I have pretty bad depression and mindfulness (metacognition/awareness of your emotions) have a lot to do with memories. I'm often not "aware" that I'm happy/sad/angry, etc. and my memories reflect that. Just taking a moment and thinking about what I'm currently feeling can be surprising to me.

I think this relates a lot here, people who are well aware of their emotions may observe the effects the drugs have on them, not just when they're high/coming down but also it's affects on their day to day lives.