Yeah you're right. This of course differs from person to person. I was thinking about this article actually: https://www.theguardian.com/food/2021/jul/06/caffe

Yeah you're right. This of course differs from person to person. I was thinking about this article actually: https://www.theguardian.com/food/2021/jul/06/caffeine-coffee-tea-invisible-addiction-is-it-time-to-give-up https://www.theguardian.com/food/2021/jul/06/caffeine-coffee... > In fact, none of the sleep researchers or experts on circadian rhythms I interviewed for this story use caffeine. > Walker explained that, for most people, the “quarter life” of caffeine is usually about 12 hours, meaning that 25% of the caffeine in a cup of coffee consumed at noon is still circulating in your brain when you go to bed at midnight. That could well be enough to completely wreck your deep sleep. > I thought of myself as a pretty good sleeper before I met Walker. At lunch he probed me about my sleep habits. I told him I usually get a solid seven hours, fall asleep easily, dream most nights. > “How many times a night do you wake up?” he asked. I’m up three or four times a night (usually to pee), but I almost always fall right back to sleep. > He nodded gravely. “That’s really not good, all those interruptions. Sleep quality is just as important as sleep quantity.” The interruptions were undermining the amount of “deep” or “slow wave” sleep I was getting, something above and beyond the REM sleep I had always thought was the measure of a good night’s rest. But it seems that deep sleep is just as important to our health, and the amount we get tends to decline with age. It seems to argue that at night, the remaining caffeine in your system is not enough to be effective, but enough to hurt your sleep quality.