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Comment by oedmarap | Hacker News Reader

One of the strategies that changed my sleep quality for the better is to stop taking coffee after 9 AM; after learning that caffeine has a half-life of around 6-7 hours[0], but a quarter-life of around 12 hours. If you have a cup of coffee at noon, a quarter of that caffeine can still be circulating around your brain at midnight.

[0] https://youtu.be/k5BMGmf1ai0

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This link unfortunately doesnt really address the chemical imbalances which are normalised throughout society as stress and aging. If you consider yourself to be just a complex chemical reaction with a consciousness as the end result of the complex chemical reactions which have evolved over thousands of years, then I'd simply be looking at chemical solutions for good rest.

Its not strictly true that caffeine has a half life of 6-7 hours, nicotine reduces this to 3-4hrs and some prescription drugs also affect the half life either by shortening it or increasing it, in extreme to 24-48hrs.

I found a few grams of Taurine will improve and increase sleep, the science is out there, the more you take the more you sleep and you can sleep through fire alarms and all sorts so use with caution.

Now a restless mind can also keep people awake, so increasing 5-alpha reductase by consuming Glycine can then break down cortisol. You will laugh your head off with lots of Glycine, so dont blame me if you laugh your head off in a stressful situation and get fired from a job or something!

https://en.wikipedia.org/wiki/5%CE%B1-Reductase#List_of_conv...

What 5-alpha reductase would you suggest for someone wanting to test this out?

I'd suggest Glycine but if you are not allowed sugar for medical reasons, consult a doctor first. Glycine like many chemicals play many parts in the body and combine with other chemicals, like other amino acids. Its one of the ingredients of creatine, now creatine gets broken down into creatinine which is a gram positive and gram negative anti bacterial, and bacteria in the brain & body can also affect personality so there may be other factors at play contributing to your mood. If you want to study this, then you should know the answer to your question!

Pedantic HN style comment: doesn't half-life of 6 hours always imply "quarter-life" of 12 hours? :)

(though I wouldn't have realized that without your comment, so thanks for that)

Depends on if it’s linear or a curve, right?

Are there any examples of this? If its half-life is 6 hours, then after six hours half of the caffeine is still there, and we know caffeine has a half life of 6 hours. I don't know of any molecules with a non-linear half-life but I might be completely wrong

There's a whole area for this - pharmacokinetics. See e.g. https://en.wikipedia.org/wiki/Biological_half-life#Rate_equa... for examples of e.g. first order models (exponential elimination rate, etc.) It has to do with protein binding dynamics among other factors I have no idea about. Remember that you are dealing with biological systems.

Some of these processes to do with elimination and clearance are very much non-linear and are modelled with diff equations. https://en.wikipedia.org/wiki/Physiologically_based_pharmaco...

There aren't many with zero-order pharmacokinetics (linear curve decay). The only notable exception is alcohol though.

Interesting, for a second I thought that had to be wrong because I was aware of aspirin and alcohol, but apparently they are the two common ones and the vast majority are a bit more complex, which also makes sense if you think about it logically I suppose.

It looks like in addition to those, others with zero-order pharmacokinetics include salicylates (salts of salicylic acid incl. aspirin), omeprazole (for indigestion), fluoxetine (antidepressant), phenytoin (for epilepsy), methanol (a poisonous alcohol) and cisplatin (chemo medication.)

A constant half-life is necessarily an exponential decrease (linear curve on a logarithmic plot). So, yes, if the half-life is 6 hours without qualification, then the quarter life will be 12 hours.

Though, in real-life you get things like enzyme saturation, depletion of chemicals consumed in the metabolism of the chemical, etc. Real world pharmacokinetics are probably not exactly constant half-lives.

For example, IIRC, the average American adult male saturates his alcohol dehydrogenase at about 3/4 shot of 80 proof liquor per hour. Below saturation, I presume ethanol has something close to a constant (and short) half-life, but that exponential decrease is only observed at alcohol concentrations where the effects of alcohol aren't very obvious. So, for most practical purposes, the biological half-life of ethanol doesn't apply and its metabolism is better approximated as a constant rate process.

Even if it was as simple as any physical system, it is still something one might not realize for never making the correct question.

Technically those two phrases mean the same, but people will draw very different conclusions from them.

It serves as emphasis. Most people have interpreted "caffeine has a half-life of X hours" to mean "oh so it's fine to have it just X hours before bed.

By explicitly calling out the quarter-life, it prompts people to think if a quarter of the amount would still affect them.

This is one of those things you just have to try and see if it works. I've quit caffeine completely for a few weeks, and didn't notice a difference in my sleep quality.

Me too - but I stopped for 30 days and didn't cut other caffeine sources..

Actually for me I sleep better at night with caffeine in the morning. I find it helps with having a proper active / rest cycle, i.e. concentrate energy and stress during the first part of the day so I can start to wind down in the afternoon, instead of hovering around mildly stressed all the day and the evening.

I found it didn’t improve my sleep quality or my ability to fall asleep. However - I do feel like I have a slightly easier time getting out of bed now.

I’ve been off caffeine for a year or more. Having it actually makes my stomach slightly upset now. Similar to sugary drinks - I can’t do them anymore. Once I gave them up - I couldn’t go back.

I'm not certain how relevant that is. I definitely don't feel more awake 6 hours after coffee let alone 12 so clearly not all effects are still there. Claims like these are quoting numbers while implying things which aren't true a priori.

Sleep is admittedly easily disrupted but I also haven't noticed a difference in sleep quality when skipping my afternoon cup.

Different people reacts differently. I normally drinks 2-3 cups a day, last one sometimes after 8 PM. So to test some claims about coffee being so bad etc, I completely removed coffee from my life for a month - zero difference. And the same is true for Yerba Mate for me (although with Yerba I definitely feel different for few hours). But I believe that some simply react more to this substance.

This. One cup a day here at 07:30 and that’s it. Was actually life changing.

My non-sleep nights suddenly make sense, thanks!

I only have decaff, rarely though, and only before 9AM as well. Otherwise I have green tea, and not after 1pm.

I wonder why for coffee you have it decaff but you are happy with tea, that has more caffeine than coffee.

Tea of any kind doesn't have more caffeine than Coffee. And green tea has less caffeine than black tea.

https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-h...

It was about decaf

I hear that often enough. I think the confusion is that it's true by dry weight of beans/leaves, but a cup of coffee will typically have more caffeine than a cup of tea by a factor of a few.

And how is your sleep?

I switched over to mushroom coffee since I couldn’t tolerate decaf. Still has some caffeine but doesn’t leave me jittery.

I have a very similar approach, but I usually drink a 2nd cup of green tea in the morning. I feel it helps my intermittent fasting.

Thanks. Being a HSP(highly sensitive person) I am always careful of my coffee after lunch. Now I realised I need to either have it early morning or not at all.

I've done the same thing, started remembering a lot more dreams, not sure if that's an indicator of better sleep though.

I’ll often have an espresso in the evening after dinner, and I sleep well after.

Why talk about half-life and quarter-life here instead of full-life (which I guess is around 18-24 hours)? Having less than a quarter of caffein in your system does not impact your sleep?

It's an exponential decay, so full-life is not really a coherent concept. Detectable (but unnoticeable) levels will persist for quite some time and undetectable levels will persist for a bit after that.

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