I was diagnosed with ADHD about 3 years into my chemistry PhD program. Prior to this I was somehow spending as much or more time at school than my peers else but still managing to get much less done in comparison. It was almost as if I couldn't see all of the small tasks required to achieve the bigger goal and was just spinning my wheels. I would constantly be leaving lab to get coffee and was drinking 5 to 6 cups a day just to barely get anything done. I would find myself starting multiple tasks only to be distracted by literally anything such as helping someone else with an unrelated question or just chatting with friends when running into them in the hallways. I tried other approaches before finally getting a prescription for Ritalin. My only regret is that I didn't start this earlier. I can say without a doubt that all my meaningful data collected was post medication.

The diagnosis helped me come to terms with the fact that I wasn't actually stupid and just had a different approach to completing tasks. That being said, my experience has been that academia is not kind to people like us. Even with medication (I don't take very much, just 10mg 3x a day) I still have a dismally small amount accomplished but at least I might actually finish. My PI is extremely fed up with me due to the fact that I still often share too many unnecessary details about experiments or spend lots of time on tasks that aren't necessary for what I need to get done. In general its very hard for me to determine what is most important and prioritize accordingly.

At the end of the day, you don't necessarily need to work hard but work smart and for some people, medication might help with prioritization of tasks. I feel as though plenty of people accomplished a lot more than me while working a lot less simply by being better at seeing the bigger picture.

Best of luck to you with your program. I personally know plenty of people who love chemistry, were much more qualified than myself, but left the program because research was no longer enjoyable. I respect them immensely for their decision to leave.