Higher Risk of Suicide on Milestone Birthdays: Evidence from Japan

Recent studies suggest that the risk of suicide is higher during and around birthdays. The so-called "birthday blues" might be stronger on birthdays at milestone ages (e.g., 20, 30, 40), as these symbolic ages might represent occasions for existential stock-taking that may highlight failures and underachievement in life. Moreover, in some countries (including Japan), certain symbolic birthdays come with the expectation of celebration with family and friends, and thus such special birthdays may elevate the birthday blues if there is nobody to celebrate the occasion with. This study examines the possibility that there are more suicides on milestone birthdays than on other birthdays or days other than birthdays, using approximately one million individual death records between 1974 and 2014 in Japan. Graphical analysis and Poisson regression analysis showed that suicides occurred more frequently on milestone birthdays when people turn 20, 30, 40, and 60. This pattern was predominately observed in men. Our findings suggest that it is crucial for health professionals and family members to pay close attention to vulnerable individuals as their birthdays approach. In particular, individuals are at a higher risk when birthdays coincide with occasions of social significance, including the ages of adulthood (age 20) and retirement (age 60).