When my son and daughter-in-law were pregnant they took a class through the hospital about how to care for their baby.  They were told to put their baby to bed and let it cry itself to sleep.  Big mistake!!  Nolan didn't cry himself to sleep.  He screamed.  It was not unusual for him to scream for 30 minutes or longer.  This did not improve.  As he got older he was determined no to go to sleep and would just keep screaming.  At one point my son took Nolan up to the neighbor in the condo above them to apologise for his screaming.  Everyone was at their wits end (including grandma).  That was when I researched the different ways that animals sleep.  At first he didn't understand the book was written about him, but as he got older he understood.  He no longer screams himself to sleep!