9 Things You’re Doing at Night That May Be Making You More Dehydrated in the Morning

Photo: Stocksy/Jimena Roquero
It’s perfectly customary to wake up feeling thirsty and slightly dehydrated. So, what causes dehydration? Well, your body continues to function throughout the night without hydrating, after all, and simple tasks like breathing and regulating body temperature as you sleep can result in fluid loss.

However, morning dehydration can be made more or less severe depending on your nighttime routine the evening prior—and you can often blame a lack of hydration for exacerbating symptoms and resulting in common dehydration signs, such as fatigue, a pounding headache, dry mouth, or parched skin that are making you feel anything but energized in the a.m. More intense dehydration means both more intense symptoms and an increase in the amount of time (and the quantity of fluids) your body will need to rebalance and restore hydration levels. And what's worse than feeling dehydrated, foggy, and low in energy for an entire day?

Experts In This Article

Luckily, you can reduce the likelihood of excess dehydration side effects in the morning by keeping an eye out for these sneaky (read: preventable) causes of dehydration that may be part of your evening routine.

What causes dehydration in the morning, according to an RD

1. Not drinking enough water throughout the day

While you may not want to chug water right before bed for the sake of your bladder (and, in turn, your sleep quality), you do want to make sure you’re well-hydrated during the earlier evening hours and throughout the day.

"If you aren’t well-hydrated and haven’t had enough water and fluids when going to bed, you will feel thirsty, and potentially wake up with a dry mouth or sore throat," says Trista Best, MPH, RD, LD. "Your pee may also have a strong odor or appear darker than normal." If your pee is dark yellow or orange in the morning, Best says that is an indicator that your hydration levels are way too low.

What is the fastest way to cure dehydration?

To prevent chronic dehydration symptoms, the best action step is to set reminders to drink more fluids and water with dinner, and in moderation before bed. Best also recommends incorporating more electrolyte-containing foods (such as Greek yogurt, bananas, peanut butter, and leafy greens) into your dinners and bedtime snacks. Electrolytes help maximize and replenish hydration stores to keep your body balanced as you sleep, leaving you with less of a deficit in the morning. On the flip side, electrolytes can also significantly help with dehydration recovery, if needed.

If your chronic dehydration is causing chest pain, dizziness, or shortness of breath, however, it's best to check in with your doctor to make sure nothing serious is going on.

2. Having a cocktail or glass of wine (or two) before bed

If you wake up feeling dizzy and lightheaded or you experience headaches, think about your beverage of choice the night before. “When you're drinking alcohol at night, you're less likely to be drinking water and other hydrating beverages. Alcohol also stops the body from releasing antidiuretic hormone, which leads to more water loss than usual and helps to explain your increased need to urinate during the night,” says Best. “Other signs of morning dehydration caused by alcohol can include dry skin, dry or cracked lips, and poor skin turgor—meaning when you pinch the skin on your hand, it doesn't return to its initial position."

To avoid this undesirable scenario (and the resulting hangover), alternate alcoholic beverages with a glass of water and avoid consuming more than the USDA's recommended one drink per day when possible. This will help to reduce the amount you’re drinking overall and to keep your body's hydration levels in check. So, how much water does it take to rehydrate while drinking? For reference, have a full glass of water for every 12 ounces of beer, five ounces of wine, or one-and-a-half ounces of spirits you consume.

3. The room is too toasty or your comforter is too heavy

Too warm of an environment or excess heat from blankets can cause dehydration; this is why we tend to wake up extra sweaty and thirsty during the summertime. “Cooler temperatures are better for sleep,” says Lauren Harris-Pincus, MS, RDN, founder of NutritionStarringYOU.com and author of The Everything Easy Pre-Diabetes Cookbook. “Sleeping in temperatures over 67° F may cause night sweats, which ultimately results in fluid and electrolyte losses." Harris-Pincus adds that dry winter air can also result in dehydration, leading you to wake up thirsty as a result. "Using a humidifier in the wintertime can help lessen fluid loss, too," she recommends.

Best agrees that cooler temperatures help your body stay hydrated. “For better sleep quality and decreased risk of dehydration, set the thermostat within a range of 60° F and 67° F, as this is what is recommended by the Sleep Foundation,” says Best. If you're unable to control the temperature of your home or don't have A/C, another good option is to sleep with a fan on or cracking a window open.

“Cotton bedding and heavy blankets can make dehydration more likely due to their sweat promoting nature, too,” Best says. If you're a hot sleeper, Best recommends trying silk or microfiber sheets, which are more cooling materials.

4. Your bedtime snack was super salty (or caffeinated)

Nothing's better than a pre-bed nosh, but the kind of food you’re snacking on at night can impact your hydration levels the following day. “Eating a salty or high-sodium snack before bed can lead to dehydration, as sodium is programmed to pull water from the cells and increase urine output,” says Best, which means you’ll be more likely to wake up dehydrated in the a.m. as a result. What’s more, you might also wake up in the middle of the night with a feeling of the urgency to pee, despite there being not much urine in terms of quantity to pee out.

To prevent this, try having a hydrating, low-sodium snack at night instead. Best recommends a small piece of fruit with high-protein source containing tryptophan and magnesium, both of which increase drowsiness to help you fall asleep faster. Examples include a small apple with unsalted peanut or almond butter, a slice of low-sodium, lean turkey breast on a slice of whole grain toast with guacamole, or Greek yogurt with walnuts and berries.

Keep in mind that caffeine and sugar can also lead to fluid loss, especially if consumed close to bedtime. “Try to cut off caffeine intake during the early afternoon and minimize added sugar intake to the American Heart Association recommendations of 24 grams—six teaspoons—per day for women and 36 grams—nine teaspoons—for men,” says Harris-Pincus.

5. Getting poor quality sleep—and mouth breathing

Another reason you might wake up dehydrated is from an increased loss of fluids and electrolytes as you sleep, which can be caused (and worsened) by poor quality sleep that results in mouth breathing. “Poor sleep quality may inhibit vasopressin production, a hormone that plays a vital role in water balance in the body. When this hormone is suppressed, the body isn't able to regulate fluid and electrolytes as well,” explains Best. “The body naturally loses fluids and electrolytes while we sleep, but mouth breathing at night causes more moisture in the mouth and nose to be lost gradually. As a result, you might have poor sleep quality that dehydrates you,” says Best.

Clearly, it's a vicious cycle. If you are prone to mouth breathing or wake up frequently, speak to a doctor to figure out what steps might be best for improving slumber and quality. You may also want to consider drinking water before bed to help keep dehydration overnight at bay.

6. Taking dehydrating medications at night

Some medications cause dehydration and water loss, which is often (and unfortunately) unavoidable. However, while some must be taken at night, others can be timed better and earlier in the day to prevent this issue. “For example, thiazide diuretics for hypertension, also known as water pills, can cause dehydration. They work by triggering the kidneys to release sodium as a way to increase urine production and water loss,” says Best. You don’t usually need to take them at night, she says, so chat with your doctor and discuss timing if this may be of concern.

Other medicines Best says can increase dehydration include OTC medications such as Excedrin for migraines, type 2 diabetes medications like Metformin, some chemotherapy drugs, as well as Apremilast for plaque psoriasis. Harris-Pincus adds that some chronic medications, most notably antidepressants, blood pressure medications, and laxatives, may also exacerbate dehydration symptoms. So if you must take them at night, be sure to hydrate more often and in larger quantities to maintain your hydration balance.

7. Heightened stress and anxiety, especially in the evening

There is a cycle that exists between dehydration and stress: They both cause the other, which can thus create an endless cycle. “Elevated stress causes heart rate to increase and heavy breathing, both of which cause increased water loss. You are also less likely to prioritize fluid intake and hydration when you are under stress,” says Best. One solution? Finding a way to decrease your stress levels before going to bed. Try to integrate relaxing techniques into your bedtime routine, like yoga, meditation, or journaling, and avoid the pre-bed doom scroll.

Another way to prevent the cycle is to focus on drinking an adequate amount of water during the day to stay well hydrated to counteract stress. “A good rule of thumb is that you should strive to drink about half your body weight in ounces of water,” says Best.

8. Sleeping for too long

Too little sleep isn’t good for you, but same goes for too many hours of shut eye—especially when it comes to dehydration. Why? Because the longer you sleep, the longer you go without replenishing your body's fluid stores.

“Sleeping for too many hours can contribute to dehydration because you are going for an extended period of time without drinking. I recommend not going over the recommended seven to nine hours per night, which is optimal,” says Harris-Pincus. You’ll feel Goldilocks-grade restored in the morning without feeling drowsy and thirsty.

9. Skipping out on hydrating skincare products before bed

The body performs many functions as you sleep to promote restoration that help you wake up feeling more refreshed. Such functions include muscle recovery and collagen production, both of which you can enhance further by applying overnight anti-aging products (such as face and body masks, lotions, and creams) before going to sleep. While this step won't impact your body's *actual* hydration levels, it will certainly make your skin feel less dry as well as protect your skin from the harmful effects of free-radical damage.

A few super hydrating foods to keep dehydration at bay:

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