No — wearing a hat does not cause hair loss. This is a common myth. Hats don't cut off blood supply to the scalp or suffocate hair follicles under normal conditions.
The confusion usually comes from timing: many people notice more shedding around the time they've been wearing a hat often (e.g., during a stressful period, illness, or seasonal shedding), and mistakenly link the two.
The only realistic way a hat could contribute to hair issues is through traction — if it's worn extremely tight, for very long hours, every single day, over years — similar to traction alopecia from tight hairstyles. For the vast majority of people wearing hats casually, this isn't a concern.
If you're noticing unusual shedding, the cause is far more likely to be genetics, hormones, stress, or a nutrient deficiency — not your hat.