1) below is a link to the study being referenced - it is real: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2869.1992.tb00019.x/abstract http://onlinelibr

1) below is a link to the study being referenced - it is real: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2869.1992.tb00019.x/abstract http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2869.1992.... 2) The study looked at 10 hrs daylight vs 16 hours of daylight. I wonder if "bi-phasic" sleep isn't just a quirk since the current consensus is humans need 7-9 hours of sleep a day. So, when you have less daylight - instead of sleeping continuously for 14 hours of night, you wake up at some point in between. The body simply does not need 14 hours of sleep per day. If this were true - and referencing the paul graham-ism about meetings breaking up the day into segments too small to be useful - it is possible that artificial light allows us to compress the night hours such that they fit our maximum need for sleep, and also give us larger continuous blocks of time to use during the day. from this perspective, artificial light supports human evolution by making us more efficient (rather than representing some undiscovered health problem). 3) Also interesting to consider how the northern-most europeans would have adapted, given extended daylight for months at a time. 4) lastly - it's awesome to see we are getting health advice from medieval times. During the same period, people commonly drank alcohol almost 100% of their waking hours. Alcohol certainly affects my quality of sleep and duration. On a related note - a study of the effect of continuous alcohol consumption on judgment might explain a lot of the wacky behavior back then.