system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do anti-depressants have such a terrible effect if you miss one?

When I miss a day, I feel worse than I've ever felt before, why is this?
gpt
Antidepressants cause certain chemicals in your brain (usually serotonin, sometimes also norepinephrine or others) to stick around longer than normal.  After a while, your body gets used to this effect, and it starts producing less of them naturally.  But when you miss a dose of your drug, then suddenly they're not sticking around for that extended period, and your body isn't producing enough of them to make up the difference.  So you get a sudden drop in the levels of these chemicals, which plays havoc with your brain function.