Other fabrics like bamboo, Tencel, or other semi-synthetics are temperature-regulating, meaning they maintain a naturally cooler temperature and adjust with your body temperature. These are fantastic for keeping cool when it’s hot — especially because they are often moisture-wicking, too.

Prized for its warmth, flannel is primarily popular as a winter material. You can assess how thick and heavy a flannel sheet is by the GSM, or grams per square meter. A GSM of 130 to 135 is considered lightweight, 140 to 150 is considered midweight, and 160 or more is considered heavyweight.