Why does coffee make me sleepy?

15 October 2013


Why is it that when I drink coffee it can make me more sleepy? Other people seem to drink coffee and wake up!


We posed this question to the brain panel...

Mike - It depends on the time course. I'd be surprised if somebody would drink a cup of coffee then immediately feels sleepy. But I think it's perfectly reasonable to feel sleepy a little bit later on because, what's happening when you drink coffee, is that caffeine blocks the action of a "tiredness transmitter" in the brain called adenosine.

Adenosine progressively damps down brain activity as it accumulates during the day, contributing to sleepiness. When we go to sleep, the adenosine is flushed out from the brain again so that we feel rested and refreshed when we wake up.

If you block the effect of adenosine with caffeine, then you will feel more awake. But, later on, when the coffee effect wears off after it gets eliminated, which takes 4 hours or so, the adenosine is still there, and then that may kick in and make you feel sleepy. But I don't know of a circumstances where you would drink coffee and then suddenly feel sleepy.

Bill - Except, perhaps, if you had a strong association with coffee as a thing that you took next to going to sleep. Like children hear nursery melodies and they're put to sleep by it. If you had a routine in which you drank coffee and then went to sleep, it may be a signal to sleep and would help you get to sleep. Is that possible?

Hannah - Or maybe he associates coffee with incredibly boring activities like being in the office?

Katie - Feeling really tired?


Most of the coffee and caffeine seems to be poisoned with something to tranquilize people and knock them out cold as soon as they drink it. One cup of this "bad" coffee and I sleep for hours. Anyone who claims this stuff isn't drugged is delusional. It is undrinkable except as a tranquilizer at night if you can't sleep. The stuff is drugged somehow. I think they're contaminating it with some kind of cleaner or something that turns into GHB. Plausible deniability. There is tons of the bad stuff. I think it's supposed to wake people up just in a different way. Every Starbucks Kcup I've had that I got for Christmas has made me sleep for 2-4 hours. I've had the same thing at McDonalds, picked up a cup on the road to wake up and started to fall asleep almost immediately. Nestle instant too good batches and tranquilized batches. Like someone slipped me a mickey. It has nothing to do with the brand it seems to be all brands, but not all coffee from any brand. Just most of it. I am convinced it's being poisoned intentionally by religious cults or as a political act of some kind.
People who truly need it can't get amphetamine to function, why should you be allowed to take caffeine to function better when you don't need it? This is how the government and the religious cults that run it make sure you're not addicts and they're not feloniously fostering an addiction. Opiates, you need opiates, tranquilized pigs don't squeal as much when slaughtered. Lifespan just declined again, praise Jesus, the govt. and the Obama financed AMA for protecting our health by murdering us. Don't think the ABA is going to protect you from the AMA and the DEA, they've been financed by the drug war since before the govt. started providing free legal services to the poor. Coffee in Europe never has this effect. Why?

I used to drink a lot of caffeine, like 5 coffee a day or two red bulls an drew then I quit coffee totally and cut down on energy drinks to only days when I get no sleep. Recently I started drinking coffee again and it immediately knocks me out faster than a sleeping pill. I suspect our bodies have gotten bombarded with it for so long that they have a built in immediate response to counteract the caffeine effects maybe?

There is something there. Since I awoke this morning, I've had three large cups of coffee, and 160 mgs of caffeine in an energy drink. I can barely keep my eyes open.

I farm and sit on equipment for many hours at a time. I can not drink coffee during these long days or I will fall asleep while operating equipment. If I can not sleep very well. I can make a cup of coffee to put me to sleep. Do not even have to finish the cup. Like warm milk for some people.

I drink at least a few cups of of coffee in the morning every day, and it wakes me up. Later in the day though, it tends to make me tired, often times so tired that I can't help but fall asleep, before I even finish the cup of coffee. As a matter of fact, it just happened and I just woke up to a half cup of cold coffee. It happens even if it seems I got plenty of sleep the night before. I've found that cold coffee drinks- iced coffee, canned coffee drinks like Starbucks- don't make me tired at all, and doesn't matter if they have sugar in them or not.

I am not a big coffee drinker,I prefer tea mostly, but the minute I have my daily cup of espresso with dinner, I fall asleep. Why?

I love coffee but I feel I have to push myself to move or on lazy days will allow myself to go lay down since it's difficult to keep my eyes open. Differently from previous comments, however, I have a low metabolism & take .112mg of levothyroxine daily.

I've had 6 shots of espresso this morning so far, 2 at a time with a bit of milk, over the course of about 75 to 80 minutes and I want to go back to bed. Got plenty of sleep last night too. Happens every day. Doesn't matter if it's coffee or espresso (or coffee with espresso), hot or iced, black or with a bit of milk. I'm always sleepy, immediately. I have Early Onset Parkinson's so I've always wondered if there were a dopamine connection.

I can drink a cup of coffee thinking yes, this will help me clean my house. Only to finish a cup and feel so weak and tired I can't even stand. I have to lay down and sleep. What's the deal with this. It's real it happens please someone out there study this. It all happens to me within minutes of injesting coffee. I'm not a daily drinker. Never have been for this reason. I never drink more then a half a cup. So....anyone??

If it happens particularly with coffee or black tea in strong doses, then it can be a mild intolerance to one of the many compounds in these brews that's making your body react defensively therefore making you weak in a matter of minutes up to the first few hours, especially if it was on an empty stomach and drank quickly. Consult your GP if you think it might be this, because it's fixable. Intolerances come and go, it can depend on factors like diet and hormones. Although dehydration is also a thing.

I say this because it actually happens to me, with both coffee and black tea. But then if get a boost from energy drinks, like a couple of 80mg caffeine redbull (morning coffees are about 100-200mg caffeine) I won't feel sick and weak, although I'll feel the dreadful caffeine crash of low tolerance around 3 hours after drinking it quickly on empty stomach. The crash feels awful but only lasts about an hour and then energy magically comes back and stays higher than previous to ingestion for the rest of the day, which didn't happen with coffee/tea.

Finally I've also been trying recently caffeine in capsule form, in particular combination of caffeine 100mg and L-theanine 250mg, and must say this is BY FAR the best option, with all the benefits from natural caffeine forms, and almost none of the drawbacks. It kicks in very smoothly but intensely, it doesn't "hit you like a train" like coffee does, but it progressively clears up your mind. The theanine improves concentration, relaxation and completely removes the common coffee jitters.
Oh and also, thanks to theanine there is NO crash at all! This stuff is amazing.

I get sleepy with those 5 hour energy shots as well. For some possible insight, take a look at how adderall effects people with ADD. Adderall is a stimulant and makes normal people wired, but calms down people with ADD.

Curious if you have problems thinking sometimes or need dead silence to be able to think, thats a sign of ADD.

Same here for us to all be looking on the internet for an answer There has to be an issue.I drink coffee and half way im ready to go back to bed.I love coffee the smell,taste so whats up?

I feel sleepy after drinking coffee and I wonderif it has to do with my quick metabolism. If you look at the first answer given by Mike, could it be possible that this process happens much faster in some people than others? So the dehydration would set in quicker and cause sleepyness... Just a thought.

I totally agree. Coffee can make you fall asleep if youre already kinda fatigued, or thinking of going to bed. Maybe it also has something to do with a quick metabolism too- or maybe just the milk you add.. I find coffee does help for sleep while tea, or ice* coffee actually has slightly opposite affect. Interesting...

I am not a big coffee drinker nor do i drink them on the regular. I can literally drink a cup of coffee and go to sleep. Its been that way all my life. Cokes or energy drinks dont keep me awake either. I heard you develop a high tolerance of it after a while but how can i develop it if i dont drink it.

Nobody believes be when I tell them I could drink coffee or coke before bed and fall right asleep.
I have done it many times. In fact the only time I feel the effects of caffeine is when I overdose.
Today in particular I drank a cup of coffee and I haven't gotten out of this chair yet because I feel so sedated.
I came here looking for answers to what happens differently in my body with caffeine.

I'm 23 and every time i have tried coffee no matter where it was, at school, an important event i needed to stay awake for or my friends house i have fallen asleep within 20 minutes and i will stay asleep for around 16 hours. Coffee to me is like strong sleeping pills. So many people drink coffee so it comes up in my daily life alot. Every time i tell someone "i dont drink coffee because it puts me to sleep" they ask me if i have ADHD. Which i dont know. Is this something that only happens to me?

Hi - This also happens to me sometimes. Most of the time I can drink coffee and it will keep me awake, even hours later. But sometimes - especially when drinking coffee at a diner - I will get immediately drowsy and if it is a day off, I fall asleep within about half an hour and will sleep for an hour or so. So, like the 2 ladies before me, I'm not talking about coffee in the morning and then a crash in the afternoon - there's something about the coffee that makes me sleepy. My own hypothesis is that the particular batch has less caffeine in it, and the "hot milk" from the cream I put in it makes me drowsy.... But I don't think this is so because it often happens (BUT NOT ALWAYS) after drinking it in a restaurant and putting that fake cream in it, which is all most places seem to offer any more. It seems like there's no simple answer for this apparently common phenomenon.

I can drink two 20ounce cups of coffee in the morning, I put ice in it directly so it won't be so hot, but I can lay down as soon as I finish my second cup , and that's usually around 5:30 or 6:00 am and go right to sleep.im not sure why or how, but I'll prove it to anyone that wants to see.

Coffee definitely makes me sleepy, not 4 hours later, immediately after I finish a cup. By sleepy, I mean, I'm likely to go to sleep, if I'm not working and it's my free time. I've been drinking about 5 cups of coffee a day for my whole life, maybe that's the reason. Would love to know why.

When I drink coffee (doesn't matter how it's made or what's in it), I immediately feel a headache coming on and then get very tired. I once fell asleep while in college after I drank a large cup from Starbucks with the intention of staying awake. I wonder why it affects me so differently.

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