Water is essential for daily functioning and health, and we can only survive a few days without it. Yet we constantly lose water through sweat, urination and even evaporation when we breathe.

This is why we have evolved a way to regulate and maintain water in our bodies. Like other animals, our survival relies on a strong biological drive that tells us to find and drink water to balance fluid loss.

This is thirst – a sensation of dryness in the mouth signalling we need to have a drink. This basic physiological mechanism is controlled mainly by part of the brain’s “control centre”, called the hypothalamus. The hypothalamus receives signals from various regions of the body and in return, releases hormones that act as a messenger to signal the thirst sensation.

What is dehydration?

Staying hydrated (having enough water in our bodies) is important for several reasons, including:

• regulating body temperature through sweat and respiration
• lubricating joints and eyes
• preventing infections
• digesting and absorbing nutrients
• flushing out waste (via the kidneys)
• preventing constipation
• brain function (including memory and concentration)
• mood and energy levels
• physical performance and recovery from exercise
• skin health.

Dehydration occurs when our body doesn’t have enough water. Even slight drops in fluid levels have noticeable consequences, such as headaches, feeling dizzy, lethargy and struggling to concentrate.

Chronic dehydration can pose more serious health risks, including urinary tract infections, constipation and kidney stones.

What does the evidence say?

Despite thirst being one of the most basic biological drivers for good hydration, science suggests our feelings of thirst and subsequent fluid intake don’t always correlate with hydration levels.

For example, a recent study explored the impact of thirst on fluid intake and hydration status. Participants attended a lab in the morning and then later in the afternoon to provide markers of hydration status (such as urine, blood samples and body weight). The relationship between levels of thirst in the morning and afternoon hydration status was negligible.

Further, thirst may be driven by environmental factors, such as access to water. For example, one study looked at whether ample access to water in a lab influenced how much people drank and how hydrated they were. The link between how thirsty they felt and how hydrated they were was weak, suggesting the availability of water influenced their fluid intake more than thirst.

Exercise can also change our thirst mechanism, though studies are limited at this stage.

Interestingly, research shows women experience thirst more strongly than men, regardless of hydration status. To understand gender differences in thirst, researchers infused men and women with fluids and then measured their thirst and how hydrated they were. They found women generally reported thirst at a lower level of fluid loss. Women have also been found to respond more to feeling thirsty by drinking more water.

Other ways to tell if you need to drink some water

While acknowledging some people will need to drink more or less, for many people, eight cups (or two litres) a day is a good amount of water to aim for.

But beyond thirst, there are many other ways to tell whether you might need to drink more water.

1. urine colour: pale yellow urine typically indicates good hydration, while darker, concentrated urine suggests dehydration

2. frequency of going to the toilet: urinating regularly (around four to six times a day) indicates good hydration. Infrequent urination can signal dehydration

3. skin turgor test: gently pinching the skin (for example, on the back of the hand) and observing how quickly the skin returns to its normal position can help assess hydration. Slow return may indicate dehydration

4. mouth and lips: a dry mouth or cracked lips can be early signs of dehydration

5. headaches and fatigue: frequent headaches, dizziness, or unexplained fatigue can be signs of inadequate hydration

6. sweating: in physically active people, monitoring how much they sweat during activity can help estimate fluid loss and hydration needs. Higher levels of sweat may predispose a person to dehydration if they are unable to replace the fluid lost through water intake

These indicators, used together, provide a more comprehensive picture of hydration without solely depending on the sensation of thirst.

Of course, if you do feel thirsty, it’s still a good idea to drink some water.

Lauren Ball, Professor of Community Health and Wellbeing, The University of Queensland and Kiara Too, PhD candidate, School of Human Movement and Nutrition Sciences, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

One in three of us will develop cancer at some point in our lives. But survival rates have improved to the point that two-thirds of those diagnosed live more than five years.

This extraordinary shift over the past few decades introduces new challenges. A large and growing proportion of people diagnosed with cancer are living with it, rather than dying of it.

In our recently published research we examined the cancer experiences of 81 New Zealanders (23 Māori and 58 non-Māori).

We found survivorship not only entailed managing the disease, but also “wrangling” a complex health system.

Surviving disease or surviving the system

Our research focused on those who had lived longer than expected (four to 32 years since first diagnosis) with a life-limiting or terminal diagnosis of cancer.

Common to many survivors’ stories was the effort it took to wrangle the system or find others to advocate on their behalf, even to get a formal diagnosis and treatment.

By wrangling we refer to the practices required to traverse complex and sometimes unwelcoming systems. This is an often unnoticed but very real struggle that comes on top of managing the disease itself.

The common focus of the healthcare system is on symptoms, side effects of treatment and other biological aspects of cancer. But formal and informal care often falls by the wayside, despite being key to people’s everyday experiences.

The inequities of cancer survivorship are well known. Analyses show postcodes and socioeconomic status play a strong role in the prevalence of cancer and survival.

Less well known, but illustrated in our research, is that survival is also linked to people’s capacity to manage the entire healthcare system. That includes accessing a diagnosis or treatment, or identifying and accessing alternative treatments.

Survivorship is strongly related to material resources, social connections, and understandings of how the health system works and what is available. For instance, one participant who was contemplating travelling overseas to get surgery not available in New Zealand said:

We don’t trust the public system. So thankfully we had private health insurance […] But if we went overseas, health insurance only paid out to $30,000 and I think the surgery was going to be a couple of hundred thousand. I remember Dad saying and crying and just being like, I’ll sell my business […] we’ll all put in money. It was really amazing.

Assets of survivorship

In New Zealand, the government agency Pharmac determines which medications are subsidised. Yet many participants were advised by oncologists or others to “find ways” of taking costly, unsubsidised medicines.

This often meant finding tens of thousands of dollars with no guarantees. Some had the means, but for others it meant drawing on family savings, retirement funds or extending mortgages. This disproportionately favours those with access to assets and influences who survives.

But access to economic capital is only one advantage. People also have cultural resources – often described as cultural capital.

In one case, a participant realised a drug company was likely to apply to have a medicine approved. They asked their private oncologist to lobby on their behalf to obtain the drug through a compassionate access scheme, without having to pay for it.

Others gained community support through fundraising from clubs they belonged to. But some worried about where they would find the money, or did not want to burden their community.

I had my doctor friend and some others that wanted to do some public fundraising. But at the time I said, “Look, most of the people that will be contributing are people from my community who are poor already, so I’m not going to do that option”.

Accessing alternative therapies, almost exclusively self-funded, was another layer of inequity. Some felt forced to negotiate the black market to access substances such as marijuana to treat their cancer or alleviate the side effects of orthodox cancer treatment.

Cultural capital is not a replacement for access to assets, however. Māori survivorship was greatly assisted by accessing cultural resources, but often limited by lack of material assets.

Persistence pays

The last thing we need when faced with the possibility of cancer is to have to push for formal diagnosis and care. Yet this was a common experience.

One participant was told nothing could be found to explain their abdominal pain – only to find later they had pancreatic cancer. Another was told their concerns about breathing problems were a result of anxiety related to a prior mental health history, only to learn later their earlier breast cancer had spread to their lungs.

Persistence is another layer of wrangling and it often causes distress.

Once a diagnosis was given, for many people the public health system kicked in and delivered appropriate treatment. However, experiences were patchy and variable across New Zealand.

Issues included proximity to hospitals, varying degrees of specialisation available, and the requirement of extensive periods away from home and whānau. This reflects an ongoing unevenness and lack of fairness in the current system.

When facing a terminal or life-limiting diagnosis, the capacity to wrangle the system makes a difference. We shouldn’t have to wrangle, but facing this reality is an important first step.

We must ensure it doesn’t become a continuing form of inequity, whereby people with access to material resources and social and cultural connections can survive longer.

Kevin Dew, Professor of Sociology, Te Herenga Waka — Victoria University of Wellington; Alex Broom, Professor of Sociology & Director, Sydney Centre for Healthy Societies, University of Sydney; Chris Cunningham, Professor of Maori & Public Health, Massey University; Elizabeth Dennett, Associate Professor in Surgery, University of Otago; Kerry Chamberlain, Professor of Social and Health Psychology, Massey University, and Richard Egan, Associate Professor in Health Promotion, University of Otago

This article is republished from The Conversation under a Creative Commons license. Read the original article.