Should you drink water before bed?

Water is essential for life, just like sleep. Every day, we lose water through processes such as urination, breathing, and sweating—even while we sleep. During the night, our bodies don’t take in any water, which can lead to slight dehydration. This is why many people wake up feeling thirsty.¹ 

When we sleep, our bodies release a hormone called vasopressin, which helps the kidneys reabsorb water and keep us hydrated.²  However, if your sleep is disrupted, this natural process is thrown off, potentially leading to dehydration,² which is why staying hydrated is necessary for a good night’s rest.

How hydration affects sleep

Hydration and sleep are closely linked, but they must be in equilibrium. Drinking too much water before bed can cause frequent trips to the bathroom, which will disturb your sleep. On the other hand, not drinking enough water can also affect how well you sleep, but in different ways.

Regulating body temperature: Water helps regulate your body temperature, and this is important for getting a good night’s sleep.³ When you are dehydrated, your body struggles to dissipate heat, making it harder to maintain a comfortable temperature. If you don’t drink enough water, you may wake up thirsty, interrupting your sleep to quench that thirst.

Supporting brain function: Water is essential for many bodily functions, including brain function. Dehydration can impair cognitive processes such as mood regulation, memory, and stress response, which can affect your ability to sleep.⁴ When your brain isn’t functioning at its best, it becomes harder to wind down and fall asleep at night.

Preventing headaches: Dehydration is a well-known trigger for headaches, and headaches can significantly impact your ability to sleep. Drinking enough water can help prevent dehydration headaches.⁵ If untreated, headaches can wake you up at night or make it difficult to fall asleep, making hydration all the more important before bedtime.

The dangers of overhydration

While staying hydrated is important, drinking too much water can also cause problems. Overhydration before bed often leads to frequent bathroom trips during the night, which disrupts your sleep cycle.⁶ 

Drinking too much water can also throw off your body’s natural processes. Your kidneys may struggle to balance water levels, which can dilute sodium in your blood, leading to a condition called hyponatraemia, the symptoms of which include confusion, headaches, and cramps—all culprits of poor sleep.⁶

Avoiding dehydration during sleep

It’s normal to lose water while you sleep, but there are steps you can take to avoid dehydration from affecting your rest. By prioritising hydration and sleep, you can ensure your body functions properly and you wake up feeling refreshed.

1. Make sleep a priority

You need to sleep adequately so that your body can go through its natural processes, including regulating hydration. Ensuring you get enough rest not only helps prevent dehydration but also allows your body to recharge and perform at its best. If you’re struggling with poor sleep, consider creating a better sleep routine by limiting screen time before bed, setting a regular bedtime, and avoiding caffeine late in the day.

1. Stay hydrated throughout the day

Dehydration often stems from neglecting to drink enough water during the day. If you wake up feeling excessively thirsty, it may be a sign that you aren’t drinking enough. To prevent dehydration, try sipping water regularly throughout the day. Keeping a water bottle with you can serve as a reminder to stay hydrated—but remember not to overdo it, as drinking too much water at night can be counterintuitive.

1. Choose water over other drinks

While it’s fine to enjoy other beverages, swapping sugary or caffeinated drinks for water can make a big difference. Choosing water more often ensures that your body gets the hydration it needs without the side effects that other drinks can bring, like caffeine-induced sleep disruptions.

1. Add hydrating foods to your diet

Many fruits and vegetables have a high water content and can contribute to your daily hydration. Foods like cucumbers, melons, and leafy greens are excellent choices to boost your water intake while also providing other essential nutrients. Add these to your diet to stay hydrated without having to rely solely on drinking water.

Finding balance for better sleep

It’s all about balance when it comes to hydration and sleep. While drinking too much water before bed can lead to night-time trips to the bathroom, not drinking enough can cause dehydration-related sleep issues. Reduce your fluid intake in the hour or two before bed to prevent disturbances during the night.

In the morning, start your day with a glass of water to rehydrate after hours of sleep. This can help replace fluids lost overnight and get you on the right track for a well-balanced day.

The numan take

While too much water at night can keep you awake, too little can disrupt your body in ways that affect your sleep long-term. Keep a water bottle by your side throughout the day to stay hydrated and ensure that your body functions at its best.

References

1. Weissenberg S. Insensible water loss during sleep: A theoretical exercise. Adv Physiol Educ [Internet]. 2005;29(4):213–5. Available from: http://dx.doi.org/10.1152/advan.00028.2005

2. Török B, Varga J, Zelena D. Vasopressin as a possible link between sleep-disturbances and memory problems. Int J Mol Sci [Internet]. 2022;23(24). Available from: http://dx.doi.org/10.3390/ijms232415467

3. Popkin BM, D’Anci KE, Rosenberg IH. Water, hydration, and health. Nutr Rev [Internet]. 2010;68(8):439–58. Available from: http://dx.doi.org/10.1111/j.1753-4887.2010.00304.x

4. Masento NA, Golightly M, Field DT, Butler LT, van Reekum CM. Effects of hydration status on cognitive performance and mood. Br J Nutr [Internet]. 2014 [cited 2024 Sep 25];111(10):1841–52. Available from: https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/effects-of-hydration-status-on-cognitive-performance-and-mood/1210B6BE585E03C71A299C52B51B22F7

5. Price A, Burls A. Increased water intake to reduce headache: learning from a critical appraisal. J Eval Clin Pract [Internet]. 2015;21(6):1212–8. Available from: http://dx.doi.org/10.1111/jep.12413

6. Hew-Butler T, Smith-Hale V, Pollard-McGrandy A, VanSumeren M. Of mice and men-the physiology, psychology, and pathology of overhydration. Nutrients [Internet]. 2019;11(7). Available from: http://dx.doi.org/10.3390/nu11071539