ALT Graphical abstract describing the research: Curls keep you cool! Tightly curled hair offers greater protection from solar radiation heat We came to this conclusion by running a series of experiments We used lamps to simulate solar radiation  We used a thermal manikin to measure heat transfer We put wigs with different textures on the manikin  We ran the experiments with different wind speeds and with dry and wet scalps (to simulate sweat) For each combination of factors we measured heat transfer from the scalp Our results likely reflect the fact that tightly curled hair creates more distance between the scalp and the top of the hair