Those who wear wigs, hats, helmets, and headbands, etc over a long period of time should adjust the timing of usage appropriately and make sure to massage the scalp. When the scalp is trapped in an environment where is not well ventilated, heat and sweat are unable to escape, and the scalp will thus be susceptible to bacteria, resulting in hair loss. It is usually best not to wear a hat, on one hand to avoid spoiling the hair due to stuffy conditions, and on the other hand to prevent the scalp from being oppressed by the brim of the hat, causing hair loss.
To keep warm during winter, you can and should wear a hat when going out, but are advised to take it off when indoors. People with hair loss problems should not wear a hat over a long period of time, in order to avoid exceedingly tight fitting caps that will hinder blood circulation of the scalp and result in more severe hair loss.