Along with your concrete bed, you get a wooden pillow, which apparently was used in the Buddha's days and is still used in some rural areas of Thailand.

This is a wooden block with one concave side where you rest your head.

It's about as comfortable as it sounds, but it is possible to have a good night's sleep with it.

Taan Mehdi is a big fan of the wooden pillow and mentions it a lot in his talks, with much intended humour.