These are dangerous times: suicide rates go up in the Spring and during an economic downturn, an analysis of suicide trends published Friday shows.
Add a couple of other known risk factors for taking one's own life - being a man, a doctor and a smoker, for example - and one has a potentially lethal cocktail of conditions, the study suggests.
An estimated one million people commit suicide each year, accounting for 1.5 percent of all deaths worldwide, according to the survey, conducted by Keith Hawton of Oxford University and Kees van Heeringen of University Hospital in Gent, Belgium.
Incidence, however, varies greatly from one country to another, and even across different latitudes.
Finland, Latvia, Hungary, China, Japan and Kazakhstan all have exceptionally high rates of suicide, 20 per 100,000 people or higher. In Lithuania the rate is almost 40.
In general, suicide is a major concern in the former Soviet states, notes the study, published in the British medical journal The Lancet.
In China, suicide accounts for 3.6 percent of all deaths, and 30 percent of suicides worldwide, far above its proportion of the global population.
Just below the world average of 15 suicides per 100,000 people are the United States, Canada and Australia, with rates dropping below five per 100,000 in Greece, Mexico, Brazil, Iran and Egypt.
Within Europe, living in sun-deprived northern countries seems to boost the risk of taking ones own life, especially in the Spring, though scientists are not sure why.
One theory suggests the reasons are biological, with the change of season after a period of prolonged darkness provoking some as yet unknown neurochemical imbalance.
Another theory is social: seeing other people who appear happy may be especially hard to take at that time of year.
In rich nations, for every woman who takes her own life, two to four men will do the same. In developing countries, the ratio is more equal, though it may be moving in the same direction.
China is the exception, with significantly more women dying by their own hand.
Suicide, not surprisingly, is more common among the unemployed, though there may also be a secondary link with mental illness, which can often be a barrier to finding and keeping work.
"Previous recessions have been associated with increases in suicide, especially in younger men," Hawton told journalists by email.
There are also ethnic disparities. Europeans and Americans have higher suicide rates than Hispanic or African Americans, though in the United States the gap is narrowing due to a surge in death rates among young black men.
Some of the highest rates are to be found among aboriginals in the United States and Australia, perhaps due to cultural and social marginalisation as well as alcohol abuse, the authors say.
Work profiles matter too. "Risk tends to be elevated in people in occupational groups with easy access to means for suicide - doctors, farmers, pharmacists, dentists, veterinary surgeons and police in countries where they regularly carry guns," Hawton said.
Among medical professionals, female doctors are most at risk.
Differences between the sexes show up in methods chosen. Men prefer fire arms and hanging, while women opt for less violent means, especially poisoning. In South Asia women commonly set fire to themselves.
Mental health plays a major role in suicide, the study shows. Some 90 percent of people who take their own lives are thought to have some form of psychiatric disorder.
Depression ups the risk by 15 to 20 times - fully four percent of patients diagnosed as depressive die by their own hand.
Other factors that increase the odds of ending it all are persistent sexual abuse in childhood, population-wide events such as natural disasters, and the death of celebrities.
Suicide rates rose by 17 percent following the death of Diana, Princess of Wales in 1997 in a car accident in Paris.
War and major terrorist attacks, however, decreases suicide rates, probably due to the social cohesion it creates in communities.