This from the Canadian Broadcasting Corporation, from an Arctic-wide PR tour by Canada's Defence Minister:
Michel Paul, a specialist in fatigue countermeasures, and social psychologist Don McCreary are researchers with Defense Research Development Canada. They are launching a three-year study of daylight and darkness exposure on military personnel.

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Both scientists expect to gain physiological and psychological insight from the Canadian Rangers, who act as the country's military presence in the north and who have lived in the region their whole lives.

Paul says he and McCreary hope their discoveries will make it easier for troops to sleep in the summer and avoid the seasonal depression that can occur in Arctic darkness.

"The military is very interested in improving, if not just sustaining, operational readiness at any time," said Paul.

He will be studying melatonin, a compound our bodies create when we are exposed to darkness. It can make a person feel tired over the course of a long Arctic winter and prolonged exposure to the compound can lead to depression.

"Melatonin is sometimes referred to as the hormone of darkness, or a biochemical manifestation of darkness," says Paul.

As it is now spring in the Arctic and daylight hours are increasing, he'll study the effects of summer sun exposure on melatonin levels.

McCreary, meanwhile, hopes to build on research in Antarctica about depression and conflict among people who work in confined and extreme environments.