Mammalian activity – rest rhythms in Arctic continuous daylight

@article{Folk2006MammalianA,
  title={Mammalian activity – rest rhythms in Arctic continuous daylight},
  author={G. Edgar Jr. Folk and Diana L. Thrift and M. Bridget Zimmerman and Paul C. Reimann},
  journal={Biological Rhythm Research},
  year={2006},
  volume={37},
  pages={455 - 469}
}
Abstract Activity – rest (circadian) rhythms were studied in two species of Arctic mammals living in Arctic continuous daylight with all human-induced regular environmental cues (zeitgebers) removed. The two Arctic species (porcupine and ground squirrel) lived outdoors in large enclosures while the Arctic summer sun circled overhead for 82 days. Would local animals maintained under natural continuous daylight demonstrate the Aschoff effect described in previously published laboratory… 
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