How can I stop to exit main function? and Is infinite sleep consume many CPU usage?

Q1.Is it a good way adding "while&sleep" in order to avoid to exit main function like below?

main()
{
  run thread

  while(1)
    sleep(0xFFFFFFFF);
}

Q2. Are the two differ in terms of CPU perspective?

Case1)

while
  sleep(1);

Case2)

while
  sleep(0xFFFFFFFF);