Head Banger! (or if it's not one thing it's another!)

[Fuzzled]

Hi!
Hoping someone has some sage advice the guts to tell me I'm being an arse!
We've managed to get 9mo DS to sleep through barring odd nights with teeth (just for the record, I can't recommend the "No Cry Sleep Solution" enough!) but he's a very wriggly sleeper and his new trick is to wiggle his way up the bed and smack his head off the top of the cot bed. As it has a solid head/foot end, it therefore makes a lovely thwack noise and sounds like a gunshot on the monitor!
When attending classes before the birth, the HV giving the classes advised never to use cot bumpers as the baby could suffocate. I can see the point with a new born, but would the same apply to a 9mo who is almost walking?
Alternatively, does anyone have any other options?

[Fuzzled]

Shameless bump!