Time patterns and seasonal mismatch in suicide


Dr T. Partonen, Department of Mental Health and Alcohol Research, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland
E-mail: timo.partonen@ktl.fi


Objective:  Physical time-givers may have a modifying effect on the time patterns of death from suicide.

Method:  Data on a total of 1397 suicides in Finland over a year were collected using the method of psychological autopsy. We linked versatile information on each individual to meteorological data adjusted for local weather conditions, and to the universal astronomic data.

Results:  The number of suicides with seasonal mismatch was greater than the expected in the northernmost region of the country (P = 0.03). The northern location was the most significant predictor of such suicides (P = 0.001). They were associated with the changes in ambient temperature during the preceding day (P < 0.00001), the changes to colder preceding suicides in the spring.

Conclusion:  Our findings show that mismatch between the changes in ambient temperature and those in the length of day may precede death from suicide in some individuals.