Babies and adults respond differently to colour. The most calming colour for a newborn is red, presumably because up until birth it was the only colour they ever saw (when light came though the belly - think closing your eyes and turning our face to the sun). If i were you i'd get one of those over-the-cot rails to hang an organza curtain from (think princess style bed, you know what i mean?) and buy a bunch of red linen or organza to hang from it so you can enclose the cot in it when it's sleepy/nap time. Or you could make a red linen ring sling like mine If you DID use a rail for a curtain you could also experiment with different colours to see what bubs likes best.

Bx