BBC - Future - How long can we stay awake? Link

http://www.bbc.com/future/story/20150220-how-long-can-we-stay-awake?lang=en&utm_campaign=10today&flab_cell_id=2&flab_experiment_id=19&uid=153834883&ocid=global_future_rss&utm_source=email&part=s1&utm_medium=10today.0224&utm_content=article&position=7&china_variant=False


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