How Much Caffeine Is Too Much? | Hacker News Reader

How Much Caffeine Is Too Much?

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I went to the ER (https://twitter.com/jprichardson/status/522084579906052096) about 2.5 weeks ago because I didn't get enough sleep and drank way too much caffeine. My body just collapsed.

From October 5th through October 11th, I actively rejected sleep (2 - 4 hours of sleep) and took in quantities of caffeine ranging from 1.5 g to 2 g. (A cup of coffee has approx 100 mg and a strong energy drink has about 250 mg). I was preparing for launch of my product and subsequent YC application. On Saturday morning, October 11th, I had massive chest pains and I collapsed. Fortunately, everything is alright with my heart. Overall though, I felt incredibly stupid about my actions.

As hackers and entrepreneurs, it's really easy to fall into the trap of your launch being the most important thing in the world. It's not. You need to be healthy, as business is a marathon and you'll be running for awhile.

When you collapsed, we're you also sleeping?

No, I was standing up.

Edit:

I'm not sure. Doctors didn't comment much on it, so unfortunately, I don't have a conclusive answer. But it does seem plausible that my body decided to override my willpower and decided to "shutdown".

I think OP was asking if you perhaps collapsed because you fell asleep on your feet. Or not.

I think you're right, that makes much more sense. Haha. Revised answer.

Sounds really scary.

You should write up a PSA blog post about it.

Definitely plan on doing this. I think it's incredibly important for people to realize that you can't make health your last priority - not if you want to build a sustainable business. I had warning signs leading up until that moment that I foolishly ignored. I can't be the only one that has experienced this and if a blog post can make at least one person reconsider their behavior and save them or their family from trauma, it would be worth it.

For what it's worth, I saw the same thing happen to a coworker with essentially the same circumstances. The doctors basically called it exhaustion.

> A cup of coffee has approx 100 mg and a strong energy drink has about 250 mg

That's a _very_ strong energy drink too, most are in the 140-160mg range in my experience. Less caffeine than a large at a major coffee joint.

Holy crap though, that's crazy. Over what time period did you consume that much caffeine? Do you mean daily or over the full 5th-11th period?

That caffeine intake was daily.

My poison of choice was Rockstar Pure Zero - Mango Orange Passion Fruit. They originally launched with 160 mg per can, but bumped it to 240 mg. http://www.caffeineinformer.com/caffeine-content/rockstar-pu...

Like I said, not one of my brighter moments - I was just willing to do whatever it took to launch. In hindsight, not worth it at all.

As someone who experiments with nootropics, I highly recommend modafinil over caffeine for sprints like that (up to 36 hours of wakefulness at a time, no jittery feeling, etc). You should not do it for any appreciable amount of time though. See https://reddit.com/r/nootropics for more info.

Modafinil is much more expensive, harder to get, and not everybody responds to it.

I once watched three engineers take Modafinil for an all-nighter. It was their first time taking it.

By about midnight none of the engineers felt any different. One of them decided it wasn't doing anything and went to bed. The other two decided to keep hacking until they got tired.

Come morning the two guys who kept hacking were still hacking. The third guy said he slept soundly. The two guys who kept working said that, while the Modafinil never made them feel different, neither were they particularly sleepy. Exhausted, yes, but not sleepy.

The guy who decided to go to sleep used Modafinil after that and it worked as advertised. He just needed to realize that it wasn't going to make him feel stimulated.

I know that at least one paper shows efficacy dependent on certain alleles. But AFAIK none say that it doesn't work at all. And the majority of people have the alleles where Modafinil works well.

Compared with OD-ing on caffeine or other stimulants, I'd say Modafinil is the better choice. There's no substitute for sleep, and unlike normal stimulants you can usually deliberately go to sleep even after taking a full dose of Modafinl. Which means you can use your time more efficiently during a marathon and still get some proper rest.

Modafinil, while a bit more expensive than caffeine in pill form, is easily available online without a prescription.

You're correct.

There's lot of confusion here over beverage sizes.

240mg in a 16oz/473ml can. It also seems to have been reduced back to 160mg.

Even at 240mg it's equivalent to or less than a cup of medium strength regular coffee. And not close to Espresso.

The problem is, it's much easier to drink down sugary beverages than coffee(especially hot).

> 240mg in a 16oz/473ml can. It also seems to have been reduced back to 160mg.

A few of the "Pure Zero" variants seem to have (or had) a ludicrous quantity of caffeine. If I have any complaint (well, other than that a 16oz can doesn't have 2 servings worth!) it's that I don't know that the caffeine should really differ between them; one might not expect what seems to be simply a different flavor to differ markedly. My solution to that has been to read the ingredients.

> Even at 240mg it's equivalent to or less than a cup of medium strength regular coffee. And not close to Espresso.

Coffee varies but generally speaking if one goes by the "serving size" on an energy drink it's typically on par with coffee: http://www.reddit.com/r/askscience/comments/ip9ia/ive_been_w...

My choice was the regular Rockstar energy drink at my worst I was up to the large 750ml cans per day, then suddenly I developed back spasms for the first time in my life I thought it was a kidney stone. I could not straighten up I was curved to my right as if I was made of stone, the only thing that helped were strong muscle relaxers.

I stopped for awhile and drank just the normal ("double" is normal) Rockstar. I felt tingly all over mostly extremities. Now I have a fatty liver I am sure caused by energy drinks, I haven't had one in at least three years.

Coffee and tea are no comparison to energy drinks even a four or six shot espresso is mild in comparison. Although I believe espresso has less caffeine than regular coffee even for equal volumes.

What's odd is I never drank any caffeine until I was about 34 since even a sip affected me making my heart race from just a sip.

I've now left the stupid energy drink drinkers club!

//Although I believe espresso has less caffeine than regular coffee even for equal volumes. //

This is a common confusion. Espresso has more caffeine by volume.

Looking at ~8oz/236ml cup of 'regular' coffee versus ~1oz/29ml shot of espresso.

Check your math:

That's 236ml of caffeine for 8oz of coffee and 232ml of caffeine for espresso. That's less caffeine in espresso than coffee by volume.

According to Google (which cites USDA) for "espresso caffeine" and "coffee caffeine", there is 64 mg of caffeine in 1 fl oz of espresso and 94 mg of caffeine in 8 fl oz of coffee.

So per unit volume, the espresso has several times the caffeine (and you would already expect a double espresso to have more total caffeine than a modest sized drip coffee).

My math's fine. I think you misunderstood my post. I was just considering metric and imperial sizes thus included both sets of units.

The first reply to your post shows the math.

Even the 'increased' 240mg in the energy drink is just equivalent to 'regular' coffee due to it being 16oz/473mL can.

As I said though. Much easier to gulp down half a litre of sugary soda than half a litre of oily thick espresso.

I did misunderstand it, my apologies.

I suspect there are something else in energy drinks that could have dramatic effects on one's brain.

I usually drink one or two cups of coffee per day. I could drink more. After 7~8 cups of espresso, my hands start uncontrollably shaking, and I feel a little agitated. Those are all the symptoms I feel. Energy drinks is a completely different story. After two cans, I would have a big headache. I experimented a few times [call me crazy :)]. Every time, the headache came. So it was not a fluke, and most probably it was not caused by other factors.

> My choice was the regular Rockstar energy drink[...] fatty liver

Should've gone with the Rockstar Recovery. It's got milk thistle :)

Not to mention no sugar, which I suspect is the worst thing most people can get out of just grabbing a standard energy drink.

Uh, days of sleep deprivation + lots of caffeine is recipe for disaster. I have read about people getting heart attacks from that kind of combination if you take it to extremes.

A similar thing actually happened to me - I wound up triggering a hemiplegic migraine, something I'd never experienced before. Unable to talk, focus my left eye, or feel anything on the left side of my body. Probably days of marathon coding along with dozens and dozens of Red Bulls.

To this day, I still get pretty nervous anytime I lean on an arm and it falls asleep or I get any tingling.

Glad you're okay, friend.

Just jacking up caffeine intake isn't the way to go. Add in 200mg of L-Tyrosine for every 100mg of caffeine. Look into compounds in the 'racetam' family which have proven to be effective at improving attention and memory. Be sure to take some choline (Alpha GCP seems good) along with any racetam, especially if you get headaches from the racetams, they can cause your brain to eat up choline. Nootropics is an interesting field, and if you're willing to turn yourself into a lab rat (you are anyway, so I guess its just a choice to be conscious of it), there are certainly better ways to improve functioning. Also, 5 Hour Energy drinks seem to be pretty good. A little bit of caffeine and a big dose of B vitamins.

Try taking L-Theanine with the caffeine if you're going to take that much because it will help with dependence and adrenal fatigue. And frankly, I would take a much smaller dose, and generally never take more than 300-400 mg per day. I think you need something that works in a different way than coffee, as the parent to my comment says, look into nootropics. Reddit.com/r/nootropics/faq is a good place to start.

L-Theanine also seems to improve the effect of caffeine in me; the caffeine makes me alert, but the theanine with it feels like my focus can't be broken unless I want it to.

I did nearly the same several years ago. Went a few days with little to no sleep, drank a bunch of huge energy drinks, and ended up in the hospital with tachycardia. No lasting damage, but I've definitely been more careful ever since.

My first year in college I had a french press (a kind of coffee maker) and a tin of breath mints that had caffeine in them. One night, trying to finish a project, I drank an entire quart of strongly brewed coffee (~500mg)and ate the caffeinated breath mints like popcorn (30mg each)[0]. I recall walking down the dormitory hallways with extremely heightened senses. I was hearing whispers on the other side of closed doors and watching a fly buzz past me in what seemed like slow motion. I could feel the carpet texture through the soles of my shoes and time seemed to slow down.

At the time I thought it was one of the most incredible experiences of my life and vowed to repeat it sometime.

Thinking back I realize I was probably experiencing mild hallucinations and could have been on the verge of collapse.

edit: Added caffeine estimates.

[0]Can't believe I found this. http://www.wegotcoffee.com/mints/zingo.php

I know this feeling exactly. I one time consumed 2.5g of caffeine on a very VERY stupid dare.

Me and another kid were trying to bluster each other and each were one-upping the other, though we had a hard limit of 3g. He had 2g and started crying, shaking, and rolled up in the fetal position. In retrospect we should have taken him to the hospital, but he was fine.

The experience reminds me a lot of the movie Donnie Darko mixed with the futurama episode of Fry drinking 200 cups of coffee; it felt like you could see the animus of someone being projected into the future, and everything was practically at a standstill (like the time I was in a car accident).

We had a few pick up games of various games at this LAN we were at while doing this, and I won every one of them having to do with twitch speed even if the person had 5 yrs experience on me in a game and I had never played it before.

Not something I would repeat voluntarily, but it was an interesting experience.

It's still one of the most memorable experiences of my life. It was very similar to the reaction you get when in physical danger. I skidded half way down an icy ravine while skiing. I'm sure it took all of 10 seconds but It felt like 10 minutes.

There's an episode of Futurama where Fry drinks 100 cups of coffee, and experiences similar hightened sensations: http://en.wikipedia.org/wiki/Three_Hundred_Big_Boys

I refer to that experience as going "trans-dimensional" while the senses are heightened the mind/body split seems to be much larger and time is definitely not monotonic.

Same, 2-3 french press carafe 1/3 to 1/2 full of fresh ground coffee at the rate of one carafe per hour.

While traveling take caffeine pills to stave off headaches since the coffee routine as been disrupted.

"while the senses are heightened the mind/body split seems to be much larger "

Exactly this. I remember feeling like I was looking down on myself from just above the top of my head. I had an acute awareness of "seeing" my whole body, not just my arms, feet and the tip of my nose like a typical first person perspective.

To me it is like wearing a mask and playing puppet master with ones own body.

Caffeine withdrawal is not what causes the headaches from coffee cessation. It's something else (so far as I know unknown) in coffee that causes that.

my extra strength placebos are doing there job, don't Jones my fix.

Typically people get mild auditory hallucinations after they've been awake for 30 hours or so. Sounds like what you might have been experiencing.

Though the article does not take into an account the possibility that some may consume caffeine in powder form. You can find 100 grams, or over 7 times the lethal dose, for 13 bucks in Amazon [1].

As for who would use caffeine in such form are weightlifters and people interested in nootropics in general. I follow both communities online and from time to time I find some people overdosing caffeine by mistaking it to some other similar looking substance, like creatine or taurine. Though typical overdose has been about 3 grams, it has been enough to make the consumers force themselves to puke it out or get into ER.

I havent personally bought caffeine in pure form, but the idea has crossed my mind few times as these articles have started to pop out. I would not be surprised if caffeine would sooner or later be banned from being sold online.

[1] http://www.amazon.com/BulkSupplements-Pure-Alanine-Powder-gr...

EDIT: tried to simplify few sentences

I worked for an e-commerce retailer focusing on gifts for a time, during my stint we came upon a style of breathmint that contained caffiene.

they were pretty potent and they worked, but they had a warning on the side which said "do not exceed 2 mints in 6 hours"

Some guy had 12 mints at 80mg of caffiene each, promptly had a heart attack- we never sold the mints.

http://www.dailymail.co.uk/news/article-2453928/John-Jackson...

I recall seeing same kind of products in my local grocery store, just a few years ago. Though after most chains prohibited energy drinks from under 16 year olds, I haven't seen them since.

Yeah, with that (kids) in mind, high-dosage caffeine products shouldn't be sold over-the-counter like that; caffeine is seen as a harmless recreational product, but not in those doses.

In addition it can be used to train birds (falcons)...

Intrigued, Care to share more? A link?

Beta Alanine and Caffeine are quite different.

I wrote an article a while back about how to safely use powdered caffeine: http://diysupplements.com/add-caffeine-to-everything/

It's a great way to inexpensively measure exactly how much you're consuming.

I hope they don't ban it. Certainly people can make mistakes, but being able to buy caffeine in powdered form means you can create your own capsules and combine it with other things rather than having to just accept whatever other ingredients or binders, not to mention price markup, manufacturers decide to force on customers.

Apparently, caffeine makes it harder to intake iron.

http://fscn.cfans.umn.edu/prod/groups/cfans/@pub/@cfans/@fsc...

And anaemia, stemming from lack of iron, leads to fatigue and irritability, which both suck balls for coding.

edit: What did we learn in the article?

1. 140 cups will kill me.

2. Up to six cups a day will result in higher or lower mortality, depending on the study.

3. A study has shown that caffeine may lead to higher bad cholesterol.

> And anaemia, stemming from lack of iron, leads to fatigue and irritability, which both suck balls for coding.

What if you take vitamins & minerals?

My bias tells me that it's probably better to eat a healthy varied diet; get exercise; expose yourself to a bit of direct sunlight (10 minutes per day) but not too much; have good sleep hygiene; have good work habits; and so on.

These steps build resiliance against mild mental health problems and increase physical health.

I don't have any evidence and I especially don't want to be judgemental about it.

This is a direct benefit of coffee (along with donating blood) in my book.

The chances of you developing anaemia because of coffee are dim.

I'll drink six cups a day and find out which study is right.

Lack of iron is a serious problem, but many people (particularly men) may have too much (even if they don't have hemochromatosis). Iron depletion has been hypothesized as the reason that blood donation may be good for your heart, although the evidence is still inconclusive. At the very least, it's not something everyone needs to be concerned about.

Random biased selection of sources:

http://www.ncbi.nlm.nih.gov/pubmed/12430669 - A historical cohort study of the effect of lowering body iron through blood donation on incident cardiac events.

http://www.ncbi.nlm.nih.gov/pubmed/18619522 - Iron in arterial plaque: modifiable risk factor for atherosclerosis.

This article doesn't make it clear, but caffeine isn't the thing in coffee that raises cholesterol. That's cafestol, and it's captured by paper filters. So coffee made with a standard auto-dripper, or by pourover, don't have that.

As an avid french press user, I have to shove my head the sand every time I see this.

What's the use of a longer life if you can't have coffee the way you enjoy it?

Get thee an Aeropress. Cheap, paper filters, 5 second cleanup, silly delicious output.

The phrase "I can't go back to drip, french press is so smooth" will seem laughable. :)

Agreed, never going back to french press.

I just wish that I could make more coffee at a time with it, but I understand why I can't.

It's astounding how smooth aeropress coffee is, though.

Compared to french press, any filtered coffee is going to be smooth. I recommend you look into manual pourover brewers. The Chemex (my daily brewer) comes in sizes up 50oz.

I don't have anemia, but simply low iron (around 20 in ferritin level, recently it been up to 50), and I did read that coffee had an impact on low iron, and I do start believe this might be my problem.

I don't know the exact levels, but I was diagnosed with low iron in my teen years. The same span of time where I was obsessing over MMOs and mountain dew / red bull. I consume maybe one energy drink per month now, and have stable iron levels, so I also wonder if those are related.

Has your diet shifted?

I drink a lot of coffee and when I donated blood last, the person testing my iron levels remarked that it was a good thing I was giving blood, as the level was nice and high (they weren't remarking on my health, just on the high iron level). I don't take any supplements or eat a ridiculous amount of red meats and such, but I have a diet that includes some amount of meat, vegetables that are good sources of iron and breakfast cereal that is fortified with iron.

>> A study has shown that caffeine may lead to higher bad cholesterol.

I don't believe that is true. The study in question shows that unfiltered coffee may lead to higher bad cholesterol. It has nothing to do with caffeine. Decaffeinated coffee has the same issue.

Holy shit. No wonder I feel so much better after a steak.

In February, I had an aortic dissection. That's a big deal medical emergency with the kill ratio of a special forces operator.

Symptoms were similar to a heart attack, so it took a while to diagnose (John Ritter died of it, because they were treating him for a heart attack). In the ER they kept asking me if I was on coke, viagra, etc. Then someone brought up coffee.

I remember admitting that I had 6 cups that day, and thinking they'd stop taking me seriously. When they* finally figured out my medical situation and told me I needed to have IMMMEDIATE open heart surgery, the first thing I said was "thank god I'm not a hypochondriac".

Then I worried about my family and work and shit like that. But thanks to coffee my first worry was they'd think I "a bubblegummer".

* - "they" btw, was an awesome nurse and NOT the 3 doctors who saw me there.

I really doubt a nurse made the diagnosis, the legal issues would be a huge problem let alone the education and complexity required to make such a diagnosis. I would know, in 2 years I'll be the single guy on around 1 out of every 10 nights who would have to make that diagnosis and I work in one of the top 10 busiest ED's in the country.

What's up doc.

She absolutely did make the diagnosis. She suspected it based on my pedal pulses, and other things, confirmed it via a CT scan, and got the surgery scheduled. It was like when the Wolf showed up in Pulp Fiction.

Now the truth is she wasn't a random nurse. She is an NP named Nathania Francis and she has some feeding monitoring patent and her own startup in the medical space (this is her bio on her company's staff page: http://www.gnftechnologies.com/gnf-management.php). No way I wasn't googling the person who saved my life.

The surgeon that night, Gustave Pogo, was great too. Turns out everyone in the NY/LI area knows of him.

But the three doctors who walked in, looked at me, and walked out, they didn't save my life. And this includes at least one specialist from the cardio-thoracic unit.

I am/was a fireman with the FDNY (past tense due to this surgery...), so have encountered a lot of emergency medicine in real life. My own medical training is limited (I always joke that "I know enough to watch someone die"), but I can definitely recognize when someone is going through the steps of diagnosing a problem.

      Interesting, didn't sound like an ordinary nurse. Sorry if I came off somewhat arrogant in my earlier post.

      Was she acting as a nurse or NP when she was taking care of you? The radiologist deserves some credit too in my opinion as they are the one to interpret the study. It is easy to include aortic dissection in differential along with other things that could kill you quickly (e.g. MI, pulm embolism, pneumothorax, etc ...) but harder to make the definitive diagnosis. Glad you made it.

>> Sorry if I came off somewhat arrogant in my earlier post.

I only trust arrogant & unapproachable doctors. This parody couldn't be truer: http://www.theonion.com/articles/doctor-has-troubling-amount...

>> Was she acting as a nurse or NP when she was taking care of you?

Don't know which one, I was focused on myself :). And definitely don't know other things you talked about (other than MI).

Well before I was scanned, she said suspected dissection based on pulses and some other monitors. Then the scan confirmed it. My 2 cardiologists (personal and fd ones) both say I'm lucky she was there.

Your bodies reaction to coffee is interesting, the receptors for caffeine apparently expand up to a certain point, once you reach that level additional caffeine does not good for wakefulness but the side affects continue. It's a ceiling you cannot go beyond but people often don't recognize it.

It's strange that the article hints at genetic differences in caffeine metabolism and sensitivity ("Some people will get edgy from a weak cup of tea. For others, a double espresso is required to get them into the shower in the morning.") but doesn't follow through on the implications. For example, my 23andMe results indicate that I'm a "fast caffeine metabolizer", which is associated with a neutral to slightly lower risk of heart attack due to caffeine consumption, whereas slow caffeine metabolizers have a higher risk. In other words, it's clear that the answer to the question "How Much Caffeine Is Too Much?" is "It depends on your genes."

I can see this in myself. I usually have about 48oz of coffee each day. Obviously less on some days and maybe more on others. On days that I don't drink coffee, I can't tell a difference in my alertness or energy. Honestly, I just really really love the taste, and knocking back a cup is a actually a great stress reliever for me.

Edit: Now that I think about it, my dad is the same way. I've watched him multiple times drink a cup or two before bed and have no problems sleeping. On the other hand, my mom can drink a 12oz cup and get a nice boost of energy.

If you're not a coffee person: http://www.caffeineinformer.com/death-by-caffeine

The article doesn't talk about aggression. I'd be interested in seeing some good quality research comparing people's responses to stuff when they're had caffene vs not.

It's frustrating that the evidence around mental health is so poor. I think that small amounts of caffeine destroy my sleep hygiene so I avoid it after midday. But it'd be great to know if a couple of cups of coffee in the morning was probably good or probably not good.

The only one that can really gague that is yourself - have some coffee in the morning, check how you feel and how you sleep at night.

Better would be to separate decaf and fully caffeinated grinds into numbered packages, keep a sleep journal, and then after three weeks see if there were any meaningful difference. Otherwise the results are going to be heavily influenced.

Just to add another data point - I seem to be very sensitive to caffeine, too. Any more than a small cup of coffee in the morning will lower my sleep quality.

Sometime I find myself getting strangely aggressive about things if I have, say, two small cups of coffee. It helps a lot to get me going in the morning, but I have to be very careful, and take frequent vacations. I used to be able to drink a lot of coffee, too much, but I've gotten much more sensitive as I've gotten older.

tl;dr: "While clinicians may observe benefits and risks of caffeine intake, the effects are still being debated in academic circles."

This may be too Talebian a reaction, but isn't the track record of "take this-doesn't-occur-in-significant-quanities-in-food chemical and your health will improve" quite poor? Non-food chemicals are often very useful for acute interventions (e.g. antibiotics, chemotherapy), but at least in modern times, they almost always do more harm than good when taken long-term.

(To avoid getting sidetracked by chronic medicines that some people swear by, I'm directing this point more at non-food drugs that are designed to take people from normal health to great health rather than from a disease state back to normal.)

Googled "Talebian" and came up dry, but yeah. One thing that comes to mind that's used widely to thicken things like non-dairy milks (Soy/Rice/Almond) or anything that needs to be thickened/gelled is carrageenan, a seaweed extract that's been tied in multiple peer-reviewed animal studies to cancer.

Probably referring to Nassim Nicholas Taleb [0], who puts emphasis on the importance of random, rare events.

0. http://en.wikipedia.org/wiki/Nassim_Nicholas_Taleb

Google instead "Nassim Taleb", in particular his ideas surrounding iatrogenics (harm done by the healer), and "via negativa" as a heuristic for fixing systemic problems, i.e., removing things (chemicals/drugs) from a system (human body) to reduce the complexity of interactions and side effects.

Where do you get "your health will improve"? The point of caffeine is not to improve your health. It's to improve your mental functioning. Mental functioning is not something our brains evolved for. In fact our brains are quite profoundly flawed for that task.

Exercise is an amazing alternative.

I'll never cease to be amazed by how much more alert, focused and productive I feel when I take time away to get to the gym instead of grabbing another cup of coffee and keeping at it.

I remember a couple times I went to DefCon there was a guy with a booth selling pure caffeine powder in little baggies.

I didn't start drinking coffee until my mid thirties. I can resoundingly say I slept better and woke up easier without it.

That stuff is more powerful (stimulant effect-wise) by weight than cocaine and thus much easier to O.D. on. I can't imagine being that caffeine-addicted.

Sleep patterns do tend to change with age.

I find that caffeine after ~2 P.M. is a lot more disruptive than before. I drink ~40 fluid ounces of strong drip coffee and don't have any trouble waking up (or any sort of headache, at least not anything immediate, I definitely service the habit). If I stick closer to 30 floz, I don't think I get a headache at all.

in the reddit nootropics forum the other day there was a post from someone who almost accidently OD'd on caffeine.

Alot of the users there use caffeine powder, and he had his bags of powder mixed up with his vitamin c powder and almost drank a drink with multiple grams of caffeine in it. He realized it at the last second and stopped.

moral of the story: caffeine has a fairly low lethal dose and can be dangerous when using the powdered form

Even if it's "multiple grams of caffeine", it's still very far from the 14 kg mentioned in the article... Actually the only way I imagine someone being able to have such an intake would be to use many, many caffeine pills... Way more that the number of sleep pills suicidal people use...

This guy knows: http://www.tmcm.com/tmcm/

400 mg = too much

200 mg = too little

Quoting from Pubmed (via nih.gov):

"The present study compared the effects of caffeine on subjective arousal among introverts and extraverts.... caffeine improved the task performance of extraverts but overaroused introverts and thus impaired their performance."

http://www.ncbi.nlm.nih.gov/pubmed/10472512

The second part of your quote (which comes first) was previous research they were setting out to repeat, instead they conclude with "Results do not support the hypothesis that caffeine differentially affects extraverts and introverts".

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