The most popular thread type for bed sheets is 100% cotton. Cotton is a soft, breathable, and durable material that is widely used for bedding. Within the category of cotton bed sheets, there are different types of weaves and finishes that can affect the quality and feel of the sheets. (Keep in mind 100% cotton is considerably rougher until you have washed it many times)
Some common cotton weaves for bed sheets include percale, sateen, and jersey. Percale is a crisp and lightweight weave, while sateen has a smoother and more lustrous finish. Jersey is a knit weave that is stretchy and more casual in appearance. The choice of weave can affect the texture, breathability, and durability of the sheets.
In addition to cotton, there are also other popular thread types for bed sheets, such as linen, bamboo, and microfiber. These materials have different properties and benefits, and their popularity can vary depending on personal preferences and market trends.
(My peronal favourite is a 50/50 blend of Bamboo and Cotton it is both smoother to the touch right away and cool to the touch as well)