I have attended a LOT of trade shows and I have been watching people purchase thousands of the inexpensive sheet sets that were originally touted as Egyptian cotton. Most places you go now will no longer have the word ‘cotton’ in their promotion or on their banners. This is because the products were never cotton and regulatory boards in different areas forced most people to be a little more honest. Any of these sheets that I have found are 100% synthetic.
I cringe every time I see someone carrying these cheap sheets around at trade shows!
The best thing for sleeping is to use cotton sheets. There is a great article/video here by Dr Mercola that tells you why this is so. Dr Mercola about bedding.
Synthetic sheets are less expensive but you will pay for it in less restful sleep. He likes wool as a filling – personally, I prefer silk. Silk is lighter and I find cooler in the summer and warmer in the winter and is lighter. And dust mites and other insects will not pass through it.