But on the northern coast of Alaska, many communities this time of year have no darkness at all.

NPR: Life in the Land of the Midnight Sun

The best time of year to see them is during winter, when darkness in the upper latitudes stretches up to 24 hours.

CNN: 'Dancing lights' draw thousands to frozen north

The data that he and his team have collected suggest the animals plan their moves with guerrilla-like precision, sprinting from the safety of one game reserve to another under cover of darkness and spending as little time as possible in the poacher-infested areas in between.

ECONOMIST: Elephant behaviour

And his biggest fear, he said, was the prospect of having to swim with all of his equipment for up to two hours at a time in darkness.

BBC: Explorers begin epic Arctic trek

"It's not very good, especially this time of year when we're having to walk to work in the dark, complete darkness, " Ms Twogood said.

BBC: Dorset midnight street light switch-off to continue