I might be able to add several points to this discussion: - For me, caffeine has really bad impact on my sleep quality, and it is an accumulative effect: After being abstinent for 1-2 weeks, I can drink 2 cups of coffee in the morning, and I will have good sleep. After 1-3 days of daily 2 cups of coffee, my sleep quality goes down - Most research about safety of coffee is done with young, healthy adults w/o any medical preconditions. Which translates to, everything found in the research is objectively true, still it totally cannot apply to your, your health and life circumstances - Finally, I observe people around me which can tolerate higher amounts of caffeine w/o any side effects. To the best of my knowledge there are very individual tolerance levels for caffeine and also very individual metabolization speeds

tldr: - caffeine is known to increase anxiety, heart rate and disturb sleep - YMMV and it even might vary depending on your age, phase of life, other activities - if you observe feeling stressed, problems with sleeping or winding down, try to avoid caffeine/alcohol/etc. for a few weeks and observe if you feel better