when dealing with older kids who should have more intact and mature sensory processing (around age 7), i would tell a parent that we all have an "best setting" for getting information from the world. too much stimuli makes us uncomfortable and we retreat... too little and we seek out more stimuli.
rocking gives our bodies input because the body uses the movement's inpact on our inner ears to do little background movement calculations to help our awareness of our position in space
that's the science bit which, like i said, doesn't apply brilliantly well. how old is your lo? maybe what you need is a mobile over the cot/ some white noise or music playing to send him off to sleep or maybe being in your arms was calming despite the exciting environment. Swaddling helped us get our ds to "switch off" and sleep until he was about 4 1/2 months
