Both my son and my daughter had this issue. Unfortunately, we didn't realize it until my daughter came along that, even though they both put their fingers in their mouths, the throwing up wasn't intentional. Talk about mommy guilt with the older one! Rather it was a food sensitivity that caused an upset tummy. With my daughter it was mac and cheese that did it every time, as soon as she lay down. It was worse if either one was overstimulated before bed.Since your son is just 16 months and has probably been introduced to a few new foods recently, my suggestion would be to make sure this isn't the problem, first. If that's not the issue, then remember that at 16 months his long term memory is not developed well, so any discipline would need to be very consistent and repetitive. Personally, I like the quiet clean up, quick hug, and right back to bed approach. This way he knows that it's still bed time. A time out would just keep him up longer...and really isn't all that effective at this age. Just my two cents.