Training for food and sleep deprivation

[gmanflyarmy]

One day I was working out and it hit me....a person could be a complete physical freak and still fail at various points in the SF selection. Correct? They could read all they want for preparation, but still fall victim to surprises or things just hard to train for. The two I thought of is sleep and food. Now, I have not attended SFAS or any other part of the pipeline, so I'm only figuring that instructors will try to make candidates uncomfortable as possible...within reason, to represent situations they could in encounter later-on. Is this correct?

So that said, is there any smart way to condition one's body for to these mental tests? That is training for sleep deprivation and/or minimal food?