I think it is the gut microbiome and chemicals. Basically drink too much alcohol, get depressed or inferred from the hangover. It's a negative feedback look b/

I think it is the gut microbiome and chemicals. Basically drink too much alcohol, get depressed or inferred from the hangover. It's a negative feedback look b/c usually drinking relieves depression at first. Then fail to eat properly for what you and your microbiome need, you get depressed. Tryptophan depletion for example. Take a serious course of antibiotics get depressed since your microbiome is out of whack. There's probably genetics involved as well. Sun light exposure modulates hormones and Vit D. I wonder if there's a correlation with caesarean section births and depression as well. The hypothesis would be that the infant is born into a sterile environment and does not get populated by the moms microbiome. Exercise probably plays a role as well since it boosts resilence.