Can you use FIR amethyst mats at night on a bed and how comfortable are they?

You can use one at night for up to 12 hours. We suggest you use a slightly warm comfortable temperature on the lowest levels (levels 1-2 of 7 or up to 50°C/130°F) and never use a temperature that is too hot. It is as comfortable as stone pads could be. It’s not the same as a spring mattress or a foam mattress. It has a flexible surface but it is made of hard stones. Most people enjoy lying down on this pad but don’t expect a soft mattress comfort. It’s different.