cotton polyester fitted sheets

Don't feel that you have to stick to the materials on this list. I just finished testing the Naturalmat Organic Hemp Bed Linen Collection, and I can't stop talking about this miracle material. Hemp combines all the best bits of linen, in terms of breathability and durability, and it's that little bit softer to suit sensitive sleepers. If you're looking for something more luxurious, the Shleep Luxury Merino Wool bedding set could be right up your street. 

...

First of all, because linen’s flax fibers are slightly longer than those of cotton and wrapped a little tighter, linen sheets are stronger which means they will last much longer. If softness is a factor for you, you may want to consider cotton, though. Flax fibers are much rougher than cotton resulting in slightly crisper fabric. But the great thing about linen is that it gets softer after each wash, so essentially it gets better with time.

...