The Dangers of an Extended Meditation Session The Buddha was said to have meditated 40 days and 40 nights in a single sitting which begs the question is it possible to sit this long without any physical or mental injury?

As an example, my meditation sessions vary in discomfort. Sometimes when it's good, I wish the alarm hadn't rung  and then sometimes my foot falls asleep in 5 minutes.

There's this theory I have that when meditation is done properly (i. e. you are not fighting yourself), the body will begin to self-regulate itself and the mind will begin to heal. 

Elsewhere, I have read that its good not to sit more than 40 minutes. Is this more of a legal disclaimer to prevent novice meditators from injuring themselves? 

What I really want to know is that if you're comfortable and physically able to sit 40 days and 40 nights, is it OK to sit that long? I guess there's a chance you may be stuck in that meditative state. Have there been reports of meditators who don't return to their consciousness? Are there any reports of people who have tried it?
According to Empty Cloud The Autobiography of Master Xu Yun (famed Chinese monk of the 20th century usually with name transcribed as Hsu Yun).


  One day I cooked taro in a cauldron and sat cross-legged while waiting
  for my meal to cook and involuntarily entered the state of samadhi.
  
  MY 63RD YEAR (1902/03)
  
  Master Fu-cheng and others who stayed in nearby huts were surprised
  that I had not called on them for a long time and came to my hut to
  present their New Year greetings. Outside my hut, they saw tigers’
  tracks everywhere with no traces of man. They entered my hut and
  seeing that I was in samadhi, they awoke me with a qing (a musical
  instrument made of stone, the sound of which is subtle but
  penetrating). When I returned to self-consciousness, they asked me,
  ‘Have you taken your meal?’ I replied, ‘Not yet, the taro in the
  cauldron should be well cooked by now.’ When its cover was lifted, the
  cauldron was covered with an inch of mould. Fu-cheng was startled and
  said, ‘You must have been in samadhi for half a month.’ We then melted
  ice, cooked taro and ate our fill. They joked with me and left.


Now you can take this story with a grain of salt, but I wouldn't discount the possibility of hibernation-like state for deep meditation...