Seasonality and time-related aspects of suicides in Greece: an applied time-series analysis

Abstract

The background that underlies each committed suicide varies among people and constitutes a complex structure of psychological, behavioural and biological risk factors that may be triggered by external conditions. Recent studies have shed new light on the association of suicides with particular days and periods of year, in an attempt to resolve the inconsistencies met in literature regarding this relationship. The aim of this study is to look into any time-related patterns on suicides in Greece and to do so we analyzed the frequency of suicides over a period of 13 years (2000-2012) in terms of day of the week, month, major celebration and season. A seasonal ARIMA model revealed the association between suicide frequency and month of year, with a peak to be reached in May and July and increased numbers of suicides to be reported during spring and summer months. Monday was the most frequent day of suicide occurrence whereas Sunday was the least one. A season pattern of suicides was validated. The increase of suicide occurrences on Mondays could be explained by the “broken-promise effect” which has been described as the consequence of frustrated expectations of the weekend. Suicide peaks in spring and summer may be explained partially by biological factors (e.g. serotonergic alterations) as well as the experience of depressed people perceiving the social and emotional contrast to other people that enjoy outdoor activities at that period.