The military has wrapped up the first phase of a sleep study at Canadian Forces Station Alert in Nunavut's High Arctic.

Researchers chose CFS Alert because of its extremes of no sunlight in the winter and 24 hours of light in the summer.

A scientist with Defence Research and Development Canada, Michel Paul, wants to find out why people have trouble keeping their spirits up in the dead of winter.

“Seasonal Affective Disorder is effectively a winter depression," he says. "If that occurs down at the U.S. border, what's it going to be like in the Arctic?”

He helped run the study at the Alert station. Thirteen military volunteers spent January and February jotting down their sleep patterns in a logbook. They also wore bulky wrist monitors to keep tabs on their sleep.

For part of the study the volunteers sat through two 24-hour tests spending an entire day in almost total darkness at the base's gym. Researchers kept a close watch on the volunteers' melatonin levels. That's the sleep-regulating chemical affected by the body's exposure to light.

Paul says one of the study's main goals is to help people be more functional in extreme climates.

“Not necessarily everyone comes down with depression, but they certainly have extremes in their circadian physiology and we're trying to correct those things,”  he says.

Phase two of the study is slated for June when researchers will be studying the effects of 24-hour sunlight.