Do you mean it doesn’t affect their sleep? I remember the first time I tried coffee and the effect was profound, like my brain wasn’t working properly before that moment. I have also been diagnosed with ADHD, but I am affected by caffeine so maybe that’s a misdiagnosis. I also have huge variation over my life where I can sometimes handle 6+ cups without issue and other times half of a Diet Coke will send me spiraling into anxiety. It seems like it has to do with my stomach or baseline levels of anxiety, definitely worse after some sort of trauma. Maybe just a comorbidity that complicates things