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IMPORTANCE It has been observed that suicidal behavior is influenced by sunshine and follows a seasonal pattern. However, seasons bring about changes in several other meteorological factors and a seasonal rhythm in social behavior may also contribute to fluctuations in suicide rates. OBJECTIVE To investigate the effects of sunshine on suicide incidence that are independent of seasonal variation. DESIGN, SETTING, AND PARTICIPANTS Retrospective analysis of data on all officially confirmed suicides in Austria between January 1, 1970, and May 6, 2010 (n = 69 462). Data on the average duration of sunshine per day (in hours) were calculated from 86 representative meteorological stations. Daily number of suicides and daily duration of sunshine were differentiated to remove variation in sunshine and variation in suicide incidence introduced by season. Thereafter, several models based on Pearson correlation coefficients were calculated. MAIN OUTCOMES AND MEASURES Correlation of daily number of suicides and daily duration of sunshine after mathematically removing the effects of season. RESULTS Sunshine hours and number of suicides on every day from January 1, 1970, to May 6, 2010, were highly correlated (r = 0.4870; P < 10 −9). After differencing for the effects of season, a mathematical procedure that removes most of the variance from the data, a positive correlation between number of suicides and hours of daily sunshine remained for the day of suicide and up to 10 days prior to suicide (r maximum = 0.0370; P < 10 −5). There was a negative correlation between the number of suicides and daily hours of sunshine for the 14 to 60 days prior to the suicide event (r minimum = −0.0383; P < 10 −5). These effects were found in the entire sample and in violent suicides. CONCLUSIONS AND RELEVANCE Duration of daily sunshine was significantly correlated with suicide frequency independent of season, but effect sizes were low. Our data support the hypothesis that sunshine on the day of suicide and up to 10 days prior to suicide may facilitate suicide. More daily sunshine 14 to 60 days previously is associated with low rates of suicide. Our study also suggests that sunshine during this period may protect against suicide.

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Recent findings in basic scientific research, such as neurobiological and neuroimaging studies, have suggested common pathways for food and drug intake. It was hypothesized that both compete for the same brain reward sites, and that a higher body mass index (BMI) may be associated with lower substance use. The aim of this study was to investigate the relationship between BMI and substance use in a large sample of young male adults. The sample consisted of 1,902 18-year-old males from a province of Austria in a naturalistic cross-sectional setting. Questionnaires were administered to assess alcohol abuse and dependence (CAGE) and nicotine dependence (Heavy Smoking Index). Urine samples were collected to assess the prevalence of recent illicit drug use. Associations between BMI and substance use were calculated by means of logistic regression analyses. An inverse relationship between BMI and recent illicit drug use was found. This relationship remained significant after adjusting for possible confounding factors such as level of education, nicotine dependence, breath carbon monoxide (CO) levels, and alcohol abuse and dependence. No significant association was found between BMI and nicotine and alcohol dependence. A higher BMI was associated with lower illicit drug use in our sample of young adult males. These results provide further evidence for the hypothesis that food and drugs may compete for the same brain reward sites.

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BackgroundSeasonal changes and climatic factors like ambient temperature, sunlight duration and rainfall can influence suicidal behavior.MethodsThis study analyses the relationship between seasonal changes and climatic variations and suicide attempts in 2131 young patients in Istanbul, Turkey.ResultsIn our study sample, there was an association between suicide attempts in youths and seasonal changes, as suicide attempts occurred most frequently during summer in females as well as in males. Furthermore, there was a positive correlation between the mean temperature over the past 10 days and temperature at the index day and suicide attempts in females. After seasonality effects were mathematically removed, the mean temperature 10 days before a suicide attempt remained significant in males only, indicating a possible short-term influence of temperature on suicide attempts.ConclusionsThis study shows an association between suicide attempts of young people and climatic changes, in particular temperature changes as well as seasonal changes. Therefore, the influence of seasonal changes and climatic factors on young suicide attempters should get more attention in research to understand the biopsychosocial mechanisms playing a role in suicide attempts of young people. As suicide attempts most frequently occur in young people, further research is of considerable clinical importance.

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