单项选择题

E
Have you winterized your horse yet Even though global warming may have made our climate more mild, many animals are still hibernating(冬眠). It’s too bad that humans can’t hibernate. In fact, as a species, we almost did.
Apparently, at times in the past, peasants in France liked a semi-state of human hibernation. So writes Graham Robb, a British scholar who has studied the sleeping habits of the French peasants. As soon as the weather turned cold people all over France shut themselves away and practiced the forgotten art of doing nothing at all for months on end.
In line with this, Jeff Warren, a producer at CBC Radio’s The Current, tells us that the way we sleep has changed fundamentally since the invention of artificial (人造的) lighting and the electric bulb.
When historians began studying texts of the Middle Ages, they noticed something referred to as "first sleep", which was not clarified, though. Now scientists are telling us our ancestors most likely slept in separate periods. The business of eight hours’ uninterrupted sleep is a modem invention.
In the past, without the artificial light of the city to bathe in, humans went to sleep when it became dark and then woke themselves around midnight. The late night period was known as "The Watch". It was when people actually kept watch against wild animals, although many of them simply moved around or visited family and neighbours.
According to some sleep researchers, a short period of insomnia (失眠) at midnight is not a disorder. It is normal. Humans can experience another state of consciousness around their sleeping, which occurs in the brief period before we fall asleep or wake ourselves in the morning. This period can be an extraordinarily creative time for some people. The impressive inventor, Thomas Edison, used this state to hit upon many of his new ideas.
Playing with your sleep rhythms can be adventurous, as anxiety may set in. Medical science doesn’t help much in this case. It offers us medicines for a full night’s continuous sleep, which sounds natural; however, according to Warren’s theory, it is really the opposite of what we need. The example of the French peasants shows the fact that ______.