I remember reading some stats. outta` the States a few years ago. About half of motorcycle crashes with no other vehicle in the mix, were alcohol involved. Now add weed into the numbers, with many people thinking it has little effect on driving/riding, numbers are likely overall more substantial.
I don’t doubt it contributes. I tend to keep riding and anything mind altering strictly separated, not only because it seems foolish to mix the two to begin with, but also because obviously given the nature of my job my entire career hinges on my clean and valid license.
There are plenty of days when I am sitting out by the pool in the AM deciding if I want a drink or a drag of something, but then also thinking I may want to go out for a little ride somewhere later in the day, so I end up torn, but I always strictly opt for one path and never both
Dehydration and heat fatigue can be factors.
Honestly this is one of the biggest reasons that I will readily admit to not being an ATGATT guy - I naturally run hot to begin with (I’m that guy you see in January and February running around in shorts shovelling their driveway lol) and if I get to a certain point I do legitimately have concerns for ending up in a heat stroke or loss of concentration/pass out type scenario where the results could be catastrophic. So I ride with less gear to stay cooler and make one safety trade-off for another safety trade-off in the end.