Department of Psychiatry and Psychotherapy, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.
Compr Psychiatry. 2012 Jul;53(5):535-9. doi: 10.1016/j.comppsych.2011.06.003. Epub 2011 Aug 6.
Seasonal spring peaks of suicide are well described in epidemiological studies, but their origin is poorly understood. More recent evidence suggests that this peak may be associated with the increase in the duration of sunshine in spring. We investigated the effect of number of sunshine hours per month on suicide rates in Austria between 1996 and 2006.
Suicide data, differentiated by month of suicide, sex, and method of suicide (violent vs nonviolent methods), were provided by Statistics Austria. Data on the average number of sunshine hours per month were calculated from 39 representative meteorological stations (provided by the Austrian Central Institute for Meteorology and Geodynamics). For statistical analysis, analysis of variance tests, Kruskal-Wallis tests, and Pearson correlation tests were used.
A total of 16,673 suicides with a median of 126 ± 19.8 suicides per month occurred in the examined period. A clear seasonal pattern was observed, with suicide frequencies being highest between March and May and lowest between November and January (df = 11, F = 5.2, P < .0001) for men (df = 11, F = 4.9, P < .0001) and women (df = 11, F = 2.4, P = .008). The average number of sunshine hours per month was significantly correlated with the number of suicides among both sexes (r = .43, P < .0001), violent methods (r = .48, P < .0001) but not with nonviolent methods (r = .03, P = .707).
This study shows that seasonal changes in sunshine account for variations in the number of suicides and especially violent suicides. We propose that sunshine, via interactions with serotonin neurotransmission, may trigger increased impulsivity and promote suicidal acts. However, because of the hypothesis-generating design of this study, more research is needed to further clarify the role of sunshine in triggering neurobiologic changes, which might contribute to suicidal behavior.
季节性春季自杀高峰在流行病学研究中已有很好的描述，但它们的起源尚不清楚。最近的证据表明，这种高峰可能与春季阳光持续时间的增加有关。我们调查了奥地利 1996 年至 2006 年间每月阳光照射小时数对自杀率的影响。
自杀数据按自杀月份、性别和自杀方法（暴力方法与非暴力方法）进行区分，由奥地利统计局提供。每月平均阳光照射小时数的数据由 39 个代表性气象站计算得出（由奥地利中央气象与地球动力学研究所提供）。为了进行统计分析，使用了方差分析检验、克鲁斯卡尔-沃利斯检验和皮尔逊相关检验。
在研究期间共发生了 16673 例自杀事件，中位数为每月 126±19.8 例。观察到明显的季节性模式，男性自杀频率在 3 月至 5 月最高，11 月至 1 月最低（df=11，F=5.2，P<.0001），女性自杀频率在 3 月至 5 月最高，11 月至 1 月最低（df=11，F=4.9，P<.0001）。每月阳光照射小时数与两性自杀人数（r=0.43，P<.0001）、暴力方法（r=0.48，P<.0001）显著相关，但与非暴力方法无关（r=0.03，P=0.707）。
本研究表明，阳光季节变化解释了自杀人数的变化，特别是暴力自杀人数的变化。我们提出，阳光可能通过与 5-羟色胺神经递质的相互作用，引发冲动性增加，并促进自杀行为。然而，由于本研究的假设生成设计，需要进一步的研究来阐明阳光在引发神经生物学变化中的作用，这些变化可能导致自杀行为。
