Are men allowed to sleep on a real silk pillowcase?

So men are not allowed to wear silk in terms of clothing or even lie on silk, the hadith mentioned by Imam Abu Dawud. Now, what I would suggest is that look at the label and see whether it's pure silk. If it is pure silk from the silk worm, this is what the prohibition refers to. If it is synthetic silk, which is normally the case, then that is fine, but pure silk is very expensive nowadays, so just check the label and then you'll be able to know which one it is.