This Reddit AMA is now finished, thanks for your interest. For further information on what we do, please visit: http://www2.port.ac.uk/department-of-sport-and-exercise-science/staff/prof-mike-tipton.html For more information on the RNLI Respect the Water campaign please visit: https://rnli.org/safety/respect-the-water I'm Mike Tipton, Professor of Human & Applied Physiology at the Extreme Environments Laboratory, DSES, University of Portsmouth, and Editor-in-Chief of Experimental Physiology (The Physiological Society). I’ve led many published studies into the effects of cold water on the body and how best to increase your survival chances. Our team did the research that formed the basis of the RNLI’s Respect the Water campaign which promotes floating as a survival skill if you unexpectedly fall into cold water. AMA until 3pm on the 22/8/18! https://www.youtube.com/watch?v=jIEw55a6dcw https://www.youtube.com/watch?v=jncVb2onYC4 https://www.youtube.com/watch?v=0gd6QC2Emrc

Proof: http://www2.port.ac.uk/department-of-sport-and-exercise-science/staff/prof-mike-tipton.html

Comments: 1223 • Responses: 47  • Date: 

Ceraphh1475 karma

Do you think both Jack and Rose could have survived in the water on the door together?

Mike_Tipton1737 karma

You are better off out of the water than in it. Water removes heat from the body much quicker than air and humans cool about 5 times faster in water compared to air at the same temperature. PS. Rose held her breath for 35 seconds in the film (Titanic) under ice cold water - I doubt this is possible.

IamTheMuffinStuffer381 karma

Do you say this because of shock? What about the swimmers that travel x distance under ice for world records?

Mike_Tipton554 karma

They are cold habituated - see other answers.

LadyHelvetica75 karma

Really? What about mammalian diving reflex? I thought humans were supposed to be able to hold their breath longer in cold water than in hot.

Mike_Tipton275 karma

The diving response (breath hold, reduced heart rate, and selective changes in blood flow) is weak in most adults (stronger in children) and takes time to appear. The cold shock response tends to prevail. Activating both responses at the same time can cause heart irregularities.

RopeyChris596 karma

Hi Mike,

I wonder if you could give me an estimate as to how long someone could survive in the North sea until rescue? I did an offshore survival course for oil rigs not too long ago and the instructors always dodged the question! Also, is it true smokers tend to last longer in open water as their blood vessels are narrower? Cheers!

Mike_Tipton664 karma

Standard 50% survival times are 1h @ 5°C, 2 @ 10°C and 6 @ 15 °C. Enormous variation between individuals depending on external (e.g. sea state) and internal factors (fitness, fatness, nutrition etc). Also these curves tend to ignore those that die in the first minutes from cold shock (up to 60% of deaths in cold water). This makes estimating survival time as much "art" as "science" and SAR times are lengthened considerably to account for this variation. The large number of death from cold shock is the reason the RNLI Respect the Water campaign focuses on this period of immersion and encourages "float to live" and "fight your instincts". https://www.respectthewater.com/?utm_source=ppc&utm_medium=search&utm_campaign=rtw_2018&gclid=EAIaIQobChMI7oW7zrL-3AIVzpPtCh12oAsTEAAYASAAEgK_H_D_BwE

Riccardo91195 karma

Fat people or fit people have a higher chance to survive in cold water?

Mike_Tipton404 karma

Fat has the same thermal characteristics as cork. But when at rest unperfused muscle provides more insulation to the body than fat because there is more of it. This "variable" insulation disappears when you exercise as blood flows into the muscles reducing the insulation they provide. This leaves the "fixed" insulation of fat. People can shiver at about 40% of the aerobic capacity so fit is good for that, and fitter people have a small cold shock response so fit is good for that. No simple answer -be fit for other reason and stay still in the water. Fit and fat very good for cold water!

raddlesnake501 karma

Maritime SAR Coordinator here - We've heard of times where people are about to get rescued and they sort of...shut down. It's almost as if their adrenaline was keeping them going, then as they see the rescue coming, their brain says, "We're all set, I don't need to push any more adrenaline through" and people go under. They get so overwhelmed by the fact that the rescue has arrived that their body preemptively starts to relax.

Do you have any science/data to provide more context to this phenomenon?

Mike_Tipton492 karma

I have heard about this a lot in different rescue scenarios, we call it "Pre-rescue collapse" was first reported back in the 1940s. It may be a form of Autonomic Conflict (see other answers) wave (vagal) of relief and withdrawal of sympathetic drive. Hard to study. Best to keep encouraging people to fight for their survival throught the rescue process.

Nickleons90 karma

I think the OP might also be interested in something I vaguely remember studying back at university. Where victims in long water exposure are relying on the water pressure in lower limbs to maintain blood pressure so removing them from the water in the vertical states creates hypotension and collapse.

I'm sure Mike Tipton can phrase it better however

(Studied at Portsmouth university many years ago and was also a RNLI lifeguard for several years as well so have met you a few times :) )

Mike_Tipton101 karma

Nice to be in contact again. You are talking about collapse during rescue rather than before it. This "rescue collapse" is indeed due to a collapse in arterial pressure as you lift a hypothermic, hypovolaemic casualty vertically from the water and re-expose to the full influence of gravity. Best to lift horizontally if lifting over a long distance.

Shashi2005462 karma

Maybe you can help dispel a local myth. I've lived around my local northern UK canal all my life. Lived on board a narrowboat for years.

It is a locally held belief that if you fall into icy water, one should take a mouthful of that cold canal water as it will help to prevent shock.

This sounds like a load of bollocks to me! But the folk that perpetrate this myth are an old canal family & some are taken in by it.

Can you briefly debunk this please?

Well done with the work for the RNLI. I always donate and I have bequeathed money to them in my will.

Mike_Tipton636 karma

I have not heard of that as a way of reducing cold shock. I would recommend keeping your airway as clear of the water as possible when you have no control of your breathing. Thank you for supporting the RNLI.

bishopwatts422 karma

Can your pee really freeze in your urethra in cold enough waters?

Mike_Tipton513 karma

No

sock2014298 karma

Have you read the original Nazi hypothermia experiments data? What do you think about the ethics of using it? http://articles.latimes.com/1988-10-30/news/mn-958_1_nazi-data-issue

Mike_Tipton514 karma

I have read the Alexander report on the research at Dachau, I have visited Dachau twice with colleagues. We did a Timewatch TV programme on this subject several years ago (no longer available). When asked, survivors of the concentration camps were happy to have the data used for the benefit of mankind. This has tended to be done but without referencing the researchers. https://www.ushmm.org/wlc/en/article.php?ModuleId=10005168

Koy-Boy258 karma

Mr Tipton, let’s say someone expects to be submersed into cold water (ie: sinking ship) and they have a few minutes to prep before contact. Do you think performing the Wim Hof Method in advance would help one brace for the cold and increase one’s survival rate in that situation ?

Mike_Tipton317 karma

Staying calm should certainly help. Prior ventilatory manoeuvres do not reduce the cold shock response in most people. Depending on circumstance I suspect you might want to spend the time getting to the best place you can.

SordidCanary257 karma

This question is super basic, but on the off chance you answer it - often I go on very long runs outside in the Texas heat. Then when I get home I will shower, often in quite cold water to cool off and start the recovery process. Often when I step into the water my breath is essentially taken completely away and I can literally feel myself struggle to draw breaths. What is occurring when this happens? I assume it happens when you jump into freezing water.

Given how important breathing is in water, I wonder if you could let me know why this happens, and if one can mitigate this for a potentially serious situation.

Mike_Tipton338 karma

You are experiencing what we have called "cold shock", driven by a sudden fall in skin temperature. It makes you gasp and breathe at the top of your lung - giving a sensation of breathlessness.
You are better off showing in tepid water to make sure you don't shut down your skin blood flow and your body keeps delivering heat to the skin in the circulation. https://www.youtube.com/watch?v=DzdR0jMgjEI

Jonelololol119 karma

Did you do the ALS ice bucket challenge?

jason_s2000116 karma

GAME OF THRONES SEASON 7 SPOILERS AHEAD

In Game of Thrones 7x06 Jon Snow is knocked into an frozen lake north of the wall. He later emerges and survives. This is seen at the beginning of this video here. I’m just wondering if there’s any possible way that a human could survive this. Me and many other viewers found this kind of ridiculous. It’d be awesome to have an expert comment on it

Edited just for the spoiler warning at the top

Mike_Tipton121 karma

There are ice water swimming races - you need to be habituated to cold to do them. You can survive ice cold water immersion - major risks are cold shock and physical incapacitation. Will not become hypothermic in less than 30 mins if an "average" adult.

RubbrDinghyRapidsBro13 karma

Anecdotal, but people do nude or nearly-nude 'polar bear' dives all the time. Depends how long he was under the water for, and how those furs helped or hindered the shock. Cold shock, Google tells me, is barely worse at 35F than at 55F, which is probably why people can do those polar bear dips and survive.

Edit 2: BIG SPOILER!

Edit: also, magic. GoT world has lots of it, and John Snow has come back from the dead before.

Mike_Tipton17 karma

Yes the cold shock response peaks somewhere between 15 and 10 °C when just wearing swimming trunks. After that the water feel colder then painfully cold (pain receptors activated) but the cold shock response doesn't get much worse - may go on a bit longer. Tipton, M. J., Stubbs, D. A. & Elliott, D. H. (1991) Human initial responses to immersion in cold water at 3 temperatures and following hyperventilation. Journal of Applied Physiology 70(1): 317-322.

CalmEnthusiasm111 karma

Wim Hof... charlatan or is there something to his method?

Personally, I love ice cold water. Haven't been in warm/hot water in almost two years.

Mike_Tipton138 karma

You can certainly habituated to the cold shock response. As few as 5 three minute immersions can halve the response. The response is not really seen in open, cold water swimmers.

mehuiz37 karma

Can you please provide more details regarding being "cold habituated".

Mike_Tipton95 karma

Repeated immersions in cold water result in a reduction in the cold shock response due to alteration in the neural pathway somewhere more central than the peripheral cold receptors. The cold shock response can be halved in a few as 5 x 3 minute immersions. Tipton, M. J., Franks, C. M. & Golden, F. St. C. (1998) Habituation of the initial responses to cold water immersion in humans: a central or peripheral mechanism? Journal of Physiology 512(2): 621-628. Golden, F. St.C. & Tipton, M. J. (1988) Human adaptation to repeated cold immersions. Journal of Physiology 396: 349-363.

the_lord_nikon35 karma

How often would you need to do this to have a practical effect? I used to swim in cold water as a kid, would that still reduce the response now that I am much older?

Mike_Tipton90 karma

We have only tested out to 14 months - half of the habituation lost in that time. Tipton, M. J., Mekjavic, I. B. & Eglin, C. M. (2000) Permanence of the habituation of the initial responses to cold-water immersion. European Journal of Applied Physiology 83:17-21.

Wizzigle93 karma

What advice would you ya e for cold water surfers? Often the waves are much better in the winter in my part of the world but we can only spend a limited amount of time in the water before getting too cold. Thicker wetsuits let us surf longer, but they are uncomfortable and restrict mobility. If you had any advice for staying warm but in thinner wetsuits that would be appreciated!

Mike_Tipton84 karma

The only other option is get fatter i.e. use the physiologists overcoat. Exercising hard in a wet suit might help a bit but probably end up with you getting exhausted. Sorry.

rikki-tikki-deadly17 karma

An addendum to this question, is peeing in the suit going to help, hurt, or ultimately have no effect on how warm you stay?

Mike_Tipton55 karma

Dry suit, with dry underlothing- bad. Wetsuit - no great difference. The urge to urinate on cold water immersion is due to cold shutting down the skin blood flow (vasoconstriction) and hydrostatic squeeze from the water = "cold induced diuresis". https://www.sciencedirect.com/topics/medicine-and-dentistry/cold-induced-diuresis

Trappist173 karma

Would an obese human live longer or shorter in near-freezing water compared to an average human all else being equal?

Mike_Tipton154 karma

Assuming they didn't die from cold shock (same for fat and thin people all other things equal), longer, in water, but probably shorter in air!

spookyblck71 karma

what are the chances of survival in cold water for someone who can’t swim?

Mike_Tipton116 karma

Reasonable if you respect the water, try not to panic and wear a life jacket when indicated.

FacSolumId61 karma

How do you survive in cold water?

Mike_Tipton105 karma

Big question! In short, wear the correct PPE (clothing, lifejacket), if you fall in "float to live" until your breathing is under control https://www.respectthewater.com/?utm_source=ppc&utm_medium=search&utm_campaign=rtw_2018&gclid=EAIaIQobChMI_7O6-rz-3AIVhLDtCh1XIQRKEAAYASAAEgJrHvD_BwE Then do what you need to with your hands before they become incapacitated due to neuromuscular cooling (20 min). They stay still, stay positive and await rescue. Read the Essentials of Sea Survival!

SenorBeef54 karma

When we were kids, maybe 10-15 years old, my friends and I used to go swimming in Lake Erie for hours starting in late April, where the water temp is around 50 degrees. I later looked at a hypothermia chart that indicates that it's quite dangerous - you're potentially looking at "exhaustion or onconciousness" in the 30m-2 hour range. But we'd go swimming for at least 3-4 hours and it wasn't a big deal to us. I'm quite confident we spent several hours continuously in 50 degree water.

Conventional wisdom seems to think that's a fatal mistake, but it never bothered us. Was it because we were very active kids with lots of energy, swimming and jumping and diving into waves, some other reason, or must I be misremembering because we should've been dead?

Mike_Tipton54 karma

Children can also habituate to cold and, if distracted by play, often are less upset by it. Bird, F., House, J. R. & Tipton, M. J. (2015) Adaptation of the cold shock response and cooling rates on swimming following repeated cold water immersions in a group of children aged 10-12 years. International Journal of Aquatic Research and Education, 9: 149-161.

Bird, F., House, J. R. & Tipton, M. J. (2015) The physiological response to immersion in cold water and cooling rates during swimming in a group of children aged 10-11 years. International Journal of Aquatic Research and Education, 9: 162-174.

maz-o50 karma

Are there health benefits to taking ice cold showers?

Mike_Tipton77 karma

Topical question - we are looking at this currently! There have been many claims for cold exposure improving immune function, inflammatory responses etc. The problem is that good quality control data are often missing. We have just reported a positive benefit of open water swimming on depression and have written a review on the topic.
Van Tulleken, C., Tipton, M., Massey, H. & Harper, M. (2018) Open water swimming as a treatment for major depressive disorder. British Medical Journal Case Studies. Tipton, M. J., Collier, N., Massey, H., Corbett, J. & Harper, M. (2017) Cold water immersion: kill or cure? Experimental Physiology.

lego_batman37 karma

Have you ever used any of the techniques you've studied to save yourself from drowning?

Mike_Tipton72 karma

I have cold habituated for triathlons, I have also floated when tired in the sea.

Hayescr37 karma

What are your thoughts on Wim Hoff and his methods for using cold water to improve your health and mental well being?

Mike_Tipton19 karma

I haven't tried it.

Thexorretor31 karma

I do SAR in area with a popular rafting destination -- cold snow runoff water. It's reasonably common to see cardiac events (i.e. heart attacks) from people who fall into the river, usually in in older people. The rafting customers wear wet suits, but that always seemed skimpy to me. I wear a dry suit in these conditions. Is it reasonable and responsible for rafting companies to outfit their clients in wetsuits instead of dry suits?

Mike_Tipton40 karma

A properly fitted and maintained dry suit with a decent amount of underclothing is excellent, a good (tight) fitting wetsuit is almost as good. The problems come when the dry suit gets damaged (seals) and the wetsuit doesn't fit (water flushed underneath). I guess most groups go for wetsuits because they are more robust and less likely to get damaged. Ultimately the answer for this specific case will be in the data of cold-related injuries arising for water entry? Tipton, M. J., Stubbs, D. A. & Elliott, D. H. (1990) The effect of clothing on the initial responses to cold water immersion in man. Journal of the Royal Naval Medical Service 76(2): 89-95. Tipton, M. J. & Vincent, M. J. (1989) Protection provided against the initial responses to cold immersion by a partial coverage wet suit. Aviation Space & Environmental Medicine 60(8): 769-773.

Tipton, M. J. & Balmi, P. J. (1996) The effect of water leakage on the protection provided by immersion protective clothing worn by man. European Journal of Applied Physiology 72: 394-400.

Work from John Hayward (Canada) cooling rates (°C/h) for thin (9.1% body fat) males in 11.8 °C water in: Standard clothing = 2.3 Uninsulated dry suit over light clothing = 1.07 Wetsuit closed cell foam 4.8mm = 0.54 Dry suit made of closed cell foam insulation 4.8mm = 0.31

butkaf31 karma

Have you done any studies on cold water exposure and its effects on mitochondria production, functionality and density?

MechanicalTurkish71 karma

The mitochondria is the powerhouse of the cell.

Mike_Tipton51 karma

Like all other reactions those in the mitochondria are reduced by cooling. The Q10 temperature coefficient is a measure of the rate of change of a biological or chemical system as a consequence of increasing/decreasing the temperature by 10 °C. For example, metabolic and rhythmic processes are particularly depressed by hypothermia (Q10 of about 3); contractile processes have a Q10 of about 2. As hypothermia progresses metabolic and rhythmic processes are depressed 2-3 times more than the rates of diffusion of different metabolites. As I say we haven't done any work on this the closest we come is the impact on performance: Vincent, M. J. & Tipton, M. J. (1988) The effects of cold immersion and hand protection on grip strength. Aviation Space & Environmental Medicine 59: 738-41. Tipton, M. J., Franks, C. M., Gennser, M. & Golden, F. St. C. (1999) Immersion death and deterioration in swimming performance in cold water. The Lancet Vol 354 (Fast track) 21 Aug: 626-9.

Mike_Tipton20 karma

No, sorry.

Mike_Tipton30 karma

I am conscious that in some of my answers I am giving references to scientific papers. You can find at least the abstracts to these at: https://www.ncbi.nlm.nih.gov/pubmed, or you can go to my Researchgate page and look under "Contributions" then "Chapters" to get more information: https://www.researchgate.net/profile/Mike_Tipton

Reference_account229 karma

Hello Professor Tipton, My question is the following:

What is the absolute worst thing that a person can do should they accidentally get stuck in very cold water?

Mike_Tipton58 karma

Thrash about or swim hard - best to rest as much as possible until your breathing is under control. Then continue to rest because exercise in cold water if wearing just normal clothes makes you cool more quickly than if you stay still. This is another way a life jacket helps - prevents you having to do so much exercise. If you have to exercise (to get to a much better situation) leg-only exercise is best.

Numooreswim27 karma

Mike, Nuala Moore here, My question is on the impact of cold water immersion on the cognitive responses of the swimmer.

There is real evidence from channel and Ice swimming that after a certain time swimming in cold water (shorter times at ice temps) swimmer face in cold water where the swimmers loses the ability to reason and or their decisions can be life threatening yet they continue to function (as in they continue to swim) -what is happening here physiological? and If I remember maybe you published this area.

Swimmers seem to have a different recollection of facts than the actual-yet they are still swimming.

Is it the case that swimmers in your opinion in long distance should be removed from the decision making process for the potential to "over shoot the runway"? For the safety outcome

How are they functioning swimming yet not able to respond cognitively?

Few incidents and just curious as to the impact on the ability to reason yet still function

Thanks

Mike_Tipton27 karma

Hello Nuala. With deep body cooling the first major organ to be affected is the brain and one of the first cognitive functions to be diminished is memory. This occurs at a temperature of about 33 °C, muscle function deteriorates at about 27 °C so it depends which comes first. In cold water with high levels of work (muscle heat production) the muscle may stay warm while the brain cools hence the swimming bu confused scenario. In NZ, Phil Rush (3-way Channel swimmer) has witnesses individuals swim to unconsciousness in the Cook Strait (personal communication). Add to this the possibility of insidious hypothermia and the fact that most people find it impossible to judge their deep body temperature when in cold water leads to the conclusion that: "Self-prescribed acute and chronic exposures to cold water may be dangerously wrong due to the inability to perceive body temperature" Better have observers witness the swimmers and know the early signs and symptoms of swim failure. https://www.wemjournal.org/article/S1080-6032(98)70923-8/pdf Tipton, M. J. & Bradford, C. (2014) Moving in extreme environments: open water swimming in cold and warm water Extreme Physiology & Medicine. 3:12. http://www.extremephysiolmed.com/content/3/1/12. Tipton, M. J., Franks, C. M., Gennser, M. & Golden, F. St. C. (1999) Immersion death and deterioration in swimming performance in cold water. The Lancet Vol 354 (Fast track) 21 Aug: 626-9.

gdj1125 karma

I don't do well in water that's even a little bit cold. In swimming pools in the summer when everyone is swimming and having fun, many times my lips would turn blue and I'd be miserable. Almost every time I've swam in the Pacific Ocean on the west cost of the USA the same thing would happen to me, even when everybody else seems fine. Is this because I don't have enough body fat, or am I just more prone to getting cold? Would this affect my ability to survive if I fell into very cold water?

Mike_Tipton31 karma

I could be that you are a bit cold sensitive. Difficult to say about the impact of your body morphology without seeing your data. However, ectomorphs (tall, long-limbed, thin people) cool more quickly in cold water.

bhadau820 karma

Why is a drowning human seems more powerful than normal?

Mike_Tipton43 karma

Panic releases stress hormones, including adrenaline which optimises the body for action.

roffvald17 karma

I spent some time in Antarctica on ships, once we did a Penguin swim where we jumped off the ships side in an opening in an ice floe, the water temp was -2C(We had rescue boats in the water, and lines + the crane on standby, and the sauna pre-heated) we only wore basic swimwear. How long could we have stayed in that water until we reached severe hypothermia? We were told 4-7 minutes.

Mike_Tipton19 karma

My worry would be cold shock and physical incapacitation (see other answers). Adults unlikely to become hypothermia within 30 minutes during a head-out immersion even in very cold water.

tankpuss15 karma

Other than "don't be in the water in the first place", "hold onto the neck of your life vest if you have to jump in" and "don't swim, only float".. what other advice do you have for surviving cold water immersion?

Mike_Tipton25 karma

See other answers. You must mitigate the 4 stages of immersion associated with specific hazards 1. Initial immersion (cold shock, autonomic conflict) 2. Short term incapacitation - neuromuscular cooling 3. Hypothermia 4. Circum-rescue collapse.

trailangel47 karma

Background to my question: I work within an agency that handles a lot of swift water rescues and recoveries, in glacial fed streams and rivers, and one thing that's always fascinated me is that, is how quickly someone in the cold river will die, compared to someone in the lake. Is it due to loss of heat or loss of energy? Is an instinctual dive reflex, wherein the heart slows dramatically when the body gets dunked, actually hurting someone who's fallen in a swift water environment because it's not giving their muscles enough oxygenated blood to swim as hard as they might need to?

Mike_Tipton8 karma

Difficult to say precisely. A river, because of its flow results in higher levels of convective cooling and probably requires greater effort as people try and reach the shore/stay afloat - these factors will result in faster cooling and cooling-related neuromuscular incapacitation and, when compounded by the great work rate, earlier exhaustion. Periodic immersion of the face and stress in this situation can result in what we have called "Autonomic Conflict" which results in cardiac problems. In a lake I guess folk can just relax back and await rescue? This means the stress levels, rates of cooling and cardiac consequences are very different and greater in a river. Shattock, M & Tipton, M. J. (2012) “Autonomic conflict”: a different way to die on immersion in cold water? Journal of Physiology. 590 (Pt 14): 3219-30

thechairinfront7 karma

I spent quite some time during the winters out on the lakes ice fishing. I'm familiar with when I should and shouldn't go out but what should I do in the event of falling through or someone else falling through? Generally you have less than 3 minutes before someone succumbs to hypothermia.

Mike_Tipton8 karma

Hypothermia is defined as a deep body temperature below 35 °C (2 °C below normal). In adults, with all their body mass and thermal inertia, it takes some time to lose enough heat to become hypothermic, so you have longer than 3 minutes before you become hypothermic. But you may become quickly incapacitated due to cooling of your limb nerves and muscle. The best thing to do is rest until you get you breathing back under control (about a minute) and then head back out of the ice the way you were coming when you went in i.e. where it was thick enough to support you before you fell in.
https://www.youtube.com/watch?v=QKpAzvXSldA

LeftIsAmerican6 karma

So do you jump in all at once or do you start with your toe and sneak your way into the water?

Mike_Tipton11 karma

Go in slowly if possible; the cold shock response demonstrates temporal and spatial summation so the slower you go in and the smaller the surface area you put in the smaller the response.

Salad_Fries5 karma

What are the psychological effects of being plunged into cold water. How long does the cold water shock last for?

Would Jack and Rose have been able to think coherently enough actually seek out/swim to the door?

Mike_Tipton13 karma

Cold shock lasts 1-2 minutes. Many of the physiological responses are similar to those seen with panic (increased heart rate, hyperventilation) but it is driven by a sudden fall in skin temperature and pat of our "fight or flight" response. There is a decrease in blood flow to the brain which may account for confusion in the first minutes of immersion. It is certainly difficult to swim at this time and best to stay still until your breathing is back under control - hence the RNLI Respect the Water advice to "float to live". https://www.youtube.com/watch?v=jncVb2onYC4

Northern_Ivy5 karma

Do you find that the 50/50/50 rule applies in most cases? You have a 50% chances of surviving 50 mins in 50*F water?

Mike_Tipton2 karma

See answer to RopeyChris.

Simmonsdude5 karma

Which Movie or TV do you think has gotten it right in terms of what happens when in the water?

Mike_Tipton5 karma

I suspect the death of Daniel Blake in the film "I, Daniel Blake (2016)" accurately depicted Autonomic Conflict.

taintlesswinner4 karma

How long does being habituated to cold water last? For example, how long would it take for a cold water swimmer who is no longer swimming to become unhabituated?

Mike_Tipton7 karma

Half of the habituation of the cold shock response lost after 14 months - no data after that. Tipton, M. J., Mekjavic, I. B. & Eglin, C. M. (2000) Permanence of the habituation of the initial responses to cold-water immersion. European Journal of Applied Physiology 83:17-21.

CreamyRook3 karma

Have you ever been contacted to give expert advice in special situations in the same way all those survival experts were contacted in the Thailand cave scenario?

Mike_Tipton12 karma

Yes, I get contacted quite a bit. I was contacted about the boys in the cave and about the recent lady who spent 10 hours in the Adriatic. https://www.bbc.co.uk/news/uk-45244269

PhillipBrandon1 karma

How cold is "cold"?

At what temperature does water merit special thermal consideration?

Mike_Tipton8 karma

There is no strict definition of cold water, but many use <15 °C as the threshold.