Why wear a hat and sunglasses during Ironman

I’m just watching the live coverage from IM Copenhagen. I see a lot of athletes wearing a hat and sunglasses. The weather is 18C with intermittent rain. I don’t understand why folks would wear a hat or sunglasses?

Personally I get hot running in a hat and don’t understand the benefit?

Sunglasses gradually get blurred with sweat and grime and are just a PITA.

I have worn a hat and glasses in every IM race I’ve done, but I never train wearing them and I’m now wondering why I bother.

In all the marathons I’ve watched, I’ve never seen any Kenyans wearing a hat or sunglasses, and they sweat a ton. In fact the only elite runner I can ever remember wearing a hat on occasions is Deena Kastor.

So why do so many triathletes wear them?

To add to this, I don’t understand why track athletes where sunglasses in a track race other than them being prescription sunglasses. This is why I wear mine…it’s my prescription. A hat is only useful if there is a ton of sun and heat. If not, it is additional weight when it is wet. Every gram adds up. I don’t even like wearing clothing that gets heavy when wet. I literally compare the fabrics of the race outfits when wet go go with the minimalistic ones and try to keep all water off my feet. I used to train in XC skiing with a guy who ran 2:12 marathon and was on the 1980 Olympic marathon team (never got to go due to boycott). When you train with someone like that they are obsessive about minimizing carrying anything you don’t need to.