The Science of Thirst: Understanding How Your Body Signals for Hydration

Get to know your body’s thirst signals so you can hydrate before it’s too late.

  • Published: 6/9/2023
  • 4 min. read

Picture yourself walking across a desert with the sun beating down. Your mouth is dry as sand, skin shriveling up, and you’re feeling fatigue like you’ve never had before. You’re anticipating the sensation of water touching your tongue like it's the best thing that could ever happen to you. Hopefully you’re not in this situation! But you can likely relate to common symptoms of dehydration or thirst. 

Thirst is the craving for fluids that happens when we start to run low on water. This natural response prevents us from reaching harmful levels of dehydration and is regulated by communication between our bodies and brains. 

Why do we need water?

Water is a nutrient that’s required on a daily basis for optimal functioning. It regulates our body processes including temperature, brain and nerve function, and getting rid of waste. It also helps us absorb nutrients, improves our skin, and fights fatigue. To emphasize just how important it is, research suggests that even mild dehydration levels, losing 1-2% of body water, can impair our cognitive abilities and physical performance (1). Check out more reasons why to up your water game here: All the Reasons You Should Drink More Water

The science of thirst 

You know that super satisfying sensation when we take a swig of water after what feels like an eternity without it? Our bodies innately know when it’s time to take that drink in order to deter dehydration. But how does this work?

We consistently lose water through functions such as metabolism, breathing, removing wastes, and sweating. When our body is healthy, it will signal to us when we need to replenish these lost stores. When fluid levels shift, our brain cells, or lamina terminalis neurons, sense this change and signal that it's time for more (2). 

We also have a pleasant experience when we drink water, in order to encourage having it on a regular basis. In mice studies, scientists found that a special sensor glows in the presence of the rewarding molecule called dopamine. They found that there was a large spike in dopamine when thirsty mice drank both water and salty solutions (3). 

When it comes to regulating how much to have, there’s an additional mechanism in our throat and digestive system which signals the presence of water. Your kidneys, which help control urination, can either conserve water if you’re dehydrated, or make more urine to get rid of excess water (4). However, even if you have healthy kidney function, too much water can be harmful. That’s because very high amounts of water can disrupt electrolyte balance. 

This intricate feedback loop gets weaker as we get older. So it’s important to note that as you age, hitting the hydrating drinks before you notice signals may be necessary.

How much water to drink per day

The amount of water we need depends on many factors such as our age, activity level, foods we eat, and climate. Typically, we get about 20% of the fluids we need from foods and the other 80% from beverages. Which is why The National Academy of Medicine recommends about 13 cups (8 ounces each) for men and 9 cups for women including food sources (5).

Top tips to stay hydrated

Keep a cup

Keeping a water bottle of glass with you can be a reminder to drink more. If you’re working or going to school, put it on your desk to be reminded to have more. Try placing a glass or bottle near your bed so you see it right as you wake up. When you have a meal, order water and try to have at least a glass. 

Add a twist 

Since water doesn’t have flavor, it may be more enjoyable if you add some flare to it. There are many infused water brands on the market but oftentimes they are expensive and some contain artificial ingredients or added sugar. Try flavoring your own by adding slices of lemon, lime or orange. Sliced cucumber makes for a cooling effect while ginger can add some zest. Some refreshing herbs like fresh mint or basil are also great!

Use a tracker

It can be easy to forget to drink, especially as those signals begin to decrease as we age. Using an app to remind you can help keep you accountable. In fact, studies have suggested that reminders can significantly increase water intake; and decrease sedentary time as a bonus (6). So try using a tracker like Lifesum today!

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