mermaid bridal gown with sleeve

I have been wedding dress shopping and I finally found the dress. It needed sleeves added....and that got me to thinking about sleeves in history!
In the Roman times sleeves weren't much of a thing, based on the pictures I've seen. That doesn't seem all that practical in the northern climates. Sometime around maybe the fifth century you start seeing sleeves....and they're long sleeves. You don't even see short sleeves until the mid-1600s....Sure you have the slashed sleeves and the long sleeve shifts worn under sleeveless overdresses, but there are still sleeves. mermaid bridal gown with sleeve
I find it fascinating that in a period roughly of a century you go from mostly sleeveless garments to full length sleeves and then after about a thousand years (if I've done my math right), you have short sleeves making a comeback.
So what do you all make of that (not that I expect anyone to really be that fascinated in this subject) rather sudden change in fashion? Was it the cooler climate or religion or both? In the summer I can't imagine wearing the layers of clothes that you see in medieval times... but then again, wool and linen-- the most common fabrics-- actually breathe quite well.