"Our genes havent really changed in the past century. Genetic predisposition cant explain why so many of us have started to have more trouble falling asleep. The vast majority of the story has to do with our environment. Good sleep hygiene, many researchers have found, is essential when it comes to falling asleep; it can even overcome some unfortunate genetic predispositions. Conversely, bad sleep hygiene can equal, in its effects, some of the most problematic genetic disorders."Source: Why Cant We Fall Asleep? - The New Yorker
