Mood Seasonality Research Articles

Seasonal variation in D2/3 dopamine receptor availability in the human brain

PurposeBrain functional and physiological plasticity is essential to combat dynamic environmental challenges. The rhythmic dopamine signaling pathway, which regulates emotion, reward and learning, shows seasonal patterns with higher capacity of dopamine synthesis and lower number of dopamine transporters during dark seasons. However, seasonal variation of the dopamine receptor signaling remains to be characterized.MethodsBased on a historical database of healthy human brain [11C]raclopride PET scans (n = 291, 224 males and 67 females), we investigated the seasonal patterns of D2/3 dopamine receptor signaling. Daylength at the time of scanning was used as a predictor for brain regional non-displaceable binding of the radiotracer, while controlling for age and sex.ResultsDaylength was negatively correlated with availability of D2/3 dopamine receptors in the striatum. The largest effect was found in the left caudate, and based on the primary sample, every 4.26 h (i.e., one standard deviation) increase of daylength was associated with a mean 2.8% drop (95% CI -0.042 to -0.014) of the receptor availability.ConclusionsSeasonally varying D2/3 receptor signaling may also underlie the seasonality of mood, feeding, and motivational processes. Our finding suggests that in future studies of brain dopamine signaling, especially in high-latitude regions, the effect of seasonality should be considered.

Mood seasonality around the globe

This paper examines the existence of mood seasonality, documented by Hirshleifer et al. (2020, JFE) for the cross-section of US equity returns, in an international setting. First, we confirm the results of the original study. Next, we extend these findings to non-US markets and show that they are not sample-specific. A stock's relative historical seasonal returns are positively correlated with its relative future seasonal returns during similar or congruent mood periods and negatively related with its relative future seasonal returns during dissimilar or non-congruent mood periods. Moreover, both regression and portfolio analyses indicate that mood beta, the sensitivity of equity returns to aggregate investor mood, helps explain these mood seasonality effects.

The seasonality of lottery-like stock returns

Using daily stock returns over 38 years, we extend the mood seasonality hypothesis to examine whether seasonal anomalies are more pronounced in stocks with lottery-like features preferred by individual investors. We find that the strength of various stock return seasonality patterns is significantly associated with stocks’ lottery-likeness. The seasonality patterns of positive January and pre-holiday performance, and negative Monday performance are all enhanced the more lottery-like a stock is. Additional analysis for different prosperity periods indicates support for Prospect Theory. Overall, our results are consistent with investor mood seasonality (and consequential risk-tolerance) being expressed via speculative investments.

Junk Stocks vs Quality Stocks, A Perspective from Mood Seasonality

ABSTRACT Based on their own quality measure, Asness et al. (2019) document that quality stocks significantly outperform junk stocks. In this article, we attempt to explore the quality-based return patterns from behavioural perspective. The empirical findings demonstrate that the relative performance of quality stocks exhibits significant mood seasonality, i.e. the return spreads of quality and junk stocks decrease (increase) during high (low)-mood months. Furthermore, we also find that the return spreads exhibit significant mood recurrence and reversal effects proposed by Hirshleifer et al. (2020). All of these findings support the argument that mood would be an important source for the outperformance of quality stocks.

Mood seasonality: Evidence from the Chinese A-share market

Seasonality is typical in the stock market, and a specific month reflects investors' mood. During the same calendar months, the cross-sectional stocks' better or worse performance relative to other stocks in specific months signifies investor mood seasonality. Using the Chinese A-share market's monthly data from 1999 to 2019, we find that the mood seasonality effect is significant. Besides, there is a positive relationship between mood beta and stock return during a congruent mood period. Moreover, the investment strategy can obtain a significantly positive average return based on February's mood beta.

Testing the mood seasonality hypothesis: Evidence from down under

We examine whether seasonal variations in investor mood are associated with return seasonalities in U.S. and Australian equity markets. We first replicate the main results of Hirshleifer et al. (2020) for the U.S. market that stock returns' relative performance during past high or low mood periods tends to recur in periods with congruent mood but reverse in periods with noncongruent mood. We next test the mood seasonality hypothesis in Australia (Southern hemisphere), where the calendar timing of seasons is opposite to that experienced in the United States (Northern hemisphere). This enables us to identify whether the seasonally varying investor mood effect on returns is independent of the actual calendar month. In the Australian market we also find the congruent-mood recurrence and noncongruent-mood reversal effects under our hypothesized high and low mood months, and this effect is particularly strong for the full cross-section of individual assets.

Seasonality of mood and affect in a large general population sample.

Mood and behaviour are thought to be under considerable influence of the seasons, but evidence is not unequivocal. The purpose of this study was to investigate whether mood and affect are related to the seasons, and what is the role of neuroticism in this association. In a national internet-based crowdsourcing project in the Dutch general population, individuals were invited to assess themselves on several domains of mental health. ANCOVA was used to test for differences between the seasons in mean scores on the Positive and Negative Affect Schedule (PANAS) and Quick Inventory of Depressive Symptomatology (QIDS). Within-subject seasonal differences were tested as well, in a subgroup that completed the PANAS twice. The role of neuroticism as a potential moderator of seasonality was examined. Participants (n = 5,282) scored significantly higher on positive affect (PANAS) and lower on depressive symptoms (QIDS) in spring compared to summer, autumn and winter. They also scored significantly lower on negative affect in spring compared to autumn. Effect sizes were small or very small. Neuroticism moderated the effect of the seasons, with only participants higher on neuroticism showing seasonality. There was no within-subject seasonal effect for participants who completed the questionnaires twice (n = 503), nor was neuroticism a significant moderator of this within-subjects effect. The findings of this study in a general population sample participating in an online crowdsourcing study do not support the widespread belief that seasons influence mood to a great extent. For, as far as the seasons did influence mood, this only applied to highly neurotic participants and not to low-neurotic participants. The underlying mechanism of cognitive attribution may explain the perceived relation between seasonality and neuroticism.

Mood Worsening on Days with High Pollen Counts is associated with a Summer Pattern of Seasonality.

Background:Summer/spring-type seasonal affective disorder (S-SAD) is the less common subtype of seasonal affective disorder and evidence regarding potential triggers of S-SAD is scarce. Recent reports support association of airborne-pollen with seasonal exacerbation of depression (mood seasonality) and timing of suicidal behavior. Therefore, we hypothesized that Old Order Amish (OOA) with summer/spring pattern of seasonality (abbreviated as summer pattern) and S-SAD will have significant mood worsening on high pollen days.Methods:A seasonal pattern of mood worsening and SAD parameters were estimated using Seasonal Pattern Assessment Questionnaire (SPAQ). Age- and gender-adjusted ANCOVAs and post hoc analyses were conducted to compare mood worsening on days with high pollen counts between summer-pattern vs no-summer-pattern of mood worsening, S-SAD vs no-S-SAD, winter-pattern vs no-winter-pattern of mood worsening, and W-SAD vs no-W-SAD groups.Results:The prevalence of S-SAD was 0.4%, while 4.5% of individuals had a summer pattern of mood seasonality. A statistically significant difference for mood worsening on high pollen days was observed between summer-pattern vs no-summer-pattern of mood worsening (p = 0.006). The significant association between S-SAD vs no-SAD groups (p = 0.032) for mood worsening on high pollen days did not withstand Bonferroni adjustment for multiple comparisons. No significant association was found for winter-pattern vs no-winter-pattern of mood worsening (p = 0.61) and for W-SAD vs no-W-SAD (p = 0.19) groups.Conclusion:Our results are consistent with previous studies implicating links between aeroallergen exposure and summer pattern of seasonality, but not the winter pattern of seasonality.

Seasonality of blood neopterin levels in the Old Order Amish.

Seasonal changes in non-human animals and seasonal affective disorder (SAD) in humans are associated with immune activation in winter relative to summer. We intended to measure seasonal variation in neopterin, a marker of cellular immunity, and its interactions with gender and seasonality of mood. We studied 320 Amish from Lancaster, PA, USA (men = 128; 40%) with an average age [Standard deviation (SD)] of 56.7 (13.9) years. Blood neopterin level was measured with enzyme-linked immunosorbent assay (ELISA). Seasonality was measured with Seasonal Pattern Assessment Questionnaire (SPAQ). Statistical analysis included analysis of covariance (ANCOVAs) and multivariate linear regression. We also investigated interactions of seasonal differences in neopterin with gender, seasonality scores and estimation of SAD diagnosis. We found a significantly higher neopterin level in winter than in summer (p = 0.006). There were no significant gender or seasonality interactions. Our study confirmed the hypothesized higher neopterin level in winter. A cross sectional design was our major limitation. If this finding will be replicated by longitudinal studies in multiple groups, neopterin could be used to monitor immune status across seasons in demographically diverse samples, even if heterogeneous in gender distribution, and degree of seasonality of mood.

The Effect of Photoperiod on the Mood of Reddit Users

Research into the seasonality of mood has long been stymied by a lack of data, in part due to the prohibitive cost of traditional data collection and the tendency for data to be highly localized. Recent work using social media data has evinced the utility of psycholinguistic features in tracking mood and mental illness, but Twitter data, which are nonanonymous and short-form by design, have almost exclusively been the subject of analysis. In this article, we present a novel corpus within this field of study, comments from the social network Reddit, which does not suffer from these potential limitations. We find that although there are no notable changes in mood in the entire population over the course of a year, a small cohort is acutely sensitive to changes in the relative day length (i.e., the relative photoperiod). Our findings corroborate the phase shift hypothesis, which is the prevailing theory for the seasonality of mood. We also demonstrate the viability of the Reddit comments corpus for studies in mood and, more broadly, mental health.

Seven-year survey of sleep timing in Russian children and adolescents: chronic 1-h forward transition of social clock is associated with increased social jetlag and winter pattern of mood seasonality

Previous studies indicate that solar clock (daily changes in the Earth’s surface illumination) is a main zeitgeber for human circadian system. It has been shown that human biological clock is weakly adjusted to such changes in social clock as daylight saving time (DST). There are two changes of social clock in Russian Federation: on 25 March 2011, DST has been replaced by permanent DST (DSTp), which was subsequently revoked on 26 October 2014 (non-DSTp). These manipulations with social clock may lead to prolonged disturbances of human circadian system. Our hypothesis is that during period of DSTp, the dissociation between social and biological clocks was greatest as compared with DST and non-DSTp periods. Here, we examine the effects of DSTp on the sleep timing, social jetlag (SJL), academic performance, and winter and summer seasonality of mood and behavior of 10–24-year-old inhabitants of European North of Russia. A cross-sectional retrospective analysis of questionnaire data (n = 7968) was performed using chi squared-test and analysis of covariance. Our findings indicate that SJL (F2,7967 = 31.9; p < 0.0001; η2 = 0.009), and winter pattern of mood seasonality (χ22,7967 = 10.5; p < 0.01) were increased in adolescents during the period of DSTp as compared with DST and non-DSTp periods. The largest increase in SJL was occurred in ages between 10 and 17-year-olds. The finding suggests that increase in SJL can be attributed to a later rise time on free days (F2,7967 = 44.9; p < 0.0001; η2 = 0.012). Similar changes were observed in three subsamples obtained in Syktyvkar, Petrozavodsk, and Vorkuta. Effect sizes of studied relationships were small or very small. The greatest effect sizes (η2 ∼ 0.05) were observed in Arctic city of Vorkuta indicating that in polar region, solar clock is still stronger zeitgeber for human circadian system, than the social clock. In conclusion, we have shown for the first time that there is a greatest dissociation between social and biological clocks during the period of DSTp which potentially exerts a negative influence on adolescents’ sleep habits, mood, and behavior. Our data indicate that “non-DSTp” social clock system most suitable for prevention dissociation between social and biological clocks.

Seasonal variation in major depressive episode prevalence in Canada.

The purpose of this paper is to describe variation, over the months of the year, in major depressive episode (MDE) prevalence. This is an important aspect of the epidemiological description of MDE, and one that has received surprisingly little attention in the literature. Evidence of seasonal variation in MDE prevalence has been weak and contradictory. Most studies have sought to estimate the prevalence of seasonal affective disorder using cut-points applied to scales assessing mood seasonality rather than MDE. This approach does not align with modern classification in which seasonal depression is a diagnostic subtype of major depression rather than a distinct category. Also, some studies may have lacked power to detect seasonal differences. We addressed these limitations by examining the month-specific occurrence of conventionally defined MDE and by pooling data from large epidemiological surveys to enhance precision in the analysis. Data from two national survey programmes (the National Population Health Survey and the Canadian Community Health Survey) were used, providing ten datasets collected between 1996 and 2013, together including over 500,000. These studies assessed MDE using a short form version of the Composite International Diagnostic Interview (CIDI) for major depression, with one exception being a 2012 survey that used a non-abbreviated version of the CIDI. The proportion of episodes occurring in each month was evaluated using items from the diagnostic modules and statistical methods addressing complex design features of these trials. Overall month-specific pooled estimates and associated confidence intervals were estimated using random effects meta-analysis and a gradient was assessed using a meta-regression model that included a quadratic term. There was considerable sampling variability when the month-specific proportions were estimated from individual survey datasets. However, across the various datasets, there was sufficient homogeneity to justify the pooling of these estimated proportions, producing large gains in precision. Seasonal variation was clearly evident in the pooled data. The highest proportion of episodes occurred in December, January and February and the lowest proportions occurred in June, July and August. The proportion of respondents reporting MDE in January was 70% higher than August, suggesting an association with implications for health policy. The pattern persisted with stratification for age group, sex and latitude. Seasonal effects in MDE may have been obscured by small sample sizes in prior studies. In Canada, MDE has clear seasonal variation, yet this is not addressed in the planning of services. These results suggest that availability of depression treatment should be higher in the winter than the summer months.

Chronotype and seasonality: Morningness is associated with lower seasonal mood and behavior changes in the Old Order Amish

BackgroundSeveral studies documented that lower scores on the Morningness–Eveningness Questionnaire (MEQ) are associated with a higher global seasonality of mood (GSS). As for the Modern Man artificial lighting predominantly extends evening activity and exposure to light, and as evening bright light phase is known to delay circadian rhythms, this chronic exposure could potentially lead to both lower Morningness as well as higher GSS. The aim of the study was to investigate if the MEQ–GSS relationship holds in the Old Order Amish of Lancaster County, PA, a population that does not use network electrical light. Methods489 Old Order Amish adults (47.6% women), with average (SD) age of 49.7 (14.2) years, completed both the Seasonal Pattern Assessment Questionnaire (SPAQ) for the assessment of GSS, and MEQ. Associations between GSS scores and MEQ scores were analyzed using linear models, accounting for age, gender and relatedness by including the relationship matrix in the model as a random effect. ResultsGSS was inversely associated with MEQ scores (p=0.006, adjusted). Limitationsinclude a potential recall bias associated with self-report questionnaires and no actual light exposure measurements. ConclusionWe confirmed the previously reported inverse association between MEQ scores and lower seasonality of mood, for the first time in a population that does not use home network electrical lighting. This result suggests that the association is not a byproduct of exposure to network electric light, and calls for additional research to investigate mechanisms by which Morningness is negatively associated with seasonality.

SELF-ATTRIBUTED SEASONALITY OF MOOD AND BEHAVIOR: A REPORT FROM THE NETHERLANDS STUDY OF DEPRESSION AND ANXIETY

Seasonal changes in mood and behavior are considered to be common in the general population and in patients with psychiatric disorders. However, in several studies this seasonality could not be demonstrated. The present study examined self-attributed seasonality of depressive symptoms among patients with a lifetime diagnosis of a depressive disorder (D), an anxiety disorder (A), a comorbid depressive and anxiety disorder (DA), and healthy controls (HC). The CIDI was used to establish diagnoses according to DSM-IV criteria in 2,168 participants of the Netherlands Study of Depression and Anxiety (NESDA). The Seasonal Pattern Assessment Questionnaire (SPAQ) was administered to assess variation in mood and behavior. Of the 2,168 participants 53.5% reported seasonality of mood. Highest percentages of low mood were seen in the winter months. Although all groups showed this pattern of lowered mood during the winter months, D, A, and DA were significantly (P < .001) more likely to experience seasonality is this respect. This was also shown for seasonal changes in energy, social activities, sleeping, eating, weight and for the Global Seasonality Score. A limitation of this study was the cross-sectional design. Seasonal variation in mood and behavior was demonstrated for both participants with a lifetime diagnosis of depression and/or anxiety disorder and for healthy controls, but patients with anxiety and/or depression were more likely to experience this seasonal variation. Clinicians should take into account that the time of the year could influence the feelings of well- and ill-being of their patients.

Month of birth and mood seasonality: A comparison between countries in the northern and southern hemispheres

A previous study has reported a significant month-of-birth effect on mood seasonality in the northern hemisphere. Higher mood seasonality was observed for university students born during spring or summer months (long photoperiod) compared to those born during autumn or winter months (short photoperiod). The aim of this study was to test the hypothesized photoperiod effect by comparing the correlation between month of birth and mood seasonality in two countries located at the opposite poles of the terrestrial globe: Italy (northern hemisphere) and New Zealand (southern hemisphere). On the basis of the photoperiod-at-birth hypothesis, we expected to find higher mood seasonality among individuals born in months with longer photoperiods in both countries. The Seasonal Pattern Assessment Questionnaire was administered to 1514 young adults (1088 women, 426 men; 1027 Italians, 487 New Zealanders), with ages ranging from 18 to 34 years. The Global Seasonality Score, which is a measure of mood seasonality, was calculated from the Seasonal Pattern Assessment Questionnaire. A significant overall month-of-birth effect was observed on the Global Seasonality Score, but only for men. Men born in April and August (corresponding in Italy to a long photoperiod, in New Zealand to a short photoperiod) had higher mood seasonality than those born in February, regardless of country. A significant month-of-birth effect was found on mood seasonality, but results do not support the hypothesis based on the photoperiod effect.

Seasonality of mood and behavior in the Old Order Amish

Background/ObjectiveWe examined seasonality and winter seasonal affective disorder (SAD) in the Old Order Amish of Lancaster County, Pennsylvania, a unique population that prohibits use of network electric light in their homes. MethodsWe estimated SAD using the seasonal pattern assessment questionnaire (SPAQ) in 1306 Amish adults and compared the frequencies of SAD and total SAD (i.e., presence of either SAD or subsyndromal-SAD) between men and women, young and old, and awareness of (ever vs. never heard about) SAD. Heritability of global seasonality score (GSS) was estimated using the maximum likelihood method, including a household effect to capture shared environmental effects. ResultsThe mean (±SD) GSS was 4.36 (±3.38). Prevalence was 0.84% (95% CI: 0.36–1.58) for SAD and 2.59% (95% CI: 1.69–3.73) for total SAD. Heritability of GSS was 0.14±0.06 (SE) (p=0.002) after adjusting for age, gender, and household effects. LimitationsLimitations include likely overestimation of the rates of SAD by SPAQ, possible selection bias and recall bias, and limited generalizability of the study. ConclusionsIn the Amish, GSS and SAD prevalence were lower than observed in earlier SPAQ-based studies in other predominantly Caucasian populations. Low heritability of SAD suggests dominant environmental effects. The effects of awareness, age and gender on SAD risk were similar as in previous studies. Identifying factors of resilience to SAD in the face of seasonal changes in the Amish could suggest novel preventative and therapeutic approaches to reduce the impact of SAD in the general population.

Circadian type and mood seasonality in adolescents

The aim of the present study was to investigate, for the first time, the relationship between circadian preference and mood seasonality in adolescents. To this end, 1539 participants (881 female; 658 male) completed the Morningness-Eveningness Questionnaire for Children and Adolescents and the Seasonal Pattern Assessment Questionnaire for Children and Adolescents to determine circadian preference and mood seasonality, respectively. Evening types achieved significantly higher mood seasonality scores than intermediate and morning types, as intermediates did than morning types. Agreeing with previous studies on young adults and adults, the present data indicate a significant relationship between eveningness and higher mood seasonality in adolescents.

Cross-national survey of winter and summer patterns of mood seasonality: a comparison between Italy and India

The aim of this study was to compare winter and summer patterns of mood seasonality in university students living at different latitudes: Bologna, 44° N (Italy), and Kalyani, 22° N (India). To assess the mood seasonality, the Seasonal Pattern Assessment Questionnaire was administered to 1370 university students (808 females, 562 males; 862 Italians, 508 Indians), ranging in age between 18 and 28 years. A significantly higher Global Seasonality Score was observed in females than males as well as in Italians than Indians. The estimated rates of summer seasonal affective disorder (SAD) and summer subsyndromal SAD were higher in Indians, whereas Italians reported higher percentage of winter SAD and winter subsyndromal SAD. The present findings are discussed in relation to the different environmental features between the 2 countries: high summer temperature in India and short winter photoperiod along with its great excursion over the year in Italy.

Female gender but not season of birth is associated with mood seasonality in a near-equatorial Brazilian city

OBJECTIVE: Studies conducted mainly in countries located in the Northern Hemisphere have shown that season of birth influences mood seasonality. Greater mood seasonality has been observed for individuals born during spring/summer months than those born during autumn/winter months. Expanding past research to the Southern Hemisphere, in this study we examine the influence of season of birth on mood seasonality in a sample of 1,247 healthy young Brazilians. METHOD: The Seasonal Pattern Assessment Questionnaire was used to compute a global seasonality score as a measure of mood seasonality in a cross-sectional study. RESULTS: Analysis of covariance was conducted to examine the effects of month of birth and gender on mood seasonality, with age entered as a covariate. A main effect of gender was observed, F (1, 1197) = 17.86, p &lt; .01; partial Eta-squared = .02, with mood seasonality being higher for females (M = 8) than for males (M = 7). Contradicting previous findings, no significant main effect for month of birth was observed, F (1, 1197) = 0.65, p &gt; .05. CONCLUSION: The unexpected finding is tentatively explained by differences in geographic location and weather fluctuations between the sampling location in Brazil and other countries where season of birth has been found to influence mood seasonality. Additional studies with larger samples from the Southern Hemisphere are necessary to shed additional light on the possible significant influence of season of birth on mood.

Season of birth and mood seasonality in late childhood and adolescence

A significant season of birth effect on mood seasonality has been detected in young adults, with higher sensitivity to seasonal changes for people born during spring or summer months (long photoperiod) than those born during autumn or winter months (short photoperiod). The aim of this study was to verify whether the birth season effect on mood seasonality is already present in late childhood and adolescence. To this end, the Seasonal Pattern Assessment Questionnaire for Children and Adolescents (SPAQ-CA) was administered to 1523 Italian participants (870 females, 653 males), ranging from 10 to 17years of age. The Global Seasonality Score (GSS) was computed as a measure of mood seasonality. Analysis of covariance showed a significant season of birth effect on GSS; although no comparisons were significant when Tukey's posthoc test for unequal samples was performed, it was observed that adolescents born in summer achieved the highest scores while those born in winter obtained the lowest. The present data point out that a significant season of birth effect on mood seasonality is already present in late childhood and adolescence.