The only consistent effect I've observed is that the first cup of the day jump starts things in the digestive department and brings on a trip to the bathroom with some haste, but I've suffered on and off with IBS-like symptoms over the years anyway—even before I started drinking coffee.
In my early and mid-twenties I'd drink 5-6 cups of black coffee a day at work. I noticed no ill effects or really any effects at all—no crashes, no jitters, but also no increased alertness or focus.
I now usually make myself one latte in the morning then an additional one or two black coffees through the day, but I can still drink a coffee right before bed with no noticeable effect on getting to sleep. I don't usually have any coffee at the weekend, because Saturday I take my machine apart for cleaning, and Sunday I'm typically out of the house at the times I would normally make one. If I go away on holiday somewhere I might go a full week without any coffee at all, again with no noticeable effect.
Unfortunately I can't honestly say I have good sleep, because even now (I'm 31) my natural sleep schedule still wants to be something like 3am-11am, but society doesn't tolerate that. I really hoped that would be something I'd grow out of, but I haven't. So I'm pretty much tired all the time whether I drink coffee or I don't.
I was diagnosed with ADHD as a kid, never medicated for it. Just regulated with diet and exercise, also probably self-medicated with caffeine and nicotine in college. Quit nicotine because of the very obvious health problems that come with it, I found it very easy to quit interestingly enough (thank God I quit before the Zyndemic).
But I have never felt that coffee comes with any negative side effects for me other than anxiety. It doesn't affect my sleep unless I drink it past 5 PM, and I've never felt like it "wakes me up", it just lets me enter a hyperfocus state a lot more easily. Other people describe their relationship with coffee that they wake up and feel groggy, so they take coffee to have a baseline. For me it has never been about waking up, it's just something that helps with focus.
I do get the jitters when drinking coffee especially since I eat my first meal very late in the day (12pm), so I switched to mate cocido, which is just mate in tea bags. The effect of even very strongly-brewed mate is far less pronounced than the effect of coffee, and I would even go so far as to say that whatever benefits I think I am getting from mate is probably just placebo.
For reference during college I probably consumed 3-4 cups of coffee a day, then as I started working I would consume 5-6 cups a day, black. Now I stop drinking coffee after I eat at noon, so I am down to 2-3 cups a day.
Also I think that brewing methods matter. Hot-brewed coffee causes less jitters and more focus. Cold-brewed coffee tastes better but it is easy to overshoot what feels like a "therapeutic dose" and actually end up making it harder to focus, as well as more jitters. It might be that I usually have hot coffee black, and I have cold brew with a bit of milk and simple syrup. The sugar or coldness might also make me colder or do something with my blood sugar, not sure.
I drink all black espresso first thing in the morning, with the highest or mid intensity. Drink one in the morning, one in the afternoon, a small amount in the evening. I still sleep very well at night.
Now I am almost 40 and in my country people always ask me why I look so young for my age. I always tell them, it’s just coffee. I don’t consume alcohol or smoke, it’s just caffeine. I’ve been on this caffeine binge since I was in high school.
Ok maybe it could be plenty for some people, but for me 4 cups a day would be plenty lol.
Maybe caffeine doesn't affect me much to this point and that's why I don't have any problem sleeping. I doze off 10' after putting my head on the pillow.
Now regarding stress... comparing myself to the people around me I'd say I have normal levels of it. But most of those people consume caffeine daily so it's hard to have an objective measure.
I'd like to carry out the experiment of going 15 days without caffeine to see if stress decreases though but it would be very hard considering how ingrained the substance is in our lives, even the social aspect. Mate for example is a drink which we usually share here in Argentina. You could maybe call it a ritual and a way of social bonding. And I like how it tastes too, of course. Add that to all the times you meet with people "for a coffee and chat", for example.
Alcohol is similar; many people seem to equate any level of consumption of — or even interest in — alcohol with alcoholism. I enjoy alcoholic drinks, mainly for the taste, but can’t imagine becoming dependent on it. I think it must be a genetic thing. ‘Giving up’ alcohol for me would be a net decrease in quality of life; for me there’s no temptation to abuse whatsoever.
I used to drink about a litre of brewed coffee a day, starting at 7AM and going on until 5PM. Eventually that fell away, without any decision on my part, and I now drink one mug a day (1/2 imperial pint), after getting up.
It doesn't seem to power me up or make me more alert; I think it actually makes me dozy, 2-3 hours after my morning joe. That is, I think I only notice the crash.
I'm confused by the anti coffee crowd. By all accounts black coffee is a healthy drink with essentially no calories.
If I skip a couple cups I will get a headache, it's very predictable.
it is noticeable if i don’t have a cup at least at some point during the day but there are plenty of days i don’t have as much or hardly at all. but i just like the warmth and how it tastes, the caffeine is a non factor if i decide to have a cup or not.
other things that are probably significant factors: low stress job at a small private company where i don’t really have hard deadlines or deliverables and WFH as much as i want; wife and pets but no kids; low stress otherwise is areas of my life
No problems sleeping, and stress seems average for the job lol
Honestly, I'm not sure if coffee even helps to "stimulate" me at all. It certainly lowers the feeling of stress and helps me keep a clear train of thought, though, even if that may be placebo effect. And it's something else than water to drink.