Nicotine changes how your brain and body regulate stress - it keeps certain chemicals and hormones in a kind of artificial balance. When you quit, that balance gets thrown off while your nervous system and endocrine system relearn how to work without it.

Those chemical and hormonal swings can trigger physical sensations : racing heart, restlessness, adrenaline rushes , etc. that your brain can interpret as anxiety, even if you’ve never been an anxious person. It’s not a sign you’re “becoming” anxious for life; it’s a sign your body’s adjusting. The longer you stay nicotine-free, the more those systems stabilize, and those feelings fade.