Because gentle jiggling/rocking tends to calm babies. Mine, anyway. Sometimes, gentle jiggling doesn't work, so you do it a bit more. Nothing much, just kind

Because gentle jiggling/rocking tends to calm babies. Mine, anyway. Sometimes, gentle jiggling doesn't work, so you do it a bit more. Nothing much, just kinda a joggle with the knees, but the increased frequency/amplitude works better sometimes. Add the factors explained above, and sometimes you end up shaking that kid for all he's worth. I managed to avoid doing so, though. :)