Fever blankets are a traditional thing that's existed throughout the generations as part of the routine your parents would put you through when you're sick. Linen naturally thermoregulates - it doesn't let you get too cold, and it doesn't let you get too warm. Part of this is to do with it's ability to wick away sweat when you're hot, but dry fast enough to be warm when you're cold.

Even under a duvet or other blanket, it can help keep you comfortable. So aside from being a great throw for the sofa, it has function other than the aesthetic.