The number of suicides by middle-aged men in Japan tends to surge on Monday mornings, according to research conducted by a team from Waseda University and Osaka University.

The psychological state of so-called blue Monday, in which people become depressed as Monday approaches, has been well known.

But this was the first research to find, based on data analysis, the specific times of the day with a number of suicides, according to the team. The research group is hoping the result will be utilized to devise effective suicide prevention measures, such as expanding telephone consultation services during the times of the day when many suicides tend to occur.

Through an analysis of data on some 870,000 adults who took their own lives in Japan between 1974 and 2014, the team found that days of the week and times of the day when people tend to die by suicide differ by sex and age.

Among men aged 40 to 65, suicides between 4 a.m. and 7:59 a.m. hit a peak during the period from 1995, when Japan’s economic conditions began to deteriorate, to 2014. Men in that age group had a higher rate of suicide than men and women in other age groups.

The number of suicides among men in that age group during the daytime was 1.57-times higher than late at night. The number of middle-aged men who took their lives on Mondays was 1.55 times as high as that on Saturdays. The same pattern was also seen for men aged 20 to 39, but such a trend was not seen before 1995, according to the group.

It is believed that many men took their lives before leaving home for work in the morning — as opposed to during their commute — as most cited causes of death were hanging and gas poisoning, the group said.

Men age 66 and older and women in general tended to take their own lives during the daytime, hitting a peak at around noon, the group said.

While telephone consultation services to prevent suicides are often offered from evening to late at night, the researchers say such services should also be offered during early morning hours. The group also called for more community support for women and the elderly, who are thought to be taking their own lives during the day when they are alone at home.