I suffer from depression and PTSD. I started drinking diet soda to help me lose some weight. After about 3 months, I started to be plagued with constant anxiety, insomnia and irrational thoughts. I had read somewhere that artificial sweeteners can sometime negatively affect folks with mood disorders so I stopped drinking diet soda and guess what—I am feeling better, sleeping through the night and the irrational thoughts have subsided.
Seems to me the artificial sweeteners were having a negative effect on my mental health. I know I am going to avoid them in the future and drink water instead.