal variation of mood and behavior (seasonality), and circadian preference, on a lifetime basis. We analyzed 34 variants in four genes (MTNR1a, MTNR1b, AANAT, ASMT) involved in the melatonin pathway.

RESULTS

Four variants were nominally associated with seasonality and circadian preference. After multiple test corrections, the rs116879618 in AANAT remained significantly associated with seasonality (corrected p=0.0151). When analyzing additional variants of AANAT through imputation, the rs117849139, rs77121614 and rs28936679 (corrected p=0.0086, 0.0154, and 0.0092) also showed a significant association with seasonality.

CONCLUSION

This is the first study reporting the relationship between variants of AANAT and seasonality in patients with BD. Since AANAT controls the level of melatonin production in accordance with light and darkness, this study suggests that melatonin may be involved in the pathogenesis of BD, which frequently shows a seasonality of behaviors and symptom manifestations.

Self-reported seasonality is strongly associated with chronotype and weakly associated with latitude

The aim of this study was to investigate the association between self-reported seasonality, i.e., seasonal variations in mood and related behavior, and chronotype, and between self-reported seasonality and home address' latitude. Data were collected from an online questionnaire with 45,338 participants. Seasonality and chronotype were measured with the Global Seasonality Score (GSS) and the Composite Scale of Morningness, respectively. The participants were categorized into extreme morning types, moderate morning types, intermediate types, moderate evening types, and extreme evening types. Furthermore, participants were categorized depending on home address' latitude. Data were analyzed with chi-square tests and logistic regression analyses adjusting for sex, age, marital status, level of education, and children living at home. Results showed that high seasonality (GSS 11+) was found in 20.9%. The prevalence dose-dependency ranged from 12.2% in extreme morning types to 42.6% in extreme evening types (adjusted OR = 4.21, CI = 3.27-5.41). The prevalence was higher in participants living in North-Norway (latitude from 65 to 71⁰N) versus South-Norway (latitude from 58 to 65⁰N) (23.8% versus 20.7%; adjusted OR = 1.18, CI = 1.08-1.28). When comparing the northernmost (69-71⁰N) to the southernmost (58-59⁰N) counties of Norway, the association was stronger (24.9% versus 18.7%; adjusted OR = 1.37, CI = 1.20-1.56). Among the adjusting variables, high seasonality was associated with female sex, younger age, being unmarried, low level of education, and not having children living at home. In conclusion, about one in five Norwegians reported high seasonality. High seasonality was strongly associated with late chronotype (being an evening type) and weakly associated with living in the north (high latitude).

Assessing impairment using a configural measure

Assessing impairment in daily functioning is an important part of a mental health evaluation and of monitoring progress in treatment. The Seasonality Assessment Form includes five yes/no impairment items written to reflect the ways that patients intuitively describe their levels of impairment. However, the items are not mutually exclusive and are not summative so that impairment severity is represented by the configural pattern of responses. This article used configural and graphical methods to examine the nature of response patterns and how to use them to generate an impairment severity score.

Low Daytime Light Intensity Disrupts Male Copulatory Behavior, and Upregulates Medial Preoptic Area Steroid Hormone and Dopamine Receptor Expression, in a Diurnal Rodent Model of Seasonal Affective Disorder

Seasonal affective disorder (SAD) involves a number of psychological and behavioral impairments that emerge during the low daytime light intensity associated with winter, but which remit during the high daytime light intensity associated with summer. One symptom frequently reported by SAD patients is reduced sexual interest and activity, but the endocrine and neural bases of this particular impairment during low daylight intensity is unknown. Using a diurnal laboratory rodent, the Nile grass rat (Arvicanthis niloticus), we determined how chronic housing under a 12:12 h day/night cycle involving dim low-intensity daylight (50 lux) or bright high-intensity daylight (1,000 lux) affects males’ copulatory behavior, reproductive organ weight, and circulating testosterone. We also examined the expression of mRNAs for the aromatase enzyme, estrogen receptor 1 (ESR1), and androgen receptor (AR) in the medial preoptic area (mPOA; brain site involved in the sensory and hormonal control of copulation), and mRNAs for the dopamine (DA) D1 and D2 receptors in both the mPOA and nucleus accumbens (NAC; brain site involved in stimulus salience and motivation to respond to reward). Compared to male grass rats housed in high-intensity daylight, males in low-intensity daylight displayed fewer mounts and intromissions when interacting with females, but the groups did not differ in their testes or seminal vesicle weights, or in their circulating levels of testosterone. Males in low-intensity daylight unexpectedly had higher ESR1, AR and D1 receptor mRNA in the mPOA, but did not differ from high-intensity daylight males in D1 or D2 mRNA expression in the NAC. Reminiscent of humans with SAD, dim winter-like daylight intensity impairs aspects of sexual behavior in a male diurnal rodent. This effect is not due to reduced circulating testosterone and is associated with upregulation of mPOA steroid and DA receptors that may help maintain some sexual motivation and behavior under winter-like lighting conditions.

No evidence of seasonal variation in mild forms of depression

BACKGROUND AND OBJECTIVES

Seasonal Affective Disorder (SAD) is ubiquitous in popular culture and has influenced psychiatric diagnosis with the inclusion of the seasonal pattern modifier for the Major Depressive Episode in DSM. However, recent research has not supported the association of Major Depressive Episode with seasonal changes. The present study was conducted to determine if a seasonally-related pattern of occurrence of mild variants of depression could be demonstrated in a population-based study.

METHODS

This is a cross-sectional U.S. survey of adults who completed the PHQ-8 Depression Scale with mild depression defined using a PHQ-8 cut score and a second model based on the DSM-5 diagnosis, Depression with insufficient symptoms. Regression models were used to determine if either variant of mild depression was related to season, latitude, or measures of daylight hours.

RESULTS

Neither measure of mild depression was related to daylight hours or its proxy measures.

LIMITATIONS

Screening instruments for depression, even if consistent with DSM-5 diagnostic criteria, do not allow a formal diagnosis of depression or the exclusion of similar-appearing disorders. Current depression symptoms but not duration of depressive episode is measured.

CONCLUSIONS

Mild depression is not related to seasonal changes or proxy measures of light exposure. The findings cast doubt on light deficiency as a causal factor of depressive disorders, which underpins the inclusion of the seasonal pattern modifier in DSM-5 and light supplementation as a treatment modality.

Tanning dependence and seasonal affective disorder are frequent among sunbathers but are not associated

Ultraviolet radiation (UVR) is a known risk factor for skin cancers. Those who are tanning dependent seek out UVR exposure. Many tanners have expressed symptoms of seasonal affective disorder (SAD), but conclusive evidence of a connection with tanning dependence is lacking. We evaluated the frequency of tanning dependence or abuse and symptoms of SAD among Finnish sunbathers and analysed whether phenomena are associated which could indicate a common biological mechanism. Sunbathing related tanning dependence/abuse among Finnish sunbathers were assessed using the Structured Interview for Tanning Abuse and Dependence measure (SITAD), and symptoms of SAD were assessed with the Seasonal Pattern Assessment Questionnaire (SPAQ). Of 229 sunbathers, 8% (n = 18) were classified as tanning-dependent, and 26% (n = 59) were classified as tanning abusers. Additionally, 16% (n = 37) met the criteria for SAD, and 26% (n = 60) met the criteria for subsyndromal seasonal affective disorder (S-SAD), but there was no significant association between tanning dependence or abuse and SAD or S-SAD. Sunbathing dependence or abuse and SAD/S-SAD were frequent among sunbathers, and they may promote sun-seeking risk behaviour. However, within this sample, tanning dependence and SAD/S-SAD were not associated.

Depression subtyping based on evolutionary psychiatry: Proximate mechanisms and ultimate functions

Major depressive disorder constitutes one of the leading causes of disability worldwide. However, it is not a unitary disease-it is a heterogeneous syndrome, with patients differing remarkably in symptom profile, pathophysiology and treatment responsiveness. Previous attempts to subtype major depressive disorder have showed limited clinical applicability. We present a classification of major depressive disorder episodes based on the proximate mechanisms that led to the original mood change that caused the depressive episode. We identify discrete depression subtypes that are induced by: 1) infection, 2) long-term stress, 3) loneliness, 4) traumatic experience, 5) hierarchy conflict, 6) grief, 7) romantic rejection, 8) postpartum events, 9) the season, 10) chemicals, 11) somatic diseases and 12) starvation. We further examine the ultimate functions of these subtypes and show that not all types of mood changes that trigger depression are adaptive. Instead, some are clearly maladaptive and some are byproducts of other adaptations. In modern societies, low mood after adverse life events may turn into a pathological depressive state. Modern lifestyle increases susceptibility to inflammatory dysregulation and chronic stress, both of which increase the amount of proinflammatory cytokines in peripheral blood, leading to low mood and sickness behaviour. Proinflammatory cytokines may aggravate the previously adaptive short-term mood changes to a chronic maladaptive depressive state by preventing the normalization of mood after adverse life events. Subtyping depression enables an effective and intelligent long-term treatment of patients in each subtype by treating the underlying causes of depression.

Seasonal Variation in Bright Daylight Exposure, Mood and Behavior among a Group of Office Workers in Sweden

The purpose of the study was to investigate seasonal variation in mood and behavior among a group of office workers in Sweden (56°N). Thirty subjects participated in this longitudinal study. The subjects kept a weekly log that included questionnaires for ratings of psychological wellbeing and daily sleep-activity diaries where they also noted time spent outdoors. The lighting conditions in the offices were subjectively evaluated during one day, five times over the year. There was a seasonal variation in positive affect and in sleep-activity behavior. Across the year, there was a large variation in the total time spent outdoors in daylight. The subjects reported seasonal variation concerning the pleasantness, variation and strength of the light in the offices and regarding the visibility in the rooms. Finally, the subjects spent most of their time indoors, relying on artificial lighting, which demonstrates the importance of the lighting quality in indoor environments.

Effects of genetic variants of ST8SIA2 and NCAM1 genes on seasonal mood changes and circadian preference in the general population

ST8SIA2 and NCAM1 are functionally related genes forming polysialic acid (PSA) - neural cell adhesion molecule (NCAM) complex in suprachiasmatic nucleus (SCN), the regulating site of circadian biological rhythm. In this study, the relationship of ST8SIA2 and NCAM1 with circadian and seasonal rhythms of human behavior was explored. Subjects were 261 healthy Korean adults who were free of any history of clinically significant psychiatric symptoms. The phenotypes were circadian preference and seasonal change of mood and behavior (seasonality) measured by the Composite Scale of Morningness and the Seasonal Pattern Assessment Questionnaire, respectively. Thirty-four single nucleotide polymorphisms (SNPs) across the ST8SIA2 region and 15 SNPs of NCAM1 were analyzed. A nominally significant association with seasonality and circadian preference was observed in 21 variants of both genes. After corrections for multiple testing, associations of 8 SNPs of ST8SIA2 and 2 SNPs of NCAM1 with seasonality remained significant. Some of these SNPs were also associated with psychiatric disorders in previous studies. This study demonstrated a meaningful and/or suggestive evidence of association between behavioral phenotypes reflecting human biological rhythm and two interplaying genes involved in the plasticity of SCN's neuronal network.

Major Depression Prevalence Increases with Latitude in Canada

OBJECTIVE

To determine whether there is an association between latitude and annual major depressive episode (MDE) prevalence in Canada.

METHODS

Data from 2 national survey programs (the National Population Health Survey and the Canadian Community Health Survey) were used, providing 10 data sets collected between 1996 and 2013, together including 922,260 respondents, of whom 495,739 were assessed for MDE using 1 of 2 versions of the Composite International Diagnostic Interview, a short-form version (8 studies), and a Canadian adaptation of the World Mental Health version (2 studies). Approximate latitude was determined by linkage to postal code data. Data were analyzed using logistic regression and pooled across surveys using individual-level meta-analytic methods.

RESULTS

In models including latitude as a continuous variable, a statistically significant association was observed, with prevalence increasing with increasing latitude. This association persisted after adjustment for a set of known risk factors. The latitude gradient was modest in magnitude, a 1% to 2% increase in the prevalence odds of MDE per degree of latitude was observed. Due to sparse data, this gradient cannot be confidently generalized beyond major population centres, which tend to occur at less than 55° latitude in Canada.

CONCLUSION

A latitude gradient has not previously been reported. If replicated, the gradient may have implications for the planning of services and generation of aetiological hypotheses. However, this cross-sectional analysis cannot confirm aetiology and could not evaluate the potential contributions of variables such as light exposure, weather patterns, or social determinants.

CRY1 and CRY2 genetic variants in seasonality: A longitudinal and cross-sectional study

Cryptochromes are key components of the circadian clocks that generate and maintain seasonal variations. The aim of our study was to analyze the associations of CRY1 and CRY2 genetic variants with the problematicity of seasonal variations, and whether the problematicity of seasonal variations changed during the follow-up of 11 years. Altogether 21 CRY1 and 16 CRY2 single-nucleotide polymorphisms (SNPs) were genotyped and analyzed in 5910 individuals from a Finnish nationwide population-based sample who had filled in the self-report on the seasonal variations in mood and behavior in the year 2000. In the year 2011, 3356 of these individuals filled in the same self-report on the seasonal variations in mood and behavior. Regression models were used to test whether any of the SNPs associated with the problematicity of seasonal variations or with a change in the problematicity from 2000 to 2011. In the longitudinal analysis, CRY2 SNP rs61884508 was protective from worsening of problematicity of seasonal variations. In the cross-sectional analysis, CRY2 SNP rs72902437 showed evidence of association with problematicity of seasonal variations, as did SNP rs1554338 (in the MAPK8IP1 and downstream of CRY2).

Winter is coming: nightmares and sleep problems during seasonal affective disorder

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.

Eveningness relates to burnout and seasonal sleep and mood problems among young adults

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.

Natural light exposure, sleep and depression among day workers and shiftworkers at arctic and equatorial latitudes

OBJECTIVES

This study aimed to investigate the relationship between individual natural light exposure, sleep need, and depression at two latitudes, one extreme with a few hours of light per day during winter, and the other with equal hours of light and darkness throughout the year.

METHODS

This cross-sectional study included a sample of Brazilian workers (Equatorial, n = 488 workers) and a Swedish sample (Arctic, n = 1,273).

RESULTS

The reported mean total natural light exposure per 4-week cycle differed significantly between the Equatorial and Arctic regions. However, shiftworkers from both sites reported similar hours of natural light exposure. Short light exposure was a predictor for insufficient sleep.

CONCLUSION

Reduced exposure to natural light appears to increase the perception of obtaining insufficient sleep. Arctic workers were more prone to develop depression than Equatorial workers.

Prevalence, behavioral manifestations and associated individual and climatic factors of seasonality in the Korean general population

BACKGROUNDS

Seasonality, an individual trait of seasonal variations in mood and behavior, has received clinical attention for its association with mood disorders. This study aimed to explore the prevalence, specific manifestation, and associated individual and climatic factors of seasonality in the non-elderly adult population.

METHODS

Five hundred fifty-two participants [male n=220; female n=332; mean age 34.92years, standard deviation (SD) 10.18] with no psychiatric history were recruited from the Seoul metropolitan area (37°33'58.87″N 126°58'40.63″E). Seasonality was evaluated using the Seasonal Pattern Assessment Questionnaire. Climatic variables used in analyses were averaged over recent 5years (from 2008 to 2013) on a monthly basis.

RESULTS

The mean global seasonality score (GSS) was 5.53 (SD 3.91), and 16.2% (n=89) of participants had seasonal affective disorder (SAD) or sub-SAD. The "feeling worst" month in most of the participants with significant seasonality were winter (41.6%) or summer (38.2%). Socio-demographic factors including age and sex were not related to the seasonality. Decreased sunlight amount and diurnal temperature range in a given and previous month, and increased humidity in a previous month showed significant associations with the percentage of participants with the worst mood. The most frequently reported symptom related to seasonality was 'changes in energy level'. Specific manifestations were not significantly different between the winter type and the summer type.

CONCLUSION

The summer and winter type seasonality in the non-clinical adult population did not differ in terms of behavioral manifestations. Decreased sunlight amount, diurnal temperature range, and increased humidity appeared to be major climatic factors associated with seasonality.

Natural light exposure, sleep and depression among day workers and shiftworkers at arctic and equatorial latitudes

OBJECTIVES

This study aimed to investigate the relationship between individual natural light exposure, sleep need, and depression at two latitudes, one extreme with a few hours of light per day during winter, and the other with equal hours of light and darkness throughout the year.

METHODS

This cross-sectional study included a sample of Brazilian workers (Equatorial, n = 488 workers) and a Swedish sample (Arctic, n = 1,273).

RESULTS

The reported mean total natural light exposure per 4-week cycle differed significantly between the Equatorial and Arctic regions. However, shiftworkers from both sites reported similar hours of natural light exposure. Short light exposure was a predictor for insufficient sleep.

CONCLUSION

Reduced exposure to natural light appears to increase the perception of obtaining insufficient sleep. Arctic workers were more prone to develop depression than Equatorial workers.

Sleep and sickness absence: a nationally representative register-based follow-up study

STUDY OBJECTIVES

We aimed to examine various sleep measures as determinants of sickness absence while considering confounders.

DESIGN

Nationally representative Health 2000 Survey linked with sickness absence data from the Finnish Social Insurance Institution.

SETTING

Finland.

PARTICIPANTS

Working-aged women (n = 1,875) and men (n = 1,885).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Insomnia-related symptoms, early morning awakenings, being more tired during daytime than other people of same age, use of sleeping pills, excessive daytime sleepiness, probable sleep apnea (4 items about snoring/apnea), and reporting that sleep duration varies between different seasons were examined as determinants of sickness absence over a 7.2 year follow-up. Poisson and gamma regression models were fitted. After adjusting age, all examined sleep disturbances except excessive daytime sleepiness were associated with sickness absence among men (RRs 1.3-2.5). Among women, after adjusting for age, insomnia-related symptoms, early morning awakenings, being more tired than others, and use of sleeping pills were associated with sickness absence (RRs 1.4-1.8). After further adjustments for education, working conditions, health behaviors, and objectively measured mental and somatic health, the associations somewhat attenuated but mainly remained. The optimal sleep duration with the lowest risk of sickness absence was 7.6 hours for women and 7.8 hours for men. Although persistence of other health problems could affect the estimates, direct costs due to sickness absence could decrease by up to 28% if sleep disturbances could be fully addressed.

CONCLUSIONS

This study highlights the need for prevention of sleep disturbances and promotion of optimal sleep length to prevent sickness absence.

The influence of light administration on interpersonal behavior and affect in people with mild to moderate seasonality

Bright light is used to treat winter depression and may also have positive effects on mood in some healthy individuals. However, there is little information on how bright light treatment influences social behavior. We performed a cross-over study in winter comparing the effects of morning bright light administration with placebo (exposure to negative ions) on mood and social behavior in 38 healthy people with mild to moderate seasonality. Each treatment was given for 21days with a washout period of 14days between treatments. An event-contingent recording assessment was used to measure mood, and social behavior along two axes, agreeable-quarrelsome and dominant-submissive, during each 21-day treatment period. During treatments, participants wore a combined light-sensor and accelerometer to test this method for adherence to light treatment self-administered at home. Data were analyzed using multilevel modeling. Bright light improved mood but increased quarrelsome behavior and decreased submissiveness. Data from the light monitor and accelerometer suggested that 21% of the participants did not adhere to bright light treatment; when this group was analyzed separately, there was no change in quarrelsomeness or mood. However, results for individuals who followed the procedure were similar to those reported for the whole sample.

Influence of seasonal variation in mood and behavior on cognitive test performance among young adults

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.

Insomnia and the Risk of Acute Myocardial Infarction

Background—

Few prospective studies have investigated insomnia in relation to risk for coronary heart disease. We assessed insomnia symptoms and risk of acute myocardial infarction (AMI) in a large, population-based study.

Methods and Results—

A total of 52 610 men and women were followed up for a first AMI, and 2368 incident AMIs occurred during 11.4 years of follow-up, either identified at hospitals or by the National Cause of Death Registry. In our analyses, we adjusted for age, sex, marital status, education, shift work, blood pressure, lipids, diabetes mellitus, body mass index, physical activity, smoking, and alcohol consumption. Difficulties initiating and maintaining sleep and having a feeling of nonrestorative sleep were associated with a moderate increase in AMI risk. The multiadjusted hazard ratios for AMI were 1.45 (95% confidence interval 1.18–1.80) for people with difficulties initiating sleep almost every night, 1.30 (1.01–1.68) for those with difficulties maintaining sleep almost every night, and 1.27 (1.03–1.57) for those with a feeling of nonrestorative sleep more than once a week compared with people who never experienced these sleep difficulties. When we combined the symptoms, a dose-dependent association was seen between the number of insomnia symptoms and AMI risk ( P for trend 0.003). Alternative multivariable models and different sensitivity analyses suggest that the results were robust, especially concerning difficulties initiating sleep.

Conclusions—

Insomnia is associated with a moderately increased risk for AMI.

Seasonal symptoms in bipolar and primary care patients

BACKGROUND

There is evidence of seasonality in bipolar affective disorder (BAD) and the preponderance of atypical symptoms in bipolar depressive episodes is also seen in winter type Seasonal Affective Disorder. Differences in seasonal symptoms between BAD and appropriate comparison populations have been scrutinised only in small studies.

METHODS

Symptoms described on the Seasonal Pattern Assessment Questionnaire (SPAQ) were compared between 183 patients with BAD and 468 patients consulting their general practitioners. Statistical analyses were adjusted for differing age and gender distributions between the two groups.

RESULTS

Compared with the general practice patients, subjects with BAD reported greater seasonal fluctuations in mood (p=0.003). On one measure BAD subjects reported increased seasonal changes in social activity (p<0.001) and greater weight fluctuation over the year (p=0.001). The most striking differences were in sleep patterns; BAD subjects slept significantly more throughout the year, and slept for a mean of 1.8h more in winter than in summer (versus a 1.0h difference in the general practice group, p<0.001). Against 20% of the general practice group, 46% of BAD patients rated seasonal changes in well-being to be at least a moderate problem.

LIMITATIONS

The SPAQ was designed as a screening instrument for Seasonal Affective Disorder, not for studies of this nature. Some of the reported differences, notably in social activity and weight changes, may reflect secondary psychosocial effects of BAD.

CONCLUSIONS

Seasonal changes, most notably winter hypersomnia, should be identified in patients with BAD. These symptoms may respond to treatments such as light therapy that are used in recurrent winter depression.

The effect of seasons and seasonal variation on neuropsychological test performance in patients with bipolar I disorder and their first-degree relatives

BACKGROUND

Bipolar disorder (BD) patients have cognitive deficits that may remain in the euthymic phase. Similar although milder cognitive deficits may be found in their first-degree relatives. We wanted to analyze whether the self-report of seasonality, the season when individuals were tested or the circadian preference influences the neuropsychological test performance measured in the familial BD, type I, patients and their healthy first-degree relatives.

METHOD

A structured diagnostic interview (SCID) and neuropsychological test battery were administered to 32 familial BD type I patients, 40 of their unaffected first-degree relatives and 50 controls, all from population-based samples. BD patients and their relatives filled in the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Horne-Östberg Morningness-Eveningness Questionnaire (MEQ).

RESULTS

Individuals, who reported that seasonal variation was a problem, scored worse on the measures of visuoconstructional functions, visuospatial reasoning, auditory attention and working memory, and verbal memory than those with no seasonal variation. The season when tested had an influence on test performance. Individuals from the families that were tested in spring, summer and autumn scored better than those tested in winter on the measures of visual and verbal attention, working memory, verbal ability, verbal fluency, and executive functioning. Among the controls there was no difference in the test scores from season to season. The circadian preference had no effect on test performance.

LIMITATIONS

Only relatives, not BD patients were tested in winter.

CONCLUSION

Seasonal variation in mood and behavior as a problem in patients and their first-degree relatives influences negatively the neuropsychological test performance. In addition, among the patients and first-degree relatives the neuropsychological test performance in winter may be worse than in other seasons.