I've actually been cutting out caffeine after listening to Michael Pollan talk about drugs and society on NPR.
Turns out the half life is typically long enough that using caffeine every day long term will lead to cognitive decline because of sleep deprivation. It's good for an occasional boost, but you're really burning the candle at both ends.
I'm off caffeine after many years of daily consumption. Took a few weeks, but my energy level is now about the same as it was before I quit and I no longer feel tired without it. I do quite miss the taste and ritual of tea and coffee, though.
80% of adults have caffeine intake in a given day. So what's more plausible, that 80% of adults have cognitive decline, or the author in question is full of crap?
Given the word "cognitive" was used I assume "cognitive decline" refers to some sort of scientific measurement like an IQ test. If 80% of the population is experiencing it that would be pretty easy to measure, I would think?
If we are just discussing whether human beings are awful... humans were being awful far before the popularization of coffee beans, so that seems like a red herring in general.
According to Pollan, for most people, there's still enough in your system to disrupt your natural sleep; your brain doesn't shut down enough to get a good rest. IIRC, he was discussing monitoring brain activity during sleep and you can see the difference between people who drank coffee that morning, and people who didn't. Caffeine has just about left your system completely around the time you wake up and start drinking it again, which usually isn't too long before you start getting caffeine withdrawal symptoms.
edit: half life for caffeine is 2-12[1] hours (most sources claim ~5), depending on the person. For a half life of 6 hours (using this because it's close to 5 and divides evenly into 24), you still have >1/8 of what you drank that morning in your system when you go to bed, and 1/16 when you wake up. Over the course of a lifetime, it's not hard to imagine that having a cumulative effect.
What is good rest? I get 80 minutes or more a night of deep sleep regardless of my morning caffeine intake. I almost always wake up well rested and still drink ~300mg of caffeine over the course of a day.
I didn't read the book, but from his interviews it sounds like all he did was gather N=1 over sufficient time to show it effects him. This is one case where I am going to have to appeal to authority. I have yet to see evidence your morning coffee is destroying your cognitive function. I have not experienced it either. Given my data is just as valid as his I would like to see actual controlled studies on this. In particular on the absolutely outlandish claim that 1/8th to 1/16th of the dose of caffeine remaining in your body does anything if you're consuming it only in the mornings.
I'm not a sleep researcher, so I'm not really qualified to say. I did poke around and find some papers on caffeine's affects on sleep, but there honestly wasn't (IMO) a huge amount a research, and what I did find mostly focused on caffeine intake less than 6 or 8 hours before sleep. Everything I found did see differences in brain activity or REM, but there seems to be room for interpretation on what those differences actually mean (turns out brains are really complicated).
I did find this though:
"Regular Caffeine Intake Delays REM Sleep Promotion and Attenuates Sleep Quality in Healthy Men"
>Our data indicate that besides acute intake, also regular daytime caffeine intake affects REM sleep regulation in men, such that it delays circadian REM sleep promotion when compared with placebo.
That looks like it, but I heard it in 2022 or 2023, might have been a re-run.
I can't listen to it right now, but I remember in the program he was talking about publishing some of his books describing his experiences with illegal substances and he had his publisher agree to pay all potential legal costs on top of paying his regular salary to his wife in case of incarceration.
Turns out the half life is typically long enough that using caffeine every day long term will lead to cognitive decline because of sleep deprivation. It's good for an occasional boost, but you're really burning the candle at both ends.