should you use sheets in a travel cot?

[olivhohoho]

we have bought a samsonite pop up travel cot (the one for use up to 18 months, not the baby one) and are going away this week. dd sleeps in a grobag but should i have a sheet on the bottom over the matress? if so, do you get special ones or just use a normal cot one? she is often sick so usually put a muslin over the head area of her moses basket as well as bottom sheet.

TIA

We use a normal cot one in our travel cot - purely because I don't think you can get the cover off the mattress on ours to wash it. Just keeps things cleaner. And smelling of home, iykwim, which can be comforting.