Seasonal variation of mood and behaviour in a healthy middle-aged population in Japan

Lifestyle modification as intervention for seasonal affective disorder: A systematic review

Bright light therapy (BLT) and pharmacological therapies currently represent the first line treatments for patients with seasonal affective disorder (SAD). Lifestyle modifications offer a diverse field of additional intervention options. Since it is unclear, if lifestyle modifications are effective in SAD patients, this systematic review aims to synthesize the current evidence on their effectiveness and safety. We systematically searched for randomized controlled trials (RCTs) assessing lifestyle modifications (nutrition, exercise, staying outdoors, sleep, social aspects, mindfulness methods) in SAD patients. We defined the primary outcome as the post-therapeutic extent of depressive symptoms, measured by validated psychiatric symptom scales. Due to the insufficient number of studies and the high heterogeneity of the interventions we were not able to calculate a meta-analysis. We identified 6 studies from the following areas of lifestyle modification: diet, exercise, staying outdoors, sleep and music therapy. All studies showed improvements of depression scores in the intervention as well as in the control groups. The risk of bias was rated as high for all studies and the certainty of evidence was rated as very low. The results point towards the possible effectiveness of the interventions examined, but due to the small number of studies found, too small sample sizes and methodological limitations, we cannot draw a valid conclusion about the effectiveness of lifestyle-modifying measures in SAD patients. Larger, high-quality RCTs are needed to make evidence-based recommendations and thus to expand the range of therapeutic options for SAD.

Thermal Comfort and Sleep Quality of Indonesian Students Living in Japan during Summer and Winter

Thermal comfort is crucial in satisfaction and maintaining quality sleep for occupants. In this study, we investigated the comfort temperature in the bedroom at night and sleep quality for Indonesian students during summer and winter. Eighteen male Indonesian students aged 29 ± 4 years participated in this study. The participants had stayed in Japan for about six months. We evaluated the sleep parameters using actigraphy performed during summer and winter. All participants completed the survey regarding thermal sensation, physical conditions, and subjective sleepiness before sleep. The temperature and relative humidity of participants’ bedrooms were also measured. We found that the duration on the bed during winter was significantly longer than that during summer. However, sleeping efficiency during winter was significantly worse than that during summer. The bedroom temperature of the participants was in the range of comfort temperature in Indonesia. With the average bedroom air temperature of 22.2 °C, most of the participants still preferred “warm” and felt “slightly comfortable” during winter. The average comfort temperature each season calculated using the Griffiths method was 28.1 °C during summer and 23.5 °C during winter. In conclusion, differences in adaptive action affect bedroom thermal conditions. Furthermore, habits encourage the sleep performance of Indonesian students.

Self-Isolation Due to COVID-19 Is Linked to Small One-Year Changes in Depression, Sleepiness, and Insomnia: Results from a Clinic for Sleep Disorders in Shiga Prefecture, Japan

We aimed to analyze (a) the changes in depression, sleepiness, insomnia, and sleep habits in relation to the degree of self-isolation and (b) the effects of changes in sleep habits and social interactions on depression, insomnia, and sleepiness during the coronavirus disease 2019 (COVID-19) pandemic. We enrolled 164 patients who visited the sleep outpatient clinic in Shiga University of Medical Science Hospital. We compared the sleep habits, depression (Patient Health Questionnaire-9: PHQ-9), insomnia (Athens Insomnia Scale: AIS), and sleepiness (Epworth Sleepiness Scale: ESS) of patients during the period from April to July 2019 vs. May 2020 (a period of self-isolation due to COVID-19). A Wilcoxon signed-rank test indicated no significant differences in PHQ-9, ESS, and AIS scores between 2019 and 2020 within both the strong self-isolation group and no/little self-isolation group. With respect to sleep habits, earlier bedtime (p = 0.006) and increased sleep duration (p = 0.014) were found in the strong self-isolation group. The former (p = 0.009) was also found in the no/little self-isolation group, but we found significant differences in sleep duration between the no/little self-isolation group and the strong self-isolation group (p = 0.047). Therefore, self-isolation due to COVID-19 had relatively small one-year effects on depression, sleepiness, and insomnia in a clinical population.

Reduction of fatigue and anger-hostility by the oral administration of 5-aminolevulinic acid phosphate: a randomized, double-blind, placebo-controlled, parallel study

Although large populations feel fatigue, the standardized medicinal therapy is currently absent. In this study, we determined whether 5-aminolevulinic acid (5-ALA) supplementation alleviates the feeling of fatigue in healthy subjects who feel chronic physical tiredness. Males and females between ages of 20 and 64 who felt physical fatigue on a daily basis, with a visual analogue scale (VAS) for fatigue ≥ 40 mm, a T-score of Fatigue-Inertia in the Profile of Mood States—Second Edition—Adult (POMS2-A) ≥ 50, and a T-score of Vigor-Activity in POMS2-A ≤ 60 were recruited. Seventy eligible participants were randomly assigned to either a 5-ALA or a placebo group. During the 8 weeks of consumption, the subjects completed VAS questionnaires for fatigue and POMS2-A at 4-week intervals. The VAS values for overall feeling of fatigue and feeling of work-related fatigue, and the Anger-Hostility subscale of POMS2-A were decreased by 5-ALA with significant time × group interaction effects (p = 0.040, 0.020, and 0.045, respectively). Besides, the 5-ALA group showed significant differences in Fatigue-Inertia, Depression-Dejection and Total Mood Disturbance scores, when compared between pre- and post-intervention, while the placebo group did not. In conclusion, the oral administration of 5-ALA improves fatigue and negative mood in subjects who constantly feel physical fatigue.

This clinical trial was registered with University hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) as UMIN000031528 on 2/3/2018.

Prevalence of seasonal depression in a prospective cohort study

The prevalence of autumn/winter seasonality in depression has been documented in the longitudinal Zurich cohort study by five comprehensive diagnostic interviews at intervals over more than 20 years (N = 499). Repeated winter major depressive episodes (MDE-unipolar + bipolar) showed a prevalence of 3.44% (5× more women than men), whereas MDE with a single winter episode was much higher (9.96%). A total of 7.52% suffered from autumn/winter seasonality in major and minor depressive mood states. The clinical interviews revealed novel findings: high comorbidity of Social Anxiety Disorder and Agoraphobia within the repeated seasonal MDE group, high incidence of classic diurnal variation of mood (with evening improvement), as well as a high rate of oversensitivity to light, noise, or smell. Nearly twice as many of these individuals as in the other MDE groups manifested the syndrome of atypical depression (DSM-V), which supports the prior description of seasonal affective disorder (SAD) as presenting primarily atypical symptoms (which include hypersomnia and increase in appetite and weight). This long-term database of regular structured interviews provides important confirmation of SAD as a valid diagnosis, predominantly found in women, and with atypical vegetative symptoms.

Seasonal changes in sleep duration and sleep problems: A prospective study in Japanese community residents

Background

A scientific understanding of the effects of seasonal changes on sleep duration and sleep problems such as insomnia and hypersomnia has yet to be elucidated; however, such an understanding could aid the establishment of an optimal sleep hygiene program to treat such problems.

Methods

We investigated the effects of seasonal changes on sleep duration and sleep problems in Japanese community residents. Data on 1,388 individuals aged 15–89 years who participated in the Survey of Seasonal Variations in Food Intakes conducted by the National Institute of Health and Nutrition of Japan (2004–2007) were analyzed. Participants completed a questionnaire including items on sleep duration and sleep problems (difficulty initiating sleep [DIS], difficulty maintaining sleep [DMS]/early morning awakening [EMA], and excessive daytime sleepiness [EDS]). Data were prospectively collected at four time points (spring, summer, fall, and winter).

Results

Seasonal changes in sleep duration were found, with the longest in winter and the shortest in summer (winter–summer difference: 0.19 h). The seasonality of sleep duration was influenced by age, sex, and residential area. In terms of age, seasonal changes in sleep duration were found in the middle and old age groups, but not in the young age group. Seasonal changes in the frequencies of sleep problems were found for some items in the young age group (DMS/EMA and EDS) and middle age group (DIS and DMS/EMA); however, no such changes were observed in the old age group.

Conclusion

Seasonal effects on sleep and sleep problems were found in Japanese community residents, but these varied between age groups. Furthermore, seasonal changes in sleep duration were influenced by sex and residential area.

Blue light filtered white light induces depression-like responses and temporary spatial learning deficits in rats

OBJECTIVES

Ambient light has a vital impact on mood and cognitive functions. Blue light has been previously reported to play a salient role in the antidepressant effect via melanopsin. Whether blue light filtered white light (BFW) affects mood and cognitive functions remains unclear. The present study aimed to investigate whether BFW led to depression-like symptoms and cognitive deficits including spatial learning and memory abilities in rats, and whether they were associated with the light-responsive function in retinal explants.

METHODS

Male Sprague-Dawley albino rats were randomly divided into 2 groups (n = 10) and treated with a white light-emitting diode (LED) light source and BFW light source, respectively, under a standard 12 : 12 h L/D condition over 30 days. The sucrose consumption test, forced swim test (FST) and the level of plasma corticosterone (CORT) were employed to evaluate depression-like symptoms in rats. Cognitive functions were assessed by the Morris water maze (MWM) test. A multi-electrode array (MEA) system was utilized to measure electro-retinogram (ERG) responses induced by white or BFW flashes.

RESULTS

The effect of BFW over 30 days on depression-like responses in rats was indicated by decreased sucrose consumption in the sucrose consumption test, an increased immobility time in the FST and an elevated level of plasma CORT. BFW led to temporary spatial learning deficits in rats, which was evidenced by prolonged escape latency and swimming distances in the spatial navigation test. However, no changes were observed in the short memory ability of rats treated with BFW. The micro-ERG results showed a delayed implicit time and reduced amplitudes evoked by BFW flashes compared to the white flash group.

CONCLUSIONS

BFW induces depression-like symptoms and temporary spatial learning deficits in rats, which might be closely related to the impairment of light-evoked output signals in the retina.

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.

Annual variation in daily light exposure and circadian change of melatonin and cortisol concentrations at a northern latitude with large seasonal differences in photoperiod length

Background

Seasonal variations in physiology and behavior have frequently been reported. Light is the major zeitgeber for synchronizing internal circadian rhythms with the external solar day. Non-image forming effects of light radiation, for example, phase resetting of the circadian rhythms, melatonin suppression, and acute alerting effects, depend on several characteristics of the light exposure including intensity, timing and duration, spectral composition and previous light exposure, or light history. The aim of the present study was to report on the natural pattern of diurnal and seasonal light exposure and to examine seasonal variations in the circadian change of melatonin and cortisol concentrations for a group of Swedish office workers.

Methods

Fifteen subjects participated in a field study that was carried out in the south of Sweden. Ambulatory equipment was used for monthly measurements of the daily exposure to light radiation across the year. The measurements included illuminance and irradiance. The subjects collected saliva samples every 4 h during 1 day of the monthly measuring period.

Results

The results showed that there were large seasonal differences in daily amount of light exposure across the year. Seasonal differences were observed during the time periods 04:00–08:00, 08:00–12:00, 12:00–16:00, 16:00–20:00, and 20:00–24:00. Moreover, there were seasonal differences regarding the exposure pattern. The subjects were to a larger extent exposed to light in the afternoon/evening in the summer. During the winter, spring, and autumn, the subjects received much of the daily light exposure in the morning and early afternoon. Regarding melatonin, a seasonal variation was observed with a larger peak level during the winter and higher levels in the morning at 07:00.

Conclusions

This study adds to the results from other naturalistic studies by reporting on the diurnal and seasonal light exposure patterns for a group living at a northern latitude of 56° N, with large annual variations in photoperiod length. It seems to be seasonal variation in the lighting conditions, both concerning intensities as well as regarding the pattern of the light exposure to which people living at high latitudes are exposed which may result in seasonal variation in the circadian profile of melatonin.

Light therapy and serotonin transporter binding in the anterior cingulate and prefrontal cortex

OBJECTIVE

To investigate the effects of light therapy on serotonin transporter binding (5-HTT BPND ), an index of 5-HTT levels, in the anterior cingulate and prefrontal cortices (ACC and PFC) of healthy individuals during the fall and winter. Twenty-five per cent of healthy individuals experience seasonal mood changes that affect functioning. 5-HTT BPND has been found to be higher across multiple brain regions in the fall and winter relative to spring and summer, and elevated 5-HTT BPND may lead to extracellular serotonin loss and low mood. We hypothesized that, during the fall and winter, light therapy would reduce 5-HTT BPND in the ACC and PFC, which sample brain regions involved in mood regulation.

METHOD

In a single-blind, placebo-controlled, counterbalanced, crossover design, [(11) C]DASB positron emission tomography was used measure 5-HTT BPND following light therapy and placebo conditions during fall and winter.

RESULTS

In winter, light therapy significantly decreased 5-HTT BPND by 12% in the ACC relative to placebo (F1,9 = 18.04, P = 0.002). In the fall, no significant change in 5-HTT BPND was found in any region across conditions.

CONCLUSION

These results identify, for the first time, a central biomarker associated with the intervention of light therapy in humans which may be applied to further develop this treatment for prevention of seasonal depression.

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.

Geographical and climatic factors and depression risk in the SUN project

BACKGROUND

Depression incidence has been related with seasonal periodicity and climate. The aim of the study was to estimate the possible association between depression and specific meteorological factors, namely temperature, light and rain.

METHODS

In total, 13,938 participants from the SUN (Seguimiento Universidad de Navarra) cohort study were included in the analysis. Subjects were classified according to daily mean temperature, number of daylight hours and amount of rain, by year, at their geographical area of residence, data supplied by the Spanish Agency of Meteorology. Participants were considered as incident cases of depression whenever they reported a physician diagnosis of depression or the use of antidepressant medication in any of the follow-up questionnaires. Cox regression models were fit to assess the relationship between climatic and geographical factors and the incidence of depression.

RESULTS

Male subjects living in the south and centre areas of Spain showed a higher risk to develop depression compared with those living in the north area (hazard ratio = 1.6, 95% CI = 1.16-2.23 and hazard ratio = 1.41, 95% CI = 1.06-1.87, respectively). Moreover, among males, a direct association between the number of daily light hours and mean temperature and the risk of depression was also found. For men, living in rainy areas was associated with a lower risk of developing depression.

CONCLUSION

Our results suggest that climate-depression relationship is more complex than previously thought, and strongly different between men and women.

Seasonal changes in gene expression represent cell-type composition in whole blood

Seasonal patterns in behavior and biological parameters are widespread. Here, we examined seasonal changes in whole blood gene expression profiles of 233 healthy subjects. Using weighted gene co-expression network analysis, we identified three co-expression modules showing circannual patterns. Enrichment analysis suggested that this signal stems primarily from red blood cells and blood platelets. Indeed, a large clinical database with 51 142 observations of blood cell counts over 3 years confirmed a corresponding seasonal pattern of counts of red blood cells, reticulocytes and platelets. We found no direct evidence that these changes are linked to genes known to be key players in regulating immune function or circadian rhythm. It is likely, however, that these seasonal changes in cell counts and gene expression profiles in whole blood represent biological and clinical relevant phenomena. Moreover, our findings highlight possible confounding factors relevant to the study of gene expression profiles in subjects collected at geographical locations with disparaging seasonality patterns.

Railway suicide attempts are associated with amount of sunlight in recent days

BACKGROUND

To assess the relationship between hours of sunlight and railway suicide attempts, 3-7 days before these attempts.

METHODS

All railway suicide attempts causing railway suspensions or delays of 30 min or more between 2002 and 2006. We used a linear probability model to assess this relationship. This study was conducted at Tokyo, Kanagawa, and Osaka prefectures in Japan. Data were collected from the railway delay incident database of the Japanese Railway Technical Research Institute and public weather database of the Japan Meteorological Agency.

RESULTS

About 971 railway suicides attempts occurred between 2002 and 2006 in Tokyo, Kanagawa, and Osaka. Less sunlight in the 7 days leading up to the railway suicide attempts was associated with a higher proportion of attempts (p=0.0243). Sunlight over the 3 days before an attempt had a similar trend (p=0.0888). No difference was found in sunlight hours between the days with (median: 5.6 [IQR: 1.1-8.8]) and without (median: 5.7 [IQR: 1.0-8.9]) railway suicide attempts in the evening. Finally, there was no apparent correlation between the railway suicide attempts and the monthly average sunlight hours of the attempted month or those of a month before.

LIMITATIONS

Railway suicides were not the main suicidal methods in Japan,

CONCLUSIONS

We observed an increased proportion of railway suicide attempts after several days without sunlight. Light exposure (blue light or bright white light) in trains may be useful in reducing railway suicides, especially when consecutive days without sunshine are forecasted.

Ornithine ingestion improved sleep disturbances but was not associated with correction of blood tryptophan ratio in Japanese Antarctica expedition members during summer

Members of expeditions to Antarctica may show changes in biological and physiological parameters involved in lipid, glucose, and thyroid hormone metabolism as they adapt to the environment; however, alterations in amino acid (AA) levels and sleep among expedition members in Antarctica have yet to be fully elucidated. We hypothesized that there would be alterations of blood AA levels, and ornithine (Orn) ingestion would affect biological parameters and sleep in Japanese expedition members during the summer in Antarctica. Japanese Antarctica Research Expedition members (22 people) who stayed in Antarctica for 3 months from December 2010 were examined, and a randomized double-blind study of Orn ingestion (400 mg/d) for 4 weeks was performed. Sleep conditions were evaluated subjectively by the Oguri-Shirakawa-Azumi (brief version) questionnaire. The blood of Japanese Antarctica Research Expedition members in Antarctica showed higher creatine kinase, lactate dehydrogenase, and ammonia levels than that in Japan. On blood AA analysis, aspartate, Orn, and serine were significantly higher, and alanine and tryptophan (Trp) were significantly lower in Antarctica than in Japan. The Trp ratio, the value of Trp divided by the sum of phenylalanine, tyrosine, and branched-chain AAs, was significantly lower in Antarctica than in Japan. Although sleep deteriorated during the stay in Antarctica, Orn ingestion, to some extent, improved sleep compared with the placebo group in Antarctica, suggesting that Orn is effective for people with heavy physical workloads in places such as Antarctica.

Melanopsin gene polymorphism I394T is associated with pupillary light responses in a dose-dependent manner

BACKGROUND

Melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) play an important role in non-image forming responses to light, such as circadian photoentrainment, light-induced melatonin suppression, and pupillary light response. Although it is known that there are some single nucleotide polymorphisms (SNPs) in the melanopsin (OPN4) gene in humans, the associations of the SNPs with non-image forming responses to light remains unclear. In the present study, we examined the associations of melanopsin gene polymorphisms with pupillary light response.

METHODS

Japanese university students (mean age: 21.0 ± 1.7 years) with the genotypes of TT (n = 38), TC (n = 28) and CC (n = 7) at rs1079610 (I394T) located in the coding region participated in the present study. They were matched by age and sex ratio. Dark-adapted pupil size (<1 lx) was first measured. Then steady-state pupil size was measured during exposure to five lighting conditions (10 lx, 100 lx, 1000 lx, 3000 lx, 6000 lx in the vertical direction at eye level).

RESULTS

Significant interaction between the genotype of I394T (TT versus TC+CC) and luminance levels was found in pupil size. Under high illuminance levels (1000 lx, 3000 lx and 6000 lx), pupil sizes in subjects with the C allele were significantly smaller than those in subjects with the TT genotype. On the other hand, pupil size in subjects with the C allele under low illuminance (<1 lx) was significantly larger than that in subjects with the TT genotype. Percentages of pupil constriction under high illuminance levels were significantly greater in subjects with the C allele than in subjects with the TT genotype.

CONCLUSIONS

Human melanopsin gene polymorphism I394T interacted with irradiance in association with pupil size. This is the first evidence suggesting a functional connection between melanopsin gene polymorphism and pupillary light response as an index of non-image forming response to light.

Intra-regional assortative sociality may be better explained by social network dynamics rather than pathogen risk avoidance

Fincher & Thornhill's (F&T's) model is not entirely supported by common patterns of affect behaviors among people who live under varying climatic conditions and among people who endorse varying levels of (Western) religiosity and conservative political ideals. The authors' model is also unable to account for intra-regional heterogeneity in assortative sociality, which, we argue, can be better explained by a framework that emphasizes the differential expression of fundamental social cues for maintaining distinct social network structures.

No effects of acclimation to heat on immune and hormonal responses to passive heating in healthy volunteers

Heat acclimation results in whole body-adaptations that increase heat tolerance, and might also result in changed immune responses. We hypothesized that, after heat acclimation, tumor necrosis factor alpha, interleukin 6 and the lymphocyte count would be altered. Heat acclimation was induced in 6 healthy men by 100 min of heat exposure for 9 days. Heat exposure consisted of (1) 10 min of immersion up to chest-level in water at 42°C and (2) 90 min of passive heating by a warm blanket to maintain tympanic temperature at 37.5°C. The climatic chamber was maintained at 40°C and a relative humidity of 50%. Blood samples were analyzed before and after heat acclimation for natural killer (NK) cell activity, counts of lymphocytes B and T, before and after heat acclimation for peripheral blood morphology, interleukin 6, tumor necrosis factor alpha, and cortisol. A Japanese version of the profile of mood states questionnaire was also administered before and after acclimation. The concentrations of white blood cells, lymphocytes B and T, cortisol, interleukin 6, tumor necrosis factor alpha and NK cell activity showed no significant differences between pre- and post-acclimation, but there was a significantly lower platelet count after acclimation and, with the profile of mood states questionnaire, there was a significant rise in anger after acclimation. It is concluded that heat acclimation by passive heating does not induce alterations in immune or endocrine responses.

Bright-light therapy in the treatment of mood disorders

Bright-light therapy (BLT) is established as the treatment of choice for seasonal affective disorder/winter type (SAD). In the last two decades, the use of BLT has expanded beyond SAD: there is evidence for efficacy in chronic depression, antepartum depression, premenstrual depression, bipolar depression and disturbances of the sleep-wake cycle. Data on the usefulness of BLT in non-seasonal depression are promising; however, further systematic studies are still warranted. In this review, the authors present a comprehensive overview of the literature on BLT in mood disorders. The first part elucidates the neurobiology of circadian and seasonal adaptive mechanisms focusing on the suprachiasmatic nucleus (SCN), the indolamines melatonin and serotonin, and the chronobiology of mood disorders. The SCN is the primary oscillator in humans. Indolamines are known to transduce light signals into cells and organisms since early in evolution, and their role in signalling change of season is still preserved in humans: melatonin is synthesized primarily in the pineal gland and is the central hormone for internal clock circuitries. The melatonin precursor serotonin is known to modulate many behaviours that vary with season. The second part discusses the pathophysiology and clinical specifiers of SAD, which can be seen as a model disorder for chronobiological disturbances and the mechanism of action of BLT. In the third part, the mode of action, application, efficacy, tolerability and safety of BLT in SAD and other mood disorders are explored.

Climatic relationships with specific clinical subtypes of depression

Studies on the relationship between climate and unipolar depression rates have yielded mixed results, which could be attributed to the inclusion of heterogeneous clinical samples and the use of admission rather than onset dates. This study aimed to overcome these methodological issues. During an 8-year timeframe, onset rates of unipolar depressive episodes requiring hospitalization from individuals living up to 15 km from a selected meteorological station were stratified by clinical subtypes and modeled as Autoregressive Integrated Moving Average (ARIMA) functions of orthogonal climatic factors obtained by Principal Components Analysis (PCA). For comparison purposes, onset rates stratified by demographic factors and by diagnosis of Seasonal Affective Disorder (SAD) and admission rates were also modeled. The main findings were a negative 1-month delayed relationship between onset rates of episodes with melancholic features and a climatic factor mainly composed of ambient temperature/sunlight, and a negative 1-month delayed relationship between onset rates of episodes with psychotic features and a climatic factor mainly composed of barometric pressure. Results of this study support a climatic-rather than seasonal-influence in specific subtypes of depression. If replicated, they may have nosological and therapeutic implications.

Seasonal variation in the incidence of gastroesophageal reflux disease

BACKGROUND

To examine the seasonal variation in the incidence of gastroesophageal reflux disease (GERD) for different gender and age groups and its association with climatic parameters (ambient temperature, relative humidity, atmospheric pressure, rainfall, and hours of sunshine).

METHODS

A total of 76,636 ambulatory care visits for the treatment of GERD between 2001 and 2006 were included. Monthly GERD incidence rates per 10,000 people were calculated over 72 months and categorized by gender and age groupings (19-44, 45-64, and >or=65 years). Seasonality is a general component of time-series patterns. The auto-regressive integrated moving average (ARIMA) regression method was used to evaluate the effects of climatic and monthly factors on GERD incidence rates after adjusting for the time-trend effect.

RESULTS

Seasonal trends showed an incidence peak in October to December, followed by a sharp decrease in January, and a trough in February; a fairly similar seasonal pattern of GERD incidence was apparent for gender, age, and combined groups. The ARIMA test for seasonality found a significant association for the total group (P < 0.01), for female (P < 0.05) patients, and for the 45 to 64 years (P < 0.01) and >64 years (P < 0.01) age groups. The ARIMA models also showed that relative humidity was negatively related to monthly GERD incidence rates for men (P < 0.01) and the >64 years (P < 0.01) age group.

CONCLUSION

Data showed seasonal variations in GERD incidence. Relative humidity was associated with monthly GERD incidence rates for men and the >64 years age group.

Seasonal variation in blood concentrations of interleukin-6, adrenocorticotrophic hormone, metabolites of catecholamine and cortisol in healthy volunteers

We investigated seasonal changes in blood concentrations of interleukin-6 (IL-6), adrenocorticotrophic hormone (ACTH), metabolites of catecholamine (VMA, HVA, and 5-HIAA) and cortisol in humans. Eight volunteers were investigated at four times during the year (February, May, August and October) at latitude 35 degrees N. The mean ambient temperature at the collection periods was higher in the order of summer > autumn approximately spring > winter. Changes in mood were also monitored by a profile of mood states (POMS) questionnaire. The concentration of IL-6 was significantly higher in winter and summer than in spring and autumn. The concentrations of ACTH, HVA and VMA were significantly higher in summer. No seasonal variation was detected in cortisol. There were significant differences among the seasons in subscale tension and anger in the POMS questionnaire; the tension subscale showed significant differences between spring and autumn, with a higher score in spring. The results demonstrate that Il-6, ACTH, HVA and VMA exhibit statistically significant seasonal rhythms, which might have important diagnostic and therapeutic implications.

A socio-relational framework of sex differences in the expression of emotion

Despite a staggering body of research demonstrating sex differences in expressed emotion, very few theoretical models (evolutionary or non-evolutionary) offer a critical examination of the adaptive nature of such differences. From the perspective of a socio-relational framework, emotive behaviors evolved to promote the attraction and aversion of different types of relationships by advertising the two most parsimonious properties of reciprocity potential, or perceived attractiveness as a prospective social partner. These are the individual's (a) perceived capacity or ability to provide expedient resources, or to inflict immediate harm onto others, and their (b) perceived trustworthiness or probability of actually reciprocating altruism (Vigil 2007). Depending on the unique social demands and relational constraints that each sex evolved, individuals should be sensitive to advertise "capacity" and "trustworthiness" cues through selective displays of dominant versus submissive and masculine versus feminine emotive behaviors, respectively. In this article, I introduce the basic theoretical assumptions and hypotheses of the framework, and show how the models provide a solid scaffold with which to begin to interpret common sex differences in the emotional development literature. I conclude by describing how the framework can be used to predict condition-based and situation-based variation in affect and other forms of expressive behaviors.

Less Exposure to Daily Ambient Light in Winter Increases Sensitivity of Melatonin to Light Suppression

This study was carried out to examine the seasonal difference in the magnitude of the suppression of melatonin secretion induced by exposure to light in the late evening. The study was carried out in Akita (39 degrees North, 140 degrees East), in the northern part of Japan, where the duration of sunshine in winter is the shortest. Ten healthy male university students (mean age: 21.9+/-1.2 yrs) volunteered to participate twice in the study in winter (from January to February) and summer (from June to July) 2004. According to Japanese meteorological data, the duration of sunshine in Akita in the winter (50.5 h/month) is approximately one-third of that in summer (159.7 h/month). Beginning one week prior to the start of the experiment, the level of daily ambient light to which each subject was exposed was recorded every minute using a small light sensor that was attached to the subject's wrist. In the first experiment, saliva samples were collected every hour over a period of 24 h in a dark experimental room (<15 lux) to determine peak salivary melatonin concentration. The second experiment was conducted after the first experiment to determine the percentage of melatonin suppression induced by exposure to light. The starting time of exposure to light was set 2 h before the time of peak salivary melatonin concentration detected in the first experiment. The subjects were exposed to light (1000 lux) for 2 h using white fluorescent lamps (4200 K). The percentage of suppression of melatonin by light was calculated on the basis of the melatonin concentration determined before the start of exposure to light. The percentage of suppression of melatonin 2 h after the start of exposure to light was significantly greater in winter (66.6+/-18.4%) than summer (37.2+/-33.2%), p<0.01). The integrated level of daily ambient light from rising time to bedtime in summer was approximately twice that in winter. The results suggest that the increase in suppression of melatonin by light in winter is caused by less exposure to daily ambient light.

The cortisol awakening response, seasonality, stress and arousal: a study of trait and state influences

The aim of this study was to investigate the relationship between the cortisol awakening response (CAR) and two key state variables (morning stress and arousal) and the trait-like variable of seasonality as recent evidence suggests that the CAR is subject to both state and trait influences. The CAR was examined across two consecutive winter days in 50 healthy participants. Participants collected saliva samples in the domestic setting immediately on awakening, then at 15, 30 and 45min post-awakening on the two study days. Concomitant trait and state measures were examined, notably seasonal changeability in mood as a trait, and self-reported stress and arousal as state measures. Although there was correlational stability for measures of the CAR across days, there was a significant difference in the magnitude of the increase in cortisol levels following awakening between the two study days, being greater on the first sampling day. This reduction in the magnitude of cortisol increase was significantly associated with an observed reduction across the 2 days in self-reported arousal assessed at 45min following awakening. Participants reported greater arousal (more alert, active, energetic and stimulated, less drowsy, tired and sluggish) on the first study day than the second. Average CAR across days was associated with seasonality score, greater propensity for seasonal changes in mood being associated with smaller average CAR. High seasonality scorers were also more likely as a group to show a strong association between daily changes in state arousal and CAR. This study supports the view that the CAR is, in part, susceptible to short-term changes in state variables, notably perceived arousal, while observing a novel link between CAR and the trait variable of perceived seasonality. Finally a tentative finding suggests the importance of examining for possible interaction between trait and state effects, evidenced by a significantly greater association between state arousal changes and cortisol response changes in those with high (trait) seasonality.

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

BACKGROUND

Prior studies identified a seasonal pattern in symptoms of depression in clinical and population-based samples. The aims of our study were to estimate the prevalence rates of routine seasonal variations in mood and behavior and of current depressive symptoms in the Finnish general population over 30 years, and to find differences, if any, between the northern and southern regions of residence.

METHODS

5749 participants aged 30-97 (3156 women and 2593 men) were interviewed face to face and attended a health status examination. We included the modified Seasonal Pattern Assessment Questionnaire and the modified Beck Depression Inventory (BDI) for the analysis.

RESULTS

85% of the sample, representative of a general population, had seasonal variations in mood and behavior; 9% of the sample scored high on both scales, thus having the routine seasonal variations together with a current self-report of winter depression. Scoring high on the former scale yielded the odds ratio of 3.12 for scoring high on the BDI. Neither the global seasonality score nor the BDI sum score was associated with latitude. No significant differences in affective symptoms were found by the latitude. The seasonal variation in sleep duration (P<0.001) was more prevalent in the northern regions.

LIMITATIONS

The seasonal variations were assessed with a self-report only.

CONCLUSIONS

A seasonal pattern in mood and behaviors was detected in a general population. Implications of our findings include the assessment of the seasonal variations as a risk factor of depressive illness.

A Theory of the Emergence, Persistence, and Expression of Geographic Variation in Psychological Characteristics

Volumes of research show that people in different geographic regions differ psychologically. Most of that work converges on the conclusion that there are geographic differences in personality and values, but little attention has been paid to developing an integrative account of how those differences emerge, persist, and become expressed at the geographic level. Drawing from research in psychology and other social sciences, we present a theoretical account of the mechanisms through which geographic variation in psychological characteristics emerge and persist within regions, and we propose a model for conceptualizing the processes through which such characteristics become expressed in geographic social indicators. The proposed processes were examined in the context of theory and research on personality traits. Hypotheses derived from the model were tested using personality data from over half a million U.S. residents. Results provided preliminary support for the model, revealing clear patterns of regional variation across the U.S. and strong relationships between state-level personality and geographic indicators of crime, social capital, religiosity, political values, employment, and health. Overall, this work highlights the potential insights generated by including macrolevel perspectives within psychology and suggests new routes to bridging theory and research across several disciplines in the social sciences.

Monthly variation in prevalence rates of comorbid depression and anxiety in the general population at 63-65 degrees North: the HUNT study

BACKGROUND

To investigate monthly variation in depression, anxiety and their comorbidity (COM) in an epidemiologic study and their association to monthly variation in suicide rates.

METHODS

60,995 participants of the Health Study of Nord-Trøndelag County in 1995-97 rated themselves on the Hospital Anxiety and Depression Scale (HADS) in all months except July. All 10,670 male and 3833 female suicides in Norway from 1969 through 1996 were included.

RESULTS

The prevalence of comorbid anxiety and depression was highest in spring (April, May) and in October (p<0.01). There was a correlation between the monthly variation in the national suicide rate and monthly variation in comorbid anxiety and depression (r=0.72, df=11, p=0.01) and for male alone (r=0.67, df=11, p=0.03). There was also a significant monthly variation in the prevalence of depression (p<0.001) and no monthly variation in the prevalence of anxiety.

LIMITATIONS

Limited information about the third of the population who did not take part in the HUNT-2 Study. HADS based depression and anxiety cover psychological symptoms, not somatic and social ones. In relation to DSM-IV and ICD-10 defined anxiety disorders and depressions, the sensitivity and specificity of HADS caseness, give a considerable number of false-positive cases.

CONCLUSIONS

Increased prevalence of comorbid depression and anxiety in males during spring, and its association with suicidality should have clinical importance, as identification and treatment could influence suicide rates.

Sensitivity to seasonal changes in panic disorder patients

It has been suggested that symptoms of panic disorder may be significantly affected by seasonal factors including weather changes, although few studies have explored the issue. The purpose of the present paper was to investigate clinical data to examine sensitivity of panic disorder patients to seasonal changes and seasonal fluctuation of panic disorder symptoms. A self-rating questionnaire consisting of the Seasonal Pattern Assessment Questionnaire (SPAQ) and additional self-rating questions were analyzed in 146 Japanese patients (50 male, 96 female) with panic disorder (DSM-IV) at an outpatient clinic for anxiety disorder. The average of the Global Seasonality Scores (GSS) was 12.5+/-4.7 and 25.3% of the patients were suggested to suffer from seasonal affective disorder, according to the GSS. Frequency of the panic attack was found to fluctuate seasonally, with peaks in August and December (P=0.005 and 0.01, chi2 test). The present results indicate that panic disorder patients may be more sensitive to seasonal and meteorological factors than the general population and become more fragile in a specific season or months. This might assist in the development of preventive measures for the frequent recurrence of symptoms in panic disorder.

High prevalence of self-reported winter depression in a Swedish county

The prevalence of winter depression was unknown in Sweden, therefore prevalence figures of seasonal affective disorder (SAD) and subsyndromal SAD (S-SAD) were estimated. Age and gender differences, prevalence in the group of non-responders and some psychometric qualities of the Seasonal Pattern Assessment Questionnaire (SPAQ) were calculated. A modified version of the SPAQ was sent to a random sample of 2500 persons (response rate 66.3%, n=1657) between 18 and 64 years residing in Dalarna, a county in central Sweden. The sample was proportionally stratified according to age, gender and home municipality. The prevalence of winter SAD was estimated at 8% and S-SAD at 10.8%. It was approximately twice as common among women and younger persons. A total of 3.1% reported seasonal problems to be severe or disabling and 19.3% that everyday life was negatively affected. Experiencing seasonally changing depressive symptoms was common in the population. Factor analysis of the Global Seasonal Score resulted in one factor and the internal consistency was 0.88 (Cronbach's alpha). The results indicate that self-reported recurrent depression during winter is common in Sweden and should therefore receive more attention from health care authorities.

The diagnosis, symptomatology, and epidemiology of seasonal affective disorder

The operational criteria for seasonal affective disorder (SAD) have undergone several changes since first proposed in 1984. SAD is currently included as a specifier of either bipolar or recurrent major depressive disorder in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. The International Classification of Diseases, Tenth Edition has provisional diagnostic criteria for SAD. The most characteristic quality of SAD is that the symptoms usually present during winter and remit in the spring. Furthermore, the symptoms tend to remit when the patients are exposed to daylight or bright light therapy. The cognitive and emotional symptoms are as in other types of depression but the vegetative symptoms are the reverse of classic depressive vegetative symptoms, namely increased sleep and increased appetite. SAD is a common condition, but the exact prevalence rates vary between different studies and countries and is consistently found to be more common in women and in youth. SAD probably possibly occurs in children although not as commonly as in young adults. Some studies have found that certain ethnic groups who live at high northern latitudes may have adapted to the long arctic winter.

A help-line for children. Seasonal variations in issues

The objectives of the study were to describe monthly variations in issues in calls to a help-line for children and adolescents. All 80,983 calls to a Red Cross Help-Line for children in 1991-1997 were included. In 22,698 calls, information about age, sex or issue could be identified. A monthly variation in frequency of calls with peaks in April and November and a correlation with the absolute values of monthly changes in length of day were found. Conversations concerning psychiatric suffering were more frequent in January or February and less frequent than expected in May/June and December. Conversations about sexuality correlated with the frequencies of births in the adult population 9 months later. A spring and fall peak in total calling and a winter peak in calls for depression, anxiety, pain and neglect were described.

Seasonal variation in postnatal depression

BACKGROUND

We evaluated the occurrence of postnatal depression in general and during different seasons as part of a larger longitudinal mother-child follow-up study.

METHOD

One hundred and eighty-five mothers, from the maternity wards of University Hospital of Oulu, Finland, completed a self-rating depression scale, the Edinburgh Postnatal Depression Scale (EPDS) twice: first at hospital 2-7 days after delivery and the second time at home 4 months after the delivery. Different psychosocial variables were mapped out to avoid any confounding factors. The year was divided in two separate ways: first, three different time periods were selected by the amount of sunlight: dark (October-January), intermediate (February, March, August, September) and light (April-July), and second, the year was divided by seasons. The results were analysed by the chi(2)-test for multinomials.

RESULTS

Sixteen percent (16.2) of mothers were scored as being depressed using 13 as a cut-off point immediately after the infant was born. Thirteen percent (13.0) were depressed measured 4 months postpartum. There was more mild depression in the autumn (ratio observed/expected 1,62; 95% confidence interval 1.05-2.19) immediately after delivery, using 10 as a cut-off, and less depression in the spring (0.27; 0.00-0.62) measured at home later, using 13 as a cut-off. When using classification by the amount of light there was more depression during the dark time (1.58; 1.05-2.11) immediately postpartum.

LIMITATIONS

The group sizes and the amount of sample sizes collected within each month are quite small.

CONCLUSIONS

It should be borne in mind that seasonal changes and alterations in the amount of light might influence the occurrence of postnatal depression.

Cross-regional survey of seasonal affective disorders in adults and high-school students in Japan

BACKGROUND

In Asian countries, there is no epidemiological report on seasonal affective disorder (SAD) in different age groups and different geographic regions surveyed at the same time. The aim of this study was to estimate the prevalence rates of SAD and risk factors for SAD in adults and high-school students, with special reference to the difference of winter SAD between northern and southern regions in Japan.

METHODS

A total of 3237 high-school students and 4858 workers living in Japan (31.3-43.5 degrees N) responded to this epidemiological survey using Japanese version of the Seasonal Pattern Assessment Questionnaire (SPAQ).

RESULTS

The overall prevalence rates of winter SAD (subsyndromal winter SAD) and summer SAD (subsyndromal summer SAD) in high-school students were 0.91(2.21) and 0.81(2.57)%, respectively. In workers, these rates were 0.45(1.16) and 0.43(0.71)%, respectively. Although no regional difference was noted in high-school students with winter seasonal type, the estimated odds ratio of this type for northern workers was nearly 3-fold higher than the southern counterparts. The prevalence rates of each seasonal type were not significantly different between two sexes in both age groups. No clear dependence on latitude was seen with regard to summer SAD in both age groups.

LIMITATIONS

The effect of climate on SAD could not be entirely excluded from geophysical factor as indexed by latitude.

CONCLUSIONS

SAD was less common in adults than in high-school students. While latitude was a major determinant of winter type in adults, socio-cultural factors or other contributing factors might affect the development of this type in high-school students.

Seasonal variation in suicides and in admissions to hospital for mania and depression

BACKGROUND

The influence of seasons on mood disorders is controversial.

OBJECTIVE

To examine monthly variations in admissions for mania and depressions including variations with sex and age and correlations with frequencies of suicides.

METHODS

All admissions for mania or depression (N=4341) in a population of 1,800,000 with 35,285 admissions in the years 1992-1996 were analysed. All 14,503 suicides in Norway the years 1969-1996 were also analysed.

RESULTS

Admissions for depression had a significant monthly variation for women (chi(2)=29.78, df=11, P<0.005) with the highest peak in November and for men (chi(2)=19.69, df=11, P<0.05) with the highest peak in April. Among women increasing age correlated negatively with the range of monthly observed/expected ratios (r(s)=-0.943, N=6, P<0.01) and with a of maximal monthly observed/expected ratio (r(s)=-0.943, N=6, P<0.01). Among men suicides correlated with admissions for depression (r=0.647, N=12, P<0.05) and mania (r=0.678, N=12, P<0.05).

LIMITATIONS

The time of admission to hospital are not identical to onset of affective episode. The study was done retrospectively. No sociocultural or physical environmental data were investigated.

CONCLUSION

A hypothesis of an influence of seasons on mood disorders is supported. Younger women seem to be especially vulnerable.

Seasonal affective disorder in an Arctic community

OBJECTIVE

To determine the rate of seasonal-pattern depression in an Inuit community above 70 degrees N.

METHOD

One-hundred and eleven people from randomly selected households were surveyed for depression and anxiety and the effect of the seasons on their mood. Eighty-eight people provided replies on the influence of the seasons.

RESULTS

One in five (22.6%) of the community sample was found to be depressed. Of these, seven (6.3%) had seasonal affective disorder (SAD), with fall onset occurring in six of these (5.4%). Subsyndromal SAD (SSAD) occurred in 11.7%, while any effect of the seasons (seasonality) occurred in 39.6%. Persons with SSAD and seasonality were significantly older than those unaffected by the seasonal effect. No other significant correlation of SAD, SSAD, or seasonality occurred with gender, age, and language preference.

CONCLUSION

Seasonal mood changes in this Inuit group living in the Canadian Arctic are elevated above the rates found in other studies using similar survey methods.

Seasonality, social zeitgebers and mood variability in entrainment of mood. Implications for seasonal affective disorder

BACKGROUND

Seasonal variations in mood (seasonality) appear to be entrained to light, a physical zeitgeber. We hypothesised that people high in seasonality may be responsive to a range of zeitgebers, because of greater mood variability. We investigated whether the moods of people high in seasonality were more strongly entrained to the calendar week, a social zeitgeber, and whether any such effect was dependent on variability of mood.

METHODS

53 participants (14 male, 39 female; overall mean age=30) completed a daily mood report, over 56 consecutive days. Participants also completed the Seasonality Score Index (SSI) of the Seasonal Pattern Assessment Questionnaire. Each participant's time series of daily mood was analysed by spectral analysis to quantify the strength of their weekly mood cycle.

RESULTS

Participants with high SSI scores (> or =11) had significantly stronger weekly mood cycles than those with low SSI scores (<11), and significantly greater variability in mood. Covarying for mood variability reduced the difference between high and low SSI groups in mean strength of weekly mood cycle to non-significance.

LIMITATIONS

The time series of moods obtained was relatively short, and moods among high seasonal participants may have been affected by seasonal weather variability.

CONCLUSIONS

People high in seasonality appear to be more responsive to external zeitgebers, and this could be linked to their greater variability in mood. The integration of research on mood variability with research on SAD appears to be warranted.

Seasonal affective disorder among primary care attenders and a community sample in Aberdeen

BACKGROUND

There are no large published studies of the prevalence of seasonal affective disorder (SAD) among UK populations.

AIM

To determine the prevalence of SAD among patients attending a general practitioner (GP).

METHOD

Patients aged 16-64 consulting their GPs in Aberdeen during January were screened with the Seasonal Pattern Assessment Questionnaire (SPAQ). SPAQs were also mailed to 600 matched patients, who had not consulted their GP during January. Surgery attenders who fulfilled SPAQ criteria for SAD were invited for interview to determine whether they met criteria for SAD in DSM-IV and the Structured Interview Guide for the Hamilton Rating Scale for Depression--Seasonal Affective Disorder Version (SIGH-SAD).

RESULTS

Of 6161 surgery attenders, 4557 (74%) completed a SPAQ; 442 (9.7%) were SPAQ cases of SAD. Rate of caseness on the SPAQ did not differ between surgery attenders and non-attenders. Of 223 interviewed SPAQ cases of SAD, 91 (41%) also fulfilled DSM-IV and SIGH-SAD criteria.

CONCLUSIONS

There is a high prevalence of SAD among patients attending their GPs in January in Aberdeen; this is likely to reflect a similar rate in the community.

Seasonal affective disorder and latitude: a review of the literature

BACKGROUND

The aim of the study is to investigate the relationship between the prevalence of SAD and latitude.

METHODS

An overview of the epidemiological literature on the prevalence of SAD is given and studies relevant for the latitudinal dependency of prevalence will be analyzed and discussed.

RESULTS

The mean prevalence of SAD is two times higher in North America compared to Europe. Over all prevalence studies, the correlation between prevalence and latitude was not significant. A significant positive correlation was found between prevalence and latitude in North America. For Europe there was a trend in the same direction.

CONCLUSIONS

The influence of latitude on prevalence seems to be small and other factors like climate, genetic vulnerability and social-cultural context can be expected to play a more important role. Additional controlled studies taking these factors into account are necessary to identify their influence.

Familial transmission of seasonal changes in sleep and eating function in the general population

Both genetic and environmental factors may be involved in the development of the increased sleep and appetite/body weight during winter, which are observed in seasonal affective disorder (SAD) as well as in normal variants of behavior in the general population. Decreases of these psychosomatic functions are also observed during summer, although the change may be less apparent than the winter changes. We studied familial correlation of these seasonal changes in 129 small Japanese families of the general population, using the Seasonality Pattern Assessment Questionnaire (SPAQ). No association was observed between the child and biological parents in the changes of sleep length or appetite/body weight during winter or summer. In contrast, significant spouse correlations were found in the changes of sleep and eating function during winter as well as during summer. This may indicate a role of shared environmental factors in the development of the seasonal patterns. The present results are preliminary and further studies are recommended.

Absence of seasonal variation in the phase of the endogenous circadian rhythm in humans

Humans may be subject to seasonal variations, as evidenced by the existence of seasonal affective disorder (SAD) and midwinter insomnia. However, some recent studies have shown that the seasonal variation in the phase of the circadian rhythm is relatively weak in healthy humans. In the present study, evidence is found that there is no seasonal variation in the phase of the endogenous circadian rhythm at all. Body temperature, cortisol excretion, and subjective alertness of six subjects recorded under constant routine conditions showed no systematic seasonal variation in circadian phases. This finding indicates that secondary zeitgebers blocked or counterbalanced the seasonal variation in the entrainment effect of the natural photoperiod. The human being may live in an environment in which the photoperiod has lost its status of primary zeitgeber.

Seasonal affective disorder: report from India (latitude 26 degrees 45'N)

BACKGROUND

A number of studies have established the entity of seasonal affective disorder (SAD) and delineated the presence of atypical depressive features of carbohydrate craving, hyperphagia and hypersomnia. Most literature has emanated from research carried out in temperate climates, and only few reports are available from tropical countries, especially India.

METHODS

Consecutive patients with recurrent mood disorder (who had at least 2 episodes of depression in the past) comprised the study sample. The diagnosis of mood disorder was made according to DSM-III-R criteria. The sample was divided into two groups - seasonal and non-seasonal according to the DSM-III-R criteria of seasonal pattern. The depressed patients were rated on SADD and HDRS, and manic patients on BRMRS.

RESULTS

Eighteen of 93 patients fulfilled the criteria of seasonal pattern; 7 of these seasonal patients, and 25 of the non-seasonal patients were currently in depressive phase. Males dominated the sample in both the groups. The seasonal and non-seasonal groups as regards symptomatology, differed only on a few items - decreased libido on SADD, and suicidal ideation and helplessness on HDRS. Atypical vegetative features were not seen in any of the seasonal patients.

CONCLUSIONS

SAD is seen at lower latitudes also, although atypical vegetative features are not a prominent part of the symptomatology.

LIMITATIONS

The study sampled was obtained from a very select population, and thus does not indicate the prevalence of SAD in India. Secondly, the small sample size precludes any categorical comments of the symptomatology. Moreover, winter and summer depressives were considered as one group.

CLINICAL RELEVANCE

Emphasising the presence of SAD in a tropical country where there is relatively less variation in daylight periods, this report forms a base for future studies. It also raises the question of the role of variations in daylight in the aetiology SAD.

Clinical characteristics of circadian rhythm sleep disorders

From our practice at the sleep disorders clinic in Kohnodai Hospital, National Center of Neurology and Psychiatry (NCNP), we report the clinical characteristics of circadian sleep-wake rhythm disorders. Nearly 90% of circadian rhythm sleep disorders were diagnosed as delayed sleep phase syndrome (DSPS) or as non-24 sleep-wake syndrome (non-24). While DSPS was equally common in males and females, non-24 was more frequently seen in men. It was of psychiatric interest that a considerable number of patients had depressive states in the course of their circadian rhythm sleep disorders. Difficulty in adapting to social life was more severe in patients with non-24 than in those with DSPS.

The influence of climate on suicidal behaviour in Italy

A growing number of studies report an asymmetry in the seasonal distribution of suicides, with a peak in the late spring months for both sexes. The aim of this study is to verify if the climate, apart from its seasonal change, exerts a direct influence on suicidal behaviour. To this end, deaths by suicide in 17 Italian towns which all have a meteorologic station have been analyzed, taking into account some climatic indicators. Results of analyses show an unequal distribution of suicides with respect to latitude, with a peak in the North. The distribution of deaths by suicide shows a negative relationship with mean yearly temperature values, max and min, and with sun exposure indicators, and a positive, but less significant relationship with rainfall values. As far as climatic variables considered as a whole are concerned, stepwise regression identifies three relevant factors with significant relationships to suicide rates: humidity grade, rainfall mean, and sunlight exposure. These three climatic indicators explain up to 63% (Adj R2) of the variance in the distribution of suicide rates for both genders, with sunlight exposure offering the most significant contribution, when regressed on suicide rates via a multiple regression model. Higher suicide rates, therefore, correspond to dry places which are less exposed to the sun. However, the variable which shows the most significant correlation with suicide rates for both sexes is not a climatic one, but the percentage of the population aged 65 and over. The distribution of people at greater biological risk for possible disruption of brain neurochemistry (i.e. older people), therefore, predicts the distribution of suicide rates. Climate contributes to this biological risk by modifying both the responsiveness of the circuits that control mood and behaviour, and also the frequency and intensity of social interaction.