"I call the bottom bunk at Gitmo," Snowden joked, referring to the US detention center at Guantanamo Bay, Cuba, says the book to be released Tuesday, excerpts of which were published Monday in The Guardian.
Greenwald, recounting the series of discussions last year in Hong Kong when the former National Security Agency contractor decided to reveal his identity, said Snowden appeared to sleep soundly and was "completely refreshed the next day" despite the tension.
"When we asked him about his ability to sleep so well under the circumstances, Snowden said that he felt profoundly at peace with what he had done and so the nights were easy," said Greenwald, who met with Snowden in Hong Kong with Laura Poitras and Ewen MacAskill.
"'I figure I have very few days left with a comfortable pillow,'" he joked, 'so I might as well enjoy them.'"
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He wrote that two human rights lawyers arrived at the hotel where Snowden and three journalists were staying to assist Snowden, but that Greenwald had to find a way to get him away without confronting the horde of media.
Snowden said he had a way to make himself "unrecognizable" but they needed a way to get him away without being followed, Greenwald wrote.
"We came up with a plan: I would walk out of the hotel room with (Guardian lawyer Gill) Phillips and go down to the lobby to lure the reporters, still waiting outside our door, to follow me," the journalist wrote.