In one study of reindeer, animals at 70 degrees North showed circadian rhythms in the autumn, winter and spring, but not in the suat 78 degrees North showed such rhythms only in autumn and spring.
In one study of reindeer, animals at 70 degrees North showed circadian rhythms in the autumn, winter and spring, but not in the summer. Reindeer on Svalbard at 78 degrees North showed such rhythms only in autumn and spring.