Rehydrates After Sleeping

Your body naturally loses water every day through normal processes like peeing, sweating, and even exhaling, according to William W. Li, M.D., a physician. Some factors—like exercise, hot weather, or certain medications—can make you lose fluids even faster. But regardless of your specific water needs, one thing is for sure: You need to drink water each and every day.

"About 60 percent of the human body is composed of water, varying slightly based on age, gender, and hydration levels," says Casey Kelley, M.D., ABoIM.1 The body also requires water to lubricate joints, regulate body temperature, transport nutrients, and excrete waste via urine and sweating, just to name a few biological functions that rely heavily on proper hydration.

Since you can't sip while you snooze, your body is naturally in a dehydrated state in the morning, says Kelley. Thus, drinking H2O upon waking can be helpful, and you'll probably feel a bit thirsty when your alarm goes off anyway. "Drinking water when you wake up replenishes the lost liquid, including [the fluids] you might have lost during the night," Li confirms. This is especially true if you sleep with your mouth open or in a warm room, Li adds.

Boosts Energy Levels

According to Kelley, many people find that starting their day by drinking cold water helps wake them up. After all, dehydration (which, again, naturally occurs when you sleep) can make you tired and dizzy.2 Replenishing with a glass of water first thing in the morning can help prevent this by prompting the rehydration process, ensuring your tissues and organs get the fluids they need ASAP.

However, there are no hard "rules" for drinking water in the morning on an empty stomach. If you want to give this hydration hack a go, there are energy-boosting perks to approaching it in a certain way. For example, if you enjoy several morning cups of caffeinated coffee or tea in the morning, it can be helpful to drink water before (and also after) consuming it since a large amount of caffeine can be a natural diuretic, Kelley says.

Improves Mental Performance

Similarly, drinking water first thing in the morning can help maximize your mental acuity and productivity throughout the day. According to Kelley, dehydration is also linked to brain fog and headaches—so having a glass of water is a great way to boost mental performance first thing, Kelley shares. "Even mild dehydration is linked with some short-term memory loss and concentration, so if you want to stay on top of your game, drink that glass of water," Kelley says.

Stimulates the Metabolism

No matter the time of day, drinking water can get your metabolism going. Specifically, "cold water triggers your body to turn on a mechanism called cold-activated thermogenesis," says Li. "This means your body warms the water by turning on your metabolism, by as much as 30 percent, for about an hour."

But since cold-induced thermogenesis isn't time-specific, you don't necessarily need to do it before eating in the morning—though it's certainly an option if you want to kickstart your metabolism as soon as you wake up.

Promotes Digestion

According to Kelley, drinking water is critical for healthy digestion. For example, staying hydrated is helpful for easing constipation, a common side effect of dehydration.

"Warm water has the potential to break down the food you've eaten at a faster rate than cool water," Kelley says. Therefore, if you're prone to constipation, drinking [warm] water when you wake up can kick-start the rehydration process and get things moving ASAP.

Curbs Hunger

If you're not one for a big breakfast, if you don't have time to eat, or you find you're still hungry for junk after eating breakfast, sipping on water first in the morning on an empty stomach can help.

A 2018 study notes that drinking water throughout the morning can quell the sensation of hunger, potentially easing a grumbling stomach until you're able to eat (of course, if you need to eat, eat!).3 "It's very common to confuse the feeling of thirst with the feeling of hunger, so staying hydrated can reduce your urge to snack or overeat [when you aren't actually hungry]," Kelley says.

Alleviates Hangover Symptoms

Water is key when it comes to healing a hangover, Li says. This is because alcohol is dehydrating. When you wake up in the morning is likely when you'll feel the symptoms of the hangover the most—like a headache, nausea with or without vomiting, diarrhea, and sweating, for example. Getting your fluids by drinking water can feel revitalizing.

Enhances Skin

Drinking water at any time of day has tons of skin health benefits, from improving skin tone to preventing premature aging. When you drink it in the morning, in particular, you can help reduce any puffiness you may experience when you wake up. It can also help to prevent acne from any bacteria buildup on your pillowcases or if you fell asleep with makeup or skincare products on your face.