Fibres often favoured for breathability in bed linens include Pima cotton, linen, and silk. Real silk sheets are as expensive as they are luxurious and must be dry-cleaned. Cotton-polyester blends are popular for their no-wrinkle ease, but are less breathable than all-cotton sheets, which can make them less comfortable in warm weather. The most comfortable cotton-polyester blends will be those that are at least 50 percent cotton. Polyester is also blended with cotton to make microfibre, which wicks moisture, making it a comfortable fabric for people who tend to become warm at night. 

When Top sheets come with thread counts that range from 100 to 1,500 threads per inch, it can be difficult to decide which ones are good, or even good enough.

We will simply say that sheets from 200 to 400 threads per inch are very comfortable and durable. Sheets up to 500 threads per inch are likewise comfortable and durable. Beyond 500 threads per inch: sheets are likewise comfortable and durable. The difference, in most cases, is related to how threads are counted under international regulations, not the actual number of threads in the sheet.

So while a sheet with fewer than 150 threads per inch will certainly feel rough to many people, most people will not experience a difference in comfort or durability over 500 threads per inch.