There's no definitive study that I'm aware of, but anecdotally many people have trouble getting to sleep if they consume caffeine too late in the day, and/or struggle to get out of bed before regularly consuming caffeine in the morning.

Part of being feeling tired in the morning can actually be caffeine withdrawal symptoms. You start off in a low and need your fix to get back to normal. Once you get off of it, that normal becomes your normal again.

I was 2-5 cups/day drinker for years. I tapered down my intake over a month, but the first couple weeks of no caffeine was hard. I'd guess it took months before I really felt free.

I drink decaf most days now. When I have the occasional cup of real coffee ( 4 times a year), it gives me a good boost.

For me, my sleep quality noticeably improved ober night after I stopped all caffeine. I had headaches for about 2 days, then slept the best I had in years. I wasn't a big coffee drinker. 2 cups with breakfast, maybe a black tea or 2 in the day, nothing after about 4pm. But it was obviously still in my system at night.