Christopher Coates 
The Ark [EPUB ebook] 

The Earth as we know it is about to end.
Technology has developed to the point where a person can be placed in a Sleep State: a cross between suspended animation and a drug-induced coma.
Just as the trial of the new technology is being completed, an unusual comet is discovered approaching Earth, bringing with it radiation that will wipe out all life on the planet. Soon after, the government builds a sleeper facility to save humankind from extinction, taking drastic steps to maintain secrecy of the project.
But when the sleepers awaken, they discover that something has gone terribly wrong… and that the strange world around them is not the one they fell asleep in.