You might be surprised to learn how much sleep a newborn needs. While they may not sleep in large chunks at a time, they do need 16 to 17 hours a day. But, your newborn also cycles through sleep very quickly, going from deep to light sleep every couple of hours. Nightwaking is a survival trait that helps babies communicate what they need. For more specifics on newborn sleep habits, visit the American Academy of Pediatrics' website.
Over the years, there have been a lot of developments and research done on sleep training and crying it out. A newborn cries for a reason, and that is to communicate a need. It is your job as their parent to decipher that need. If you are waiting until your baby is crying to determine what their needs are, you may be waiting too long. This also means you should never let a baby "cry it out." Contrary to what sleep training advocates would like you to believe, this is actually a cruel and psychologically damaging thing to do to a baby. Read more about the long-term effects here.