Target’s Casaluna 300 Thread Count Temperature Regulating Sheets are a cotton and polyester blend incorporating 37.5 Technology, which, according to the company that makes it, is a mix of volcanic minerals and activated carbon that comes from coconuts. Wes Burgess, chief product officer at 37.5, told me the technology is designed to absorb water vapor around your body to help keep you cool. In a patented process, the volcano minerals and activated carbon are blended with either nylon or polyester to create a wicking yarn that can then be woven with other yarns (like the cotton and polyester in these Target sheets). The 37.5 particles are permanently embedded, so they shouldn’t wash out over time. Several companies use 37.5 in a range of products, including athleticwear. I can’t say how effective it is in other products, but it didn’t add anything to these Target sheets—they didn’t make us sweat overnight, but they were hot, scratchy, and unpleasant to sleep on. They also had loose threads around the edges, and they didn’t live up to the construction quality of the other sets I tried or to the quality of other Target sheets we’ve recommended for years.
