> One study examining the sleep effects of 400 mg caffeine administered 30 minutes before bedtime demonstrated both severe sleep disruption as well as important cardiovascular effects during sleep likely related to increased sympathetic activity.
Going from 7.8 to 7 hours and taking 50 instead of 20 minutes to fall asleep is significant for the purposes of this study, but that's not what insomniacs and anxiety patients talk about. Insomniacs who lie awake until 4 in the morning and get 3 hours of sleep routinely because they're so worried by the cup of coffee they had or the supplement they forgot don't do so because they have a physiological reaction to some caffeine, it's a mental problem.
I'll need to see those studies. I'm finding the reverse: https://pmc.ncbi.nlm.nih.gov/articles/PMC3805807/
> One study examining the sleep effects of 400 mg caffeine administered 30 minutes before bedtime demonstrated both severe sleep disruption as well as important cardiovascular effects during sleep likely related to increased sympathetic activity.