Are you noticing how everyone loves 26yo Luigi Mangione, the UnitedHealthcare CEO killer? Zoomers will bring change. Millennials will forever be remembered as the biggest pussies the world has ever produced.
I'm not an expert. I wonder if it also relates to quality of sleep, cooler temperatures provide for better rest. A counter point might highlight that a lack of sunlight based vitamin D increases depression such as occurs in areas of seasonal sunlight deficiency and the S.A.D. phenomenon. Also worth asking if there was a control in place for temperature v sunlight exposure.