Jennifer Corso, upstream marketing physiologist (sensors), Rockley Photonics explains how wearable devices can let you monitor hydration, and ultimately lead to healthier living.
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Water - concept of hydration
Phoenix can get hot. Very hot. With the rapid expansion of the city, the valley in which it rests has been slowly transforming into an urban heat sink. As a Phoenix resident, I’m well acquainted with the threat to human health that extreme heat may present. Just in Arizona, many people will fall victim to heat-related illnesses this summer, especially people who fail to hydrate properly. Some of them will die. In 2020, there were 520 heat-related deaths in Arizona, and in June of 2021, severe heat illness was responsible for 53 fatalities in Maricopa County alone during a single week.
But maintaining an appropriate hydration level is essential for a healthy life at any time of the year. A person’s hydration status can significantly impact many aspects of their well-being, including mood, physical performance, kidney function, skin condition, and even mental state and cognition. The elderly are at a significantly higher risk for dehydration due to cognitive decline, inadequate care, and/or physiological changes associated with both aging and comorbidities, such as poor kidney function and thirst response.
Despite these well-understood health implications, most people across the U.S. still don’t drink enough water. The National Health and Nutrition Examination Survey studied 4,000 children in the U.S. between the ages of 6 and 19 from 2009 to 2012. The study showed that more than half of children and adolescents failed to stay adequately hydrated.
The problem is similar among adults, especially for the “weekend warriors” and amateur athletes who love to stay active. The sad truth is that most people have no idea how to stay properly hydrated.
Thinking about drinking
It’s easy to say, “stay hydrated,” but maintaining healthy and mindful hydration habits can be hard. Most people who are not high-performance athletes don’t have access to the tools or analytics necessary to measure their hydration level on a routine basis to see if their habits are adequate to optimise a state of health and wellbeing. Indeed, other than fluid analysis, only a few indicators of hydration level are available to the general population.
The sensation of thirst is one. But it’s a lagging indicator, providing only a rough approximation of when to drink, frequently after it may be a bit too late. By the time you feel thirsty, your body has probably already lost nearly 2% of its fluid — a state of mild dehydration. To maintain proper hydration, individuals should drink water long before they feel thirsty. If, for example, you’re in the middle of a long run or a bike race and you realise you’re thirsty, then you’re probably beyond the point of quickly rehydrating yourself. As a result, your performance will likely suffer.
Other indicators of hydration status are urine color and output. Darker urine and lower output are typically indicative of dehydration. However, these are also imprecise ways of measuring hydration. Even clinical methods of assessing fluid status have limitations. Part of the problem is that every person is different. Some people need more fluids than others. Some people can drink less without becoming dehydrated.
In addition to the immediate effects of dehydration, there can often be long-term consequences. Dehydration has been directly linked to be one of the causes of kidney stones. It also plays a role in the development of certain cardiovascular diseases. Dehydration can also impair cognitive performance and lead to more frequent symptoms of depression and anxiety. A study conducted in Iran showed that adults who drank less water had a higher risk of anxiety and depression than those who drank more water.
There are also highly active groups who are overly focused on drinking water and tend to hyperhydrate. This is commonly seen in competitive athletes and military personnel. Also known as overhydration, hyperhydration can reduce the relative amount of sodium and other electrolytes in the blood. This can cause mild problems like nausea, or in severe cases like water intoxication, life-threatening consequences like seizures or coma.
Whether considering the case of dehydration or hyperhydration, because of the individual differences and variability among our planet’s 8 billion inhabitants, there are many complicated nuances to understanding and managing hydration.
Measuring your hydration for better health
Providing people with a way to measure their hydration levels in a non-invasive and routine manner can equip them with important insights about their hydration status — and thereby yield many significant benefits. But it needs to be done in a way that’s cost-effective and easily accessible for everyone.
One way to generate these insights is through a platform that measures key biomarkers in real time using a wearable device. An emerging technology that could enable this capability is a miniaturised photonics-based sensor that can measure water concentration changes in the human body non-invasively. This new type of sensor generates multiple laser wavelengths that penetrate the skin at varying depths to target water spectra features. The sensor leverages the principle that changes in the concentration of components within the skin (e.g., collagen, lipids, and water) can be observed by measuring the skin absorption spectra. As the water in the dermis diminishes, the concentration of solutes becomes higher, changing the overall skin absorption spectra.
Armed with such hydration-assessment capabilities, a wearable device would give people the potential to understand their hydration status in an unprecedented way. For example, with a quick glance at their wrist, people could see that their hydration levels are trending downward — and avoid becoming dehydrated in the first place. Alternatively, if they become dehydrated during or after a bout of exercise, they could better determine how much they should drink to properly rehydrate. This kind of monitoring solution would benefit not only athletes, but also many others who may be more susceptible to dehydration, such as office workers toiling through their day, individuals who have fallen ill, and people who live at a higher altitude. People from nearly every walk of life could benefit by knowing if they’re drinking enough water for their individual body types and needs.
Having a wearable device that could track personal hydration levels is only part of the equation. It should also be easy for people to understand the information being tracked. One tool that could help accomplish this is a single index that simplifies the reporting of hydration levels and delivers insights and recommendations tailored to each person’s individual hydration needs. Solutions such as this could help improve our ability to manage hydration. Being properly hydrated, whether in the gym or at the office, can help sharpen your focus and improve your overall performance.
Smart devices for smart drinking
Tracking water consumption and maintaining healthy hydration are not always easy in the hectic lives that many people live today. However, if empowered with the ability to monitor hydration on a routine basis, smartwatches and other wearables could provide actionable information that helps people improve their lifestyle habits.
Already, leading device manufacturers have started to explore the integration of biomarker sensors to track hydration levels. These forward-looking companies understand that hydration and other healthy behaviors are driven by routine — and that providing contextual cues can trigger “automatic” responses and help people make positive changes in their behaviour.
By enabling the non-invasive measurement of hydration on a routine basis, a wearable biomarker-sensing solution would have the potential to provide timely recommendations for managing personal hydration — recommendations tailored to the specific needs of each individual. Empowered with these insights, we could all make better-informed decisions about our hydration, health, and well-being.
