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.

You may have seen some new ways to describe when someone is autistic and also has attention-deficit hyperactivity disorder (ADHD). The terms “AuDHD” or sometimes “AutiADHD” are being used on social media, with people describing what they experience or have seen as clinicians.

It might seem surprising these two conditions can co-occur, as some traits appear to be almost opposite. For example, autistic folks usually have fixed routines and prefer things to stay the same, whereas people with ADHD usually get bored with routines and like spontaneity and novelty.

But these two conditions frequently overlap and the combination of diagnoses can result in some unique needs. Here are five important things to know about AuDHD.

1. Having both wasn’t possible a decade ago

Only in the past decade have autism and ADHD been able to be diagnosed together. Until 2013, the Diagnostic and Statistical Manual of Mental Disorders (DSM) – the reference used by health workers around the world for definitions of psychological diagnoses – did not allow for ADHD to be diagnosed in an autistic person.

The manual’s fifth edition was the first to allow for both diagnoses in the same person. So, folks diagnosed and treated prior to 2013, as well as much of the research, usually did not consider AuDHD. Instead, children and adults may have been “assigned” to whichever condition seemed most prominent or to be having the greater impact on everyday life.

2. AuDHD is more common than you might think

Around 1% to 4% of the population are autistic.

They can find it difficult to navigate social situations and relationships, prefer consistent routines, find changes overwhelming and repetition soothing. They may have particular sensory sensitivities.

ADHD occurs in around 5–8% of children and adolescents and 2–6% of adults. Characteristics can include difficulties with focusing attention in a flexible way, resulting in procrastination, distraction and disorganisation. People with ADHD can have high levels of activity and impulsivity.

Studies suggest around 40% of those with ADHD also meet diagnostic criteria for autism and vice versa. The co-occurrence of having features or traits of one condition (but not meeting the full diagnostic criteria) when you have the other, is even more common and may be closer to around 80%. So a substantial proportion of those with autism or ADHD who don’t meet full criteria for the other condition, will likely have some traits.

3. Opposing traits can be distressing

Autistic people generally prefer order, while ADHDers often struggle to keep things organised. Autistic people usually prefer to do one thing at a time; people with ADHD are often multitasking and have many things on the go. When someone has both conditions, the conflicting traits can result in an internal struggle.

For example, it can be upsetting when you need your things organised in a particular way but ADHD traits result in difficulty consistently doing this. There can be periods of being organised (when autistic traits lead) followed by periods of disorganisation (when ADHD traits dominate) and feelings of distress at not being able to maintain organisation.

There can be eventual boredom with the same routines or activities, but upset and anxiety when attempting to transition to something new.

Autistic special interests (which are often all-consuming, longstanding and prioritised over social contact), may not last as long in AuDHD, or be more like those seen in ADHD (an intense deep dive into a new interest that can quickly burn out).

Autism can result in quickly being overstimulated by sensory input from the environment such as noises, lighting and smells. ADHD is linked with an understimulated brain, where intense pressure, novelty and excitement can be needed to function optimally.

For some people the conflicting traits may result in a balance where people can find a middle ground (for example, their house appears tidy but the cupboards are a little bit messy).

There isn’t much research yet into the lived experience of this “trait conflict” in AuDHD, but there are clinical observations.

4. Mental health and other difficulties are more frequent

Our research on mental health in children with autism, ADHD or AuDHD shows children with AuDHD have higher levels of mental health difficulites than autism or ADHD alone.

This is a consistent finding with studies showing higher mental health difficulties such as depression and anxiety in AuDHD. There are also more difficulties with day-to-day functioning in AuDHD than either condition alone.

So there is an additive effect in AuDHD of having the executive foundation difficulties found in both autism and ADHD. These difficulties relate to how we plan and organise, pay attention and control impulses. When we struggle with these it can greatly impact daily life.

5. Getting the right treatment is important

ADHD medication treatments are evidence-based and effective. Studies suggest medication treatment for ADHD in autistic people similarly helps improve ADHD symptoms. But ADHD medications won’t reduce autistic traits and other support may be needed.

Non-pharmacological treatments such as psychological or occupational therapy are less researched in AuDHD but likely to be helpful. Evidence-based treatments include psychoeducation and psychological therapy. This might include understanding one’s strengths, how traits can impact the person, and learning what support and adjustments are needed to help them function at their best. Parents and carers also need support.

The combination and order of support will likely depend on the person’s current functioning and particular needs. https://www.youtube.com/embed/pMx1DnSn-eg?wmode=transparent&start=0 ‘Up until recently … if you had one, you couldn’t have the other.’

Do you relate?

Studies suggest people may still not be identified with both conditions when they co-occur. A person in that situation might feel misunderstood or that they can’t fully relate to others with a singular autism and ADHD diagnosis and something else is going on for them.

It is important if you have autism or ADHD that the other is considered, so the right support can be provided.

If only one piece of the puzzle is known, the person will likely have unexplained difficulties despite treatment. If you have autism or ADHD and are unsure if you might have AuDHD consider discussing this with your health professional.

Tamara May, Psychologist and Research Associate in the Department of Paediatrics, Monash University

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