1708: "Dehydration"

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Re: 1708: "Dehydration"

Postby Spambot5546 » Tue Jul 19, 2016 5:31 pm UTC

Things I was told back when I was in the military, where the cure for every ailment is 800mg tablets of Motrin and more hydration. If you're a physician or dietitian (or nutritionist. I always forget which one is a pseudoscience and can't be arsed to google it) you might know better, but this gets thousands of people through basic training so presumably it's working on at least a basic level.

  • If you're thirsty you're already dehydrated. Don't wait until then.
  • Dark urine is bad. I know this has been debunked in this thread but really if you have the kind of diet that will turn your urine dark regardless of hydration level you probably know it.
  • "One-half to three-quarters canteen per hour, not to exceed 12 canteens per day." Basic training was 13 years ago and I still remember that line. The canteens were 1 quart/approx 1 liter. That advice was specific to people spending all day outside in the Texas sun, of course.
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Re: 1708: "Dehydration"

Postby Eebster the Great » Tue Jul 19, 2016 6:20 pm UTC

ThirdParty wrote:
cellocgw wrote:
harry.lime wrote:
Eebster the Great wrote:
harry.lime wrote:Hydrated = Your urine is clear
Actually, this is by far the most common bit of pop hydration advice you will get from friends and strangers, and it is not based on a single bit of science.
You are evil, and wrong.
[Citation Needed]
Do we really need a citation? Can't we reason it out?

There are two main ways your body uses up water: sweat, for cooling, and urine, for eliminating waste products from your bloodstream. In general, after sweating or urinating you will (at least eventually) need to replace the water you used up. Water can be found in most foods and beverages.

However, the waste products eliminated by urine are, overall, yellow. If your urine is clear, that means your body was not using water to eliminate waste, but was simply eliminating excess water.

It just means it was eliminating relatively little nitrogenous and other pigmented waste compared to water.

So, going by the color of your urine:
dark yellow: you were nearing dehydration even before urinating, so now you definitely need to rehydrate.
pale yellow: you were fine before urinating, but now you probably need to rehydrate.
clear: you were overhydrated before urinating, but now you are probably fine.

What makes you think any of that? Sure, the amount of water eliminated relative to other colored substances will affect color, but how can you possibly determine from that fact what color corresponds to what amount of water or what amount is "correct"? The actual evidence for this claim is not good. For instance, here are some studies indicating urine color charts are not a good way of estimating hydration: [1][2][3]. These studies did find a statistically significant correlation (duh), but that doesn't mean the correlation is very strong or the tool very reliable: [4][5]. The typical conclusion is that within six hours after exercise, the color chart is almost completely useless, whereas after resting it is a useful but imprecise method. This gssiweb article for instance describes the test as an "Easy, rapid, screening tool" but "Easily confounded, timing critical, frequency and color subjective."

But the biggest issue is that nobody can seem to agree on what color is acceptable. Terms like "pale yellow" and "dark yellow" are not useful without a chart, and the studies I linked don't even seem to be using the same chart. Look online for instance and see the difference.

From a practical standpoint, there aren't many times I can see people actually doing this. I can't find any evidence that the strategy of monitoring urine color is more useful than simply telling people to pay attention to their thirst and drink when thirsty. In fact, the studies all indicate that after exercise, color monitoring is completely useless. When you're sitting around at home, it is simply unnecessary. When you are sick, your urine may well be pigmented anyway for a variety of reasons (and odds are you are dehydrated; you probably already know this). One potential real use is in nursing homes, which is why that kept coming up in the articles I researched, but then it's the nurse monitoring it, not the patient.

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Re: 1708: "Dehydration"

Postby Quizatzhaderac » Tue Jul 19, 2016 6:27 pm UTC

eidako wrote:Lethal does chart
I love that the water in the coffee is 4.7 times as dangerous as the caffeine.
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Re: 1708: "Dehydration"

Postby orthogon » Tue Jul 19, 2016 7:04 pm UTC

Eternal Density wrote: OTOH , having a few litres of saline solution dripped into one's veins isn't much fun, and tends to cause sleep loss due to the resultant need for requent trips to the unhydration facility.


I found it really weird that I had to urinate while on a drip. Rationally I can understand why, but I guess intuitively I don't really think of my kidneys taking water and stuff out of my bloodstream and pouring it into my bladder. In my mental model I suspect my bladder is just attached directly to my digestive system like my intestines are, perhaps via some kind of filter. Also i probably thought that the doctors could just feed in the right amount of water to balance the losses, so I should hardly have needed to pee at all. The point mentioned up thread - that urine also carries away other waste products - is presumably the explanation.

Oh, also I was off my tits on opiates, which made everything seen a bit weird.
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Re: 1708: "Dehydration"

Postby Zinho » Tue Jul 19, 2016 7:56 pm UTC

Quizatzhaderac wrote:
ijuin wrote:Just how much water is meant by the unit "glass" being used here?
Eight ounces, but specifically served in a container made out of glass, as opposed to a cup made out of any other material.

I couldn't have said it better myself :mrgreen:
Quizatzhaderac wrote:
SDK wrote:Don't know how big your "glass" is, but even your first rule of thumb is WAY over 8 glasses of water a day.
Zinho's rules were upper limits, as in: You can drink less, but if you're considering drinking more: STOP, something is very wrong.

This.

With BHG suggesting 5/min and Randall's second punchline mentioning 3,000/day I felt it necessary to point out that BHG doesn't mind casually suggesting methods of accidental suicide to people too lazy to do their own research. Randall is also obviously joking, since no one changes oil at 8 miles, either.* Death by over-hydration falls into the category of "we wouldn't have to mention this if it hadn't been a problem in the past". I like this crowd, and given our propensity for making games out of Randall's punchlines I wanted to head off any lethal silliness before it starts.

For people looking for actual water-drinking advice, Spambot5546's 1/2 canteen (~16 fluid ounces, or 2 glasses) of water per hour is appropriate for most people being casually active in the outdoors. Sitting at a desk you'd probably need much less. YMMV, please don't kill yourself by drinking more water than you need.

*off topic: my van's getting close to this; I've skipped the last three oil changes because the engine is burning oil in its old age and I've added 3x the engine's oil capacity since the last "change" operation. Seems to be running fine, and the oil's color and transparency is good; on the other hand, it may be time for me to consider looking for a newer engine...

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Re: 1708: "Dehydration"

Postby Aiwendil » Tue Jul 19, 2016 9:29 pm UTC

RogueCynic wrote:Alcohol and carbonated beverages do not count because they tend to dry out a person.


Alcohol in high enough concentrations can be net dehydrating, sure, but I really doubt that carbonation has any effect. I can't believe that drinking a glass of seltzer is less hydrating than drinking a glass of plain water.

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Re: 1708: "Dehydration"

Postby Neil_Boekend » Tue Jul 19, 2016 10:52 pm UTC

My hand just fell off and crumbled to dust on the floor. Could this be caused by drinking too little?
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Re: 1708: "Dehydration"

Postby ps.02 » Tue Jul 19, 2016 10:55 pm UTC

ThirdParty wrote:There are two main ways your body uses up water: sweat, for cooling, and urine, for eliminating waste products from your bloodstream.

You forgot a third vector which, Uncle Google suggests, is just as significant as sweating. This may not affect the main thrust of your opinions below, but it does affect your credibility.
However, the waste products eliminated by urine are, overall, yellow. If your urine is clear, that means your body was not using water to eliminate waste, but was simply eliminating excess water.

There's where the citation is needed, see? Let's count some assumptions:

- Waste products disposed of in urine are all the same color;
- This color is strong enough that if you don't see it, there must not be any waste;
- The color of urine is only from the waste products, and not some other random process;
- There are only two purposes for urine: eliminating excess water, and eliminating other wastes;
- There's no appreciable delay in the control system between hydration level and urine expulsion (i.e., urine is not collected into some sort of holding area. or "bladder" if you will, for any length of time)

These assumptions may be true or they may be false, but they aren't just things you can "reason out" without evidence or citation.

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Re: 1708: "Dehydration"

Postby da Doctah » Wed Jul 20, 2016 1:55 am UTC

ThirdParty wrote:the waste products eliminated by urine are, overall, yellow. If your urine is clear, that means your body was not using water to eliminate waste, but was simply eliminating excess water.

So, going by the color of your urine:
dark yellow: you were nearing dehydration even before urinating, so now you definitely need to rehydrate.
pale yellow: you were fine before urinating, but now you probably need to rehydrate.
clear: you were overhydrated before urinating, but now you are probably fine.


I'm just going to toss this word out there and see what happens: riboflavin.

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Re: 1708: "Dehydration"

Postby Pfhorrest » Wed Jul 20, 2016 2:35 am UTC

...is a tool of the commie devil seeking to corrupt our precious bodily fluids, along with fluoridated drinking water.

Sorry, was that not the right brand of crazy you were expecting?
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Re: 1708: "Dehydration"

Postby Znirk » Wed Jul 20, 2016 6:35 am UTC

Eebster the Great wrote:The (unqualified) "quart" is a liquid quart, equal to 32 fluid ounces.

Never mind the colour of the urine, that right there is your system of measurement taking the piss. What else is in that series? The soggy gallon and the wet pint?

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Re: 1708: "Dehydration"

Postby ThirdParty » Wed Jul 20, 2016 7:21 am UTC

Evidently, from the tone of the replies, I must have stated my thesis too strongly. I meant to be asserting a rule of thumb, not some sort of ironclad law. (While still gently suggesting that harry.lime's recommendation that we aim for clear urine is overshooting the mark a little.) Urochromoanalysis is never going to be an exact science. Let me try again to state the facts about it that we ought to be able to intuit from common sense and everyday experience:

1. Other things equal, the more heavily diluted your urine is with water, the more similar it will be to water in appearance and scent (and presumably flavor too, but if you're so concerned about proper hydration that you're tasting your own urine, you're probably carrying it too far). Source: the observation that almost everything becomes more water-like when diluted with water.

2. Other things equal, your urine will be more heavily diluted with water if you are overhydrated than if you are not, and less heavily diluted with water if you are dehydrated than if you are not. Source: the observation that our bodies attempt to maintain healthy levels of chemicals by expelling ones that are present in excess and retaining ones which are not.

3. If your urine is indistinguishable from water, one possible explanation is that you're overhydrated. (Of course, another possible explanation is that you're bad at distinguishing different fluids from one another.) Source: follows from 1 and 2.

4. If your urine is much darker than usual, one possible explanation is that you are--or at least, were recently--dehydrated. (Of course, another possible explanation is that someone has slipped a weird chemical into your bloodstream that will color your urine even in relatively-trace quantities.) Source: follows from 1 and 2.

Happier?

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Re: 1708: "Dehydration"

Postby Eebster the Great » Wed Jul 20, 2016 7:39 am UTC

Znirk wrote:
Eebster the Great wrote:The (unqualified) "quart" is a liquid quart, equal to 32 fluid ounces.

Never mind the colour of the urine, that right there is your system of measurement taking the piss. What else is in that series? The soggy gallon and the wet pint?

Heh, well the distinction is pretty sensible at least in my mind. A dry pint is a volume of dry material (e.g. wheat) that weighs a pound, and a liquid pint (usually just called a pint) is a volume of water that weighs a pound. These customary units were eventually standardized in England, then later dropped pretty much everywhere outside the U.S. Even in the U.S. the dry units aren't really used by anybody (though the "bushel" as a nominal unit sort of exists), but liquid units are still used because they still make sense in the context of customary units of weight. In particular, a pint is the volume of a pound of water and a fluid ounce is the volume of an ounce of water. This is much more convenient than cubic inches which do not correspond to neat weights of water. Note that the old metric system did basically the same thing, except they defined the kg based on the L rather than the other way around.

Other adjectives can also modify units, like "nautical mile," "troy ounce," and "long ton," with somewhat (or significantly) more obscure and convoluted logic.

ThirdParty wrote:Evidently, from the tone of the replies, I must have stated my thesis too strongly. I meant to be asserting a rule of thumb, not some sort of ironclad law. (While still gently suggesting that harry.lime's recommendation that we aim for clear urine is overshooting the mark a little.) Urochromoanalysis is never going to be an exact science. Let me try again to state the facts about it that we ought to be able to intuit from common sense and everyday experience:

1. Other things equal, the more heavily diluted your urine is with water, the more similar it will be to water in appearance and scent (and presumably flavor too, but if you're so concerned about proper hydration that you're tasting your own urine, you're probably carrying it too far). Source: the observation that almost everything becomes more water-like when diluted with water.

2. Other things equal, your urine will be more heavily diluted with water if you are overhydrated than if you are not, and less heavily diluted with water if you are dehydrated than if you are not. Source: the observation that our bodies attempt to maintain healthy levels of chemicals by expelling ones that are present in excess and retaining ones which are not.

3. If your urine is indistinguishable from water, one possible explanation is that you're overhydrated. (Of course, another possible explanation is that you're bad at distinguishing different fluids from one another.) Source: follows from 1 and 2.

4. If your urine is much darker than usual, one possible explanation is that you are--or at least, were recently--dehydrated. (Of course, another possible explanation is that someone has slipped a weird chemical into your bloodstream that will color your urine even in relatively-trace quantities.) Source: follows from 1 and 2.

Happier?

I mean, not really. The fact that diluting urine makes it paler is pretty obvious, but the implication that dark urine is usually a sign of dehydration is not obvious at all. It could indicate dehydration, but there are many other possibilities. In particular, it could indicate that you were dehydrated hours ago, that you took a multivitamin, or many other things. The only way to reasonably assess which of these is the most likely is to actually perform research, and the actual research shows that present dehydration is only the most likely explanation when resting. The opposite claim is also wrong. You can be extremely dehydrated with clear urine after exercise, again because you were euhydrated or overhydrated when the urine was formed.

The idea that urine gets clearer when it is wetter is true. The idea that many people can actually apply this truism in any practically useful way does not appear to be true, though there are exceptions.

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Re: 1708: "Dehydration"

Postby wayne » Wed Jul 20, 2016 7:58 am UTC

Other adjectives can also modify units, like "nautical mile," "troy ounce," and "long ton," with somewhat (or significantly) more obscure and convoluted logic.


The logic of a nautical mile is actually much clearer (to me anyway) than the logic of the statute mile. It's exactly one minute of degree of the circumference of the Earth at the equator.
At low latitudes, using the minute ticks on a chart can be a reasonably good approximation of distance in (nautical) miles for short flights. At higher latitudes or for longer flights, no so much. (Pre-flight planning by hand, of course, requires either a measuring tool, or finding coordinates and doing the math.)

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Re: 1708: "Dehydration"

Postby Eternal Density » Wed Jul 20, 2016 9:50 am UTC

I drank a bunch of iodine today, but it was yellowish.
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Re: 1708: "Dehydration"

Postby Soupspoon » Wed Jul 20, 2016 11:46 am UTC

wayne wrote:At low latitudes, using the minute ticks on a chart can be a reasonably good approximation of distance in (nautical) miles for short flights. At higher latitudes or for longer flights, no so much. (Pre-flight planning by hand, of course, requires either a measuring tool, or finding coordinates and doing the math.)
It needs saying that people sailing on ships were familiar with this long before people flying on planes were... familiar with planes. ;)

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Re: 1708: "Dehydration"

Postby Brian-M » Wed Jul 20, 2016 12:42 pm UTC

Zinho wrote:Rules of thumb:
  • 1 qt/hr is more than enough water unless you're performing hard labor in the sun
  • 2 qt/hr is pushing the limits of healthy water ingestion, and if you're working that hard outside you should break it up with 50% rest cycles in the shade
  • 1 gal/hr is enough water to trigger hyponatremia in most healthy adults unless supplemented with salts

So, going by the "rule of thumb" that suggests the least amount of water consumption, you're saying we shouldn't drink more than 96 cups of water a day? Or would that be 72 cups a day (because most people don't drink while they're sleeping)? Either way, I don't think I'll have much of a problem following that rule.

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Re: 1708: "Dehydration"

Postby Brian-M » Wed Jul 20, 2016 12:51 pm UTC

Bloopy wrote:I've also noticed that I'm less likely to get leg/toe cramps if I drink a few beers as opposed to drinking just a little water. Maybe it's because the dehydrating effect of the alcohol comes on later.

Are you sure it's not just an effect of alcohol consumption? Alcohol causes your blood vessels to dilate, which improves circulation, which can help prevent cramps.

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Re: 1708: "Dehydration"

Postby orthogon » Wed Jul 20, 2016 2:21 pm UTC

Another thing: are we judging the color of the urine "in-flight" as it were, or by the color of the fluid the bowl? In the latter case the amount of water diluting the pee is an important nuisance factor, but in the former case it needs to be quite yellow before the color is visible.

(I've been monitoring my own output today, and appear to be horribly dehydrated however much I drink).
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1708: "Dehydration"

Postby Soupspoon » Wed Jul 20, 2016 2:23 pm UTC

orthogon wrote:(I've been monitoring my own output today, and appear to be horribly dehydrated however much I drink).
There may be famous adherents to the practice, but a lot of people would say that you shouldn't be drinking any of your own output. Or anybody else's, come to that.

:P

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Re: 1708: "Dehydration"

Postby x7eggert » Wed Jul 20, 2016 2:28 pm UTC

ps.02 wrote:There's where the citation is needed, see? Let's count some assumptions:

- Waste products disposed of in urine are all the same color;
- This color is strong enough that if you don't see it, there must not be any waste;
- The color of urine is only from the waste products, and not some other random process;
- There are only two purposes for urine: eliminating excess water, and eliminating other wastes;
- There's no appreciable delay in the control system between hydration level and urine expulsion (i.e., urine is not collected into some sort of holding area. or "bladder" if you will, for any length of time)

These assumptions may be true or they may be false, but they aren't just things you can "reason out" without evidence or citation.


1) Any at least remotely healthy diet contains enough protein to color the urine
2) You are alive
3) If you urinate enough to get rid of the yellow stuff, you urinate enough to get rid of everything else.

That's enough for a hypothesis, even though Occam argued: God is almighty, therefore he may use the complicated path.


(PS, polar bears tend to only eat fat because they'd need to pee more when eating protein (muscles), but there isn't much drinkable water.)

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Re: 1708: "Dehydration"

Postby HES » Wed Jul 20, 2016 2:33 pm UTC

orthogon wrote:Another thing: are we judging the color of the urine "in-flight" as it were, or by the color of the fluid the bowl?

What tree has a bowl?
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Re: 1708: "Dehydration"

Postby DavidSh » Wed Jul 20, 2016 5:00 pm UTC

HES wrote:What tree has a bowl?

A lava tree?

Spoiler:
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Re: 1708: "Dehydration"

Postby orthogon » Wed Jul 20, 2016 9:56 pm UTC

Soupspoon wrote:
orthogon wrote:(I've been monitoring my own output today, and appear to be horribly dehydrated however much I drink).
There may be famous adherents to the practice, but a lot of people would say that you shouldn't be drinking any of your own output. Or anybody else's, come to that.

:P

Heh. :-)

Update: I've just gone and eaten asparagus, so the whole experiment is fatally compromised.
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1708: "Dehydration"

Postby Zinho » Thu Jul 21, 2016 9:41 pm UTC

Brian-M wrote:
Zinho wrote:Rules of thumb:
  • 1 qt/hr is more than enough water unless you're performing hard labor in the sun
  • 2 qt/hr is pushing the limits of healthy water ingestion, and if you're working that hard outside you should break it up with 50% rest cycles in the shade
  • 1 gal/hr is enough water to trigger hyponatremia in most healthy adults unless supplemented with salts

So, going by the "rule of thumb" that suggests the least amount of water consumption, you're saying we shouldn't drink more than 96 cups of water a day? Or would that be 72 cups a day (because most people don't drink while they're sleeping)? Either way, I don't think I'll have much of a problem following that rule.

Yes, I'm suggesting an upper limit, although I'd pick 64 cups/day as the high-water mark (so to speak).

As an aside, you really should be getting 8 hrs of sleep [citation needed] 8-)

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Re: 1708: "Dehydration"

Postby ThirdParty » Thu Jul 21, 2016 10:20 pm UTC

Zinho wrote:As an aside, you really should be getting 8 hrs of sleep [citation needed] 8-)
Ooh, let's talk about sleep!

I've heard all of the following pieces of advice:
  • You should get an average of 8 hours of sleep per night. (Sleeping too much is associated with depression; sleeping too little interferes with intelligence.)
  • You should go to sleep at the same time each night, and wake up at the same time each morning. (As opposed to, say, sleeping in on weekends; having a variable sleep schedule can lead to insomnia.)
  • Each individual sleep period should be a multiple of 90 minutes. (Because this is the length of a sleep cycle; interrupting one can cause grogginess.)

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Re: 1708: "Dehydration"

Postby wayne » Sat Jul 23, 2016 10:57 am UTC

Soupspoon wrote:
wayne wrote:At low latitudes, using the minute ticks on a chart can be a reasonably good approximation of distance in (nautical) miles for short flights. At higher latitudes or for longer flights, no so much. (Pre-flight planning by hand, of course, requires either a measuring tool, or finding coordinates and doing the math.)
It needs saying that people sailing on ships were familiar with this long before people flying on planes were... familiar with planes. ;)


Hence the term "nautical mile," rather than "Aerial mile" or some such. :wink:

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Re: 1708: "Dehydration"

Postby da Doctah » Sat Jul 23, 2016 3:46 pm UTC

ThirdParty wrote:
  • You should get an average of 8 hours of sleep per night. (Sleeping too much is associated with depression; sleeping too little interferes with intelligence.)
  • You should go to sleep at the same time each night, and wake up at the same time each morning. (As opposed to, say, sleeping in on weekends; having a variable sleep schedule can lead to insomnia.)
  • Each individual sleep period should be a multiple of 90 minutes. (Because this is the length of a sleep cycle; interrupting one can cause grogginess.)


And then you realize that 8 hours is not a multiple of 90 minutes, and the whole thing falls apart.

(That's not even factoring in the "power nap", which nobody suggests should last 90 minutes.)

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Re: 1708: "Dehydration"

Postby pogrmman » Sat Jul 23, 2016 6:17 pm UTC

Zinho wrote:Yes, I'm suggesting an upper limit, although I'd pick 64 cups/day as the high-water mark (so to speak).


64 cups a day seems excessive unless you are in the desert or working hard -- that's 15 L per day! I think 10 L a day is a more reasonable upper limit -- or 42 cups. For a lower limit, I'd probably put around 1.5 to 2 L -- or 6 to 8 cups if you are doing any kind of work at all outside.

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Re: 1708: "Dehydration"

Postby Copper Bezel » Sun Jul 24, 2016 8:12 am UTC

da Doctah wrote:
ThirdParty wrote:
  • You should get an average of 8 hours of sleep per night. (Sleeping too much is associated with depression; sleeping too little interferes with intelligence.)
  • You should go to sleep at the same time each night, and wake up at the same time each morning. (As opposed to, say, sleeping in on weekends; having a variable sleep schedule can lead to insomnia.)
  • Each individual sleep period should be a multiple of 90 minutes. (Because this is the length of a sleep cycle; interrupting one can cause grogginess.)


And then you realize that 8 hours is not a multiple of 90 minutes, and the whole thing falls apart.

(That's not even factoring in the "power nap", which nobody suggests should last 90 minutes.)

Hmm, but it doesn't say how long the "average" has to be taken over vs. how long a schedule has to be maintained to be "the same" and not "variable". Maybe you could do two-month-long blocks of 7.5 hours a night followed by a month of 9?
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Re: 1708: "Dehydration"

Postby da Doctah » Sun Jul 24, 2016 11:34 am UTC

Copper Bezel wrote:Hmm, but it doesn't say how long the "average" has to be taken over vs. how long a schedule has to be maintained to be "the same" and not "variable". Maybe you could do two-month-long blocks of 7.5 hours a night followed by a month of 9?

But that violates the second rule that says you go to bed at the same time each night and get up at the same time each morning.

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Re: 1708: "Dehydration"

Postby ThirdParty » Sun Jul 24, 2016 2:00 pm UTC

Copper Bezel wrote:
da Doctah wrote:
ThirdParty wrote:I've heard all of the following pieces of advice:
  • You should get an average of 8 hours of sleep per night. (Sleeping too much is associated with depression; sleeping too little interferes with intelligence.)
  • You should go to sleep at the same time each night, and wake up at the same time each morning. (As opposed to, say, sleeping in on weekends; having a variable sleep schedule can lead to insomnia.)
  • Each individual sleep period should be a multiple of 90 minutes. (Because this is the length of a sleep cycle; interrupting one can cause grogginess.)
And then you realize that 8 hours is not a multiple of 90 minutes, and the whole thing falls apart.

(That's not even factoring in the "power nap", which nobody suggests should last 90 minutes.)
Hmm, but it doesn't say how long the "average" has to be taken over vs. how long a schedule has to be maintained to be "the same" and not "variable". Maybe you could do two-month-long blocks of 7.5 hours a night followed by a month of 9?
Just to clarify, in case it wasn't obvious: I intended the three to be contradictory. Believing thirdhand medical advice, especially without at least eyeballing it to see whether it's plausible, is a bad idea.

(Although it is true that I've heard each of them, and it isn't totally implausible to criticize the average American's sleep for being too brief, too variable, and too likely to be interrupted by an alarm clock.)

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Re: 1708: "Dehydration"

Postby somitomi » Sun Jul 24, 2016 2:57 pm UTC

Neil_Boekend wrote:My hand just fell off and crumbled to dust on the floor. Could this be caused by drinking too little?

Maybe it's some fungus, the same thing happened to our cherry tree.
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Re: 1708: "Dehydration"

Postby Copper Bezel » Sun Jul 24, 2016 9:22 pm UTC

ThirdParty wrote:Just to clarify, in case it wasn't obvious: I intended the three to be contradictory.

Yeah, I was just playing along with the gag.

da Doctah wrote:
Copper Bezel wrote:Hmm, but it doesn't say how long the "average" has to be taken over vs. how long a schedule has to be maintained to be "the same" and not "variable". Maybe you could do two-month-long blocks of 7.5 hours a night followed by a month of 9?

But that violates the second rule that says you go to bed at the same time each night and get up at the same time each morning.

Well, I'd thought a month would be long enough to count as stable, but I suppose that in reality, it's never the same time twice, anyway, and you'd only get to sleep once.

Oh geez, do you think it has to be the same time as other people, too?
Last edited by Copper Bezel on Mon Jul 25, 2016 6:57 am UTC, edited 1 time in total.
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Re: 1708: "Dehydration"

Postby Soupspoon » Mon Jul 25, 2016 5:07 am UTC

somitomi wrote:
Neil_Boekend wrote:My hand just fell off and crumbled to dust on the floor. Could this be caused by drinking too little?
Maybe it's some fungus, the same thing happened to our cherry tree.
If your cherry tree had a hand in the first place, you may have been dabbling a little too much into GM technology...

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Re: 1708: "Dehydration"

Postby orthogon » Mon Jul 25, 2016 8:17 am UTC

da Doctah wrote:
ThirdParty wrote:
    [...]
  • Each individual sleep period should be a multiple of 90 minutes. (Because this is the length of a sleep cycle; interrupting one can cause grogginess.)

And then you realize that 8 hours is not a multiple of 90 minutes, and the whole thing falls apart.

That a sleep cycle is about 90 minutes appears to be fairly uncontroversial, but multiplying this up to arrive at the correct duration for a whole night's sleep seems suspect. Presumably there's some variation amongst individuals, and a 6% change in the 90 minutes would turn the nominal 7.5 hours into anything from 7 to 8 hours. Added to that, the hypnogram on the comprehensive Wikipedia page on sleep suggests variation in the length and structure of sleep cycles even during one sleep episode in one individual. So whilst I think we can conclude that 45 minutes is probably a pessimal length of sleep for most people, without taking an EEG it's hard to draw any conclusions for exactly how long we should sleep at night.

The whole topic is absolutely fascinating, anyway.
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1708: "Dehydration"

Postby Soupspoon » Mon Jul 25, 2016 12:14 pm UTC

orthogon wrote:The whole topic is absolutely fascinating, anyway.
It's been a wake-up call, certainly.

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Re: 1708: "Dehydration"

Postby somitomi » Mon Jul 25, 2016 1:59 pm UTC

Soupspoon wrote:
somitomi wrote:
Neil_Boekend wrote:My hand just fell off and crumbled to dust on the floor. Could this be caused by drinking too little?
Maybe it's some fungus, the same thing happened to our cherry tree.
If your cherry tree had a hand in the first place, you may have been dabbling a little too much into GM technology...

There was some confusion, but we decided it still counts as a tree limb, so close enough.
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Re: 1708: "Dehydration"

Postby solune » Mon Jul 25, 2016 3:08 pm UTC

Eebster the Great wrote:The idea that urine gets clearer when it is wetter is true. The idea that many people can actually apply this truism in any practically useful way does not appear to be true, though there are exceptions.


Let me see if I understand the respective positions:

Thirparty is stating that "If your urine is dark yellow you should drink a glass of water" is a good rule of thumb.
-> it is good enough that if everyone used it, the average person would get healthier.

Eebster the Great is stating that: If your urine is dark yellow, there's a good probability that something other than dehydration is causing it.

Could you quantify your position ? Is it 70% of people who should not use the rule of thumb at all ? more ? less ?

More precisely here's the problem for which I want to do a Bayesian analysis:
1) I've observed my average pee to be light yellow (a term known only to me, but so is my observation)
2) I do not take food supplements of any kind and do not have any known medical condition
3) I observe my latest pee to be dark yellow
->What is the probability that my water need is less than a large glass of water ?

Copper Bezel wrote:
da Doctah wrote:But that violates the second rule that says you go to bed at the same time each night and get up at the same time each morning.

Oh geez, do you think it has to be the same time as other people, too?

A study has found that Nepalese people sleep very well, so you should try going to sleep at the same time as them. :mrgreen:

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Re: 1708: "Dehydration"

Postby gmalivuk » Mon Jul 25, 2016 3:23 pm UTC

orthogon wrote:That a sleep cycle is about 90 minutes appears to be fairly uncontroversial, but multiplying this up to arrive at the correct duration for a whole night's sleep seems suspect.
I'd imagine that sleep cycle length is only particularly helpful information when you're deciding how long a nap should be.

For whole-night sleep time, the National Sleep Foundation's recommendations appear to be based on the most robust data we have available, and if you shoot for their recommended total sleep time, you'll probably have good long-term (sleep-related) health even if you occasionally wake up in the middle of a sleep cycle and feel groggy for a few hours on that particular day.
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