"If you are having trouble sleeping, cut back on your last cup of the day."
I wish! The older I get, the less caffeine I can have in any form, and the earlier in the day I have to quit drinking it. At this point, being 47, even a decaf (which has tiny amounts of caffeine; see https://www.webmd.com/diet/news/20061011/decaf-coffee-isnt-c...) coffee after 10 a.m. affects my sleep.
My anecdote is that coffee definitely has something besides caffeine that affects the central nervous system. I tend to quit drinking coffee few times a year, and I replace it with heavy tea drinking.
No amount of tea makes the withdrawal symptoms go away. After a week, the physical effects (headache, tiredness) thankfully fade, but nothing seems to help with the depression that comes in a month. Due to that, I haven't really gone beyond a month of not using coffee -- it just doesn't seem worth it.
I would find the people who think that coffee is not a narcotic amusing if they weren't so fucking serious. I really wish there was more scientific data on this. Seems like all studies just focus on the caffeine effects.
I wish! The older I get, the less caffeine I can have in any form, and the earlier in the day I have to quit drinking it. At this point, being 47, even a decaf (which has tiny amounts of caffeine; see https://www.webmd.com/diet/news/20061011/decaf-coffee-isnt-c...) coffee after 10 a.m. affects my sleep.