The study, reported in Circulation: Journal of the American heart Association, looked at heart risks related to three major insomnia symptoms compared to people who rarely or never had these problems.

Although the research station is far from major sources of human pollution, atmospheric circulation brings air from Europe and North America into the Arctic region.

Its metaphor makes West Superior ‘the center of cardiac or heart circulation’; the railways become major arteries; and New York is ‘the umbilicus through which this man of commerce was developed’.