Settling hysterical overtired baby

[pleasethanks]

Okay, so you are trying to settle your baby for a nap, they take ages to settle and then descend into the overtired cry, frantic and rather hysterical...how do you deal with it? Do you try and calm them and continue getting them to nap or just give up? I need help!

with dd2, i give it 20 mins tops - just sitting still in a very quiet room. if the crying isn't reducing in pitch and tone, then we go for a wander round the house for 5mins, come back and try again. i think dd2 can sometimes work herself into a state and then she doesn't know how to stop crying, IYSWIM, so i have to do something completely different to distract her if this is the case.

I've read on here sticking them in front of a plain light wall can calm them down.