Water is essential for human health. A person can’t survive more than a few days without water, and adequate daily hydration is vital to keeping the body functioning properly.
While it’s more common to think about hydration in the context of diet and exercise, an increasing amount of research is exploring the links between hydration and sleep.
Dehydration may create barriers to sleep, and insufficient sleep may increase the chances of being dehydrated. At the same time, too much fluid intake can cause excess urination that may lead to sleep interruptions.
Finding the right balance of fluid intake can improve overall health and may contribute to better sleep without numerous trips to the bathroom or waking up feeling dehydrated.
Hydration is important for most systems of the body, which is why dehydration can have diverse symptoms, including effects on sleep.
People who are suffering from significant dehydration often find that they feel extremely tired, lethargic, or fatigued. Other symptoms of dehydration, such as headaches, dry mouth and nasal passages, and muscle cramps may cause discomfort that makes it harder to sleep well.
At the same time, excess hydration can contribute to sleeping problems. Frequent urination at night, known as nocturia, can interrupt sleep with repeated trips to the bathroom. Nocturia can be especially problematic for people who struggle to fall back asleep after getting up from bed.
There is also evidence that a lack of sleep may contribute to dehydration. In a study of nearly 20,000 adults in both the United States and China, people who slept only six hours per night were found to have significantly higher rates of dehydration than people who slept eight hours.
While this was an observational study and cannot prove causality, that the association existed in two distinct cultural contexts adds weight to the findings. In addition, there are potential biological explanations for why poor sleep can affect hydration.
Most water loss happens through urination, but the body also loses fluid through the skin and from respiration, which is known as insensible water loss. Over a full day, about 300-400 milliliters of water are lost from breathing. A large component of that loss happens during sleep, although the amount can depend on whether a person breathes primarily through their mouth or nose.
During sleep, there is no fluid intake to make up for insensible water loss, which is why it is believed that the body’s internal clock, or circadian rhythm, kicks in to manage a balanced level of hydration. In the latter part of sleep, circadian signals cause the body to produce a hormone called vasopressin that promotes water retention.
If sleep is interrupted or cut short, though, this natural process may be disrupted, interfering with the hormonal signals for water retention. As a result, sleep deprivation may directly contribute to dehydration.
It’s normal for the body to have a net loss in water during the night, but there are steps that you can take to keep that from resulting in dehydration.
Getting a sufficient amount of high-quality sleep is an important part of preventing dehydration. The body goes through multiple complex processes during sleep that enable recovery for overall health. By sleeping the recommended amount, you allow these processes to unfold and let your circadian rhythm better manage your body’s fluid levels.
Sleeping well often starts by making sleep a priority. A common principle of sleep hygiene is having a consistent sleep schedule that provides enough time for you to get the sleep that you need. Limiting late-night use of electronic devices, developing a relaxing bedtime routine, and using a comfortable mattress are other examples of positive sleep hygiene that can help you rest well.
If you frequently find yourself thirsty at night, it might mean that you aren’t staying hydrated during the day. By maintaining hydration throughout the day, you have less to worry about when bedtime rolls around. Tips for healthy hydration include:
Sweating can cause water loss at night, and if your bedroom is too warm or you tend to sleep hot, heavy sweating can make it more likely that you’ll wake up dehydrated.
To avoid this, try to make sure that you can easily maintain a comfortable temperature through the night. Most experts recommend keeping your bedroom thermostat on the cooler side. You can also wear light, loose clothing and use breathable bedding that keeps you from overheating.
A common challenge is knowing how to stay hydrated during sleep without having to frequently wake up at night to go to the bathroom. Several tips can help you avoid both dehydration and excess trips to the bathroom:
In some cases, it may be unavoidable that you’ll have to wake up at least once in the night to pee. This is normal for many people and becomes more common with aging and some medical conditions or medications.
In this situation, it’s important to make it as easy as possible to get back to sleep after you return to bed. Some simple tips that can help with falling back asleep include:
If you have concerns about regular dehydration, poor sleep, or frequent nighttime trips to the bathroom, talk with your doctor. Reviewing your situation can help determine if any underlying medical condition is present that may explain your symptoms. Your doctor can also make specific recommendations for your diet and daily water consumption.