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Comment by jadbox | Hacker News Reader

I have a wild pet theory that drinking caffeine consistently prevents people from dreaming. Antidoteally, people that I meet that avoid regular caffeine seem to report having dreams on a regular basis. Conversely, the people I know that drink a lot of caffeine seem to say that they never remember their dreams.

I've also noted today many people who take cannabis regularly also do not dream often.

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Personally speaking, both presence and intensity of dreams has almost a direct 1:1 correlation with how much I've learned or participated in mentally challenging tasks the day prior.

Most of the times I don't remember having dreamt are those when I've been more or less living on autopilot, with nothing novel in work or leisure time. Recently I've had an explosion of vivid dreams that lines up almost perfectly with doing things I'd not had prior experience with when programming in both work and hobby projects.

I've been on a pretty consistent one cup of coffee and occasional second cup over the course of the pandemic. The only way caffeine impacts my sleep is if I have it past 1-2PM, in which case I find it harder to fall asleep and may wake up periodically but will still dream.

It's well known that sleep-deprived people have shorter and fewer REM sleep periods. So, presumably sleep deprived-people likely have fewer dreams. That doesn't necessarily mean they'd remember fewer of them, but it wouldn't be a big stretch.

Personally, the amount of sleep I get correlates strongly with the amount that I remember dreams.

I suspect caffeine intake is correlated with sleep deprivation bidirectionally. People who don't have the free time to afford enough sleep tend to drink more caffeine to compensate, and people who drink more caffeine tend to have lower quality of sleep.

So, I suspect that it's the length of sleep that's really the relevant factor here.

I've also heard from several friends that nicotine patches cause very vivid dreams almost every night. Caffeine certainly isn't nicotine, but the case for stimulants in general causing a lack of dreams. Maybe caffeine is an outlier in this regard, but, like I said, I suspect caffeine intake is primarily a confounder for sleep deprivation.

Let me then be the first in your contradictory sample. I drink caffeine more than ever and have consistently been experiencing a higher number of vivid dreams in the past year or so.

Same here. I also find I have more vivid dreams if I'm dehydrated or hungover, do you find the same? (And to add another factor, do you drink alcohol?)

Alcohol suppreses REM sleep, resulting in a rebound effect. This can happen in the same night, resulting in more vivid and memorable dreams closer to morning when, for a number of reasons, we are more likely to remember them.

I drink caffeine but I don't drink it after 2:00 p.m. and have really good dreams sometimes.

"Having dreams" in this case would mean remembering dreams. You dream whenever you go into REM sleep, but remembering those dreams requires active training, since your mind is kind of designed to block all that out.

Oh, here's a fun one for you. Have a dream where in the dream you tell yourself you'll only remember this dream because you're about to get woken up. Then get woken up by something you had no control over moments later.

All I can assume is this is a pretty common thing I do in my deep sleep dreams and I don't happen to wake up to remember it.

Absolutely the point, you don't just stop dreaming. I had a period where I would actively make an effort to write down any dream right after waking up, and lo and behold I dreamt every night. Now that I've stopped doing that I remember maybe one or two dreams a month.

Not sure if you will read this but wanted to let you know that I found your theory intriguing and decided to cut caffeine to test.

First day light headache. Second day onward totally fine.

Dreams are back!! Not kidding at all. Over the last few days I’ve had much more vivid and sticking dreams. Some of them bad, but dreams nonetheless!

Thanks for putting forth this theory. I will be reducing my caffeine intake permanently. I beleive dreaming is a healthy part of being alive, and I’ve been missing it.

I don't think you can generalize from your experience. I drink tons of coffee and have wild dreams every night. They're even wilder on the rare occasions I smoke pot.

Conversely chronic chronic users rarely dream and there is a significant rebound effect with cessation of cannabis.

I'm not discounting the potential effect of substances on REM, and as a drinker I'm aware of the deficit during the first 4 hours of drunk sleep. But really, I don't think people are talking about dreaming here so much as the perception or recollection of dreaming. I've made a point of keeping a notepad next to my bed for about 10 years. If someone had asked me before that how often I dream, I would've said maybe once a week. I don't think keeping a journal actually made me dream any more often. It's just that once I really made it a habit to access the halfway state by jotting a note every time I woke up, I became aware that I have 3-4 crazy dreams every night. The only exception is drunken blackouts, but I'd lay odds that's because I just don't wake up often enough to write them down.

I think it is somewhat scientific at this point that cannabis prevents dreams (or at least the memory of them upon waking). And going off weed can lead to much more vivid dreams until one is once again acclimated to being weed-free.

I wonder if there's some sort of neurological catch-up that's being played while this occurs.

This feels like it could be true - I think dreams went to near zero for me around the time I started drinking coffee and tea consistently. But so much else in life was changing at the same time, it's hard to be sure.

Seems like an easy experiment then? Drop coffee and tea for a while and see if they return.

> I've also noted today many people who take cannabis regularly also do not dream often.

As someone who smokes weed I heard this as well. But from experience I still dream, just that its harder for me to remember them if at all.

Counter anecdote: my partner has been a coffe drinker since the age of 5, multiple a day, even right before bed (cultural norm is South Africa). She dreams a lot. Extremely vivid and remembers a lot.

Yeah I quit a few years ago and before quitting I very rarely had dreams. Now I have at least one dream every night. Also convinced a few people to quit and they reported the same thing.

Wow, I never made this connection but you’re right - about the time I quit coffee my dreams started again

Did you compensate for less caffeine by getting proper rest at night? Many people quit caffeine at the same time they resolve to get a proper amount of sleep. I suspect getting enough sleep is the causative factor and caffeine intake is a confounding variable.

N=1 counterexample:

I stopped drinking caffeine for a few years (maybe 3?) and have restarted also for a few years (probably 5 now) and I dream fairly rarely both when drinking caffeine and not.

I don't consume any caffeine, and I have extremely vivid dreams almost every night.

The other thing I've noticed is people who smoke a lot of weed seem to report a lack of dreams.

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