Using previous research that shows that insomnia causes a decrease in blood flow in the front dorsal lobe of the brain, and correlates it with depression, the authors of a Japanese study seek to establish a link between insomnia and depression. The study “Insomnia and depression: Japanese hospital workers questionnaire survey” is published in De Gruyter’s open access journal Open Medicine.

Suicide is one of the leading causes of death in Japan. The yearly financial cost to the Japanese economy of depression and suicide is estimated by UPI to be US$4.1 billion. Middle-aged males, one of the groups that was found to suffer the highest rates of insomnia are also the likeliest to commit suicide.

In March of 2011, over 7000 hospital staff in ten hospitals in the district of Rosai were given a self-administered anonymous questionnaire. The questions included information about the respondent’s gender, age, and medical profession, as well as questions about their sleeping history two weeks prior to responding to the survey, as well as detailing their overtime work, and their history of disease, and chronic pain. It also asked them to assess their own feelings of depression and fatigue.

The results found that 13% of men, and 19% of women suffered from insomnia, and the medical profession with the highest rate of insomnia were nurses at 20%. For comparison, about 10% of Americans suffer from chronic insomnia.

Chronic insomnia can lead to depression, and a better understanding of the link between the two conditions could be used to improve treatment, and prevent the condition from worsening while strengthening the world economy. The hope is a survey will be developed for healthcare professionals (and other high-stress professions) that can identify insomnia before it becomes a problem.