Influence of seasonally adjusted exposure to cold and darkness on cognitive performance in circumpolar residents

The effects of seasonally adjusted 24-h exposure to cold and darkness on cognitive performance in urban circumpolar residents was assessed in 15 male subjects who spent three 24-h periods in a climatic chamber at 65° latitude during the winter (January–March) and/or summer (August–September). Each subject was exposed to three different environmental conditions in random order: (1) 22 °C temperature and 500 lx lighting; (2) 10 °C temperature and 500 lx lighting; and (3) 10 °C temperature and 0.5–l lx lighting. Accuracy on an addition-subtraction task was significantly greater in the summer than in the winter ( p = 0.038), while accuracy on a repeated acquisition task was significantly greater in the winter than in the summer ( p < 0.001). Independent of season, exposure to cold and darkness was significantly associated with a decline in response time on five cognitive tests, an improvement in accuracy on three tests measuring complex cognitive tasks, and a decline in accuracy on two tests measuring simple tasks. Increased performance on complex tasks may result from increased arousal in response to the combination of cold temperatures and dim light characteristic of the winter in urban circumpolar settings.