Riley has pretty much always been a vomiter. He just has bilious vomiting syndrom. It is mostly late at night or early morning. An empty stomach tends to bring it on. He gets a biscuit at bed every night and this has seemed to help alot. At 3-4 in the morning, when i hear that hacking sound i jump out of bed to get him out (or at least make it off the carpet)! Nothing wakes me up from a dead sleep faster then that! Just one of our many health issues.