This Is The First Thing A Neuroscientist Checks When Patients Have Brain Fog 

Got brain fog? You know, that feeling of mental fatigue that clouds your thoughts, keeps you from concentrating, and just generally makes you feel crummy? While it's not technically a medical diagnosis, it's pretty common—and it can happen for a number of reasons. If you've been feeling blah for some time, you may seek out an expert who can help you navigate those symptoms. 

Your brain is literally made up of water (75% to be exact!), so it needs fluids in order to work properly. "[Water is] going to help keep your blood pressure normalized; it's going to help flush out [waste] from your cells; it keeps your cells metabolically active and healthy," Willeumier adds, all of which are important functions for brain health. 

Not to mention, water is crucial for memory and mental clarity: Willeumier explains that even if you have a 1 to 2% drop in hydration, you can start to have symptoms associated with brain fog1, like fatigue, headache, and poor concentration. Another study shows that when a group of young, healthy women restricted their water intake to no more than 6 ounces in one day, they performed worse on cognitive tests that required visual and working memory2; after they drank enough water and repeated the tests, their executive function went back to baseline. 

A perfect segue to the next question: How much water should you be drinking? 

The answer is that it differs for everyone depending on your environment, activity level, and diet (example: Keto folks or those who simply eat more meat may need to drink more water to match the dehydrating diet), but experts generally recommend you drink half your bodyweight in ounces of water. 

Fill up your water bottle and get sipping! If you need more help reaching your personal hydration benchmark, Willeumier says you can opt for hydrating foods as well to meet the threshold. "You can get 20% of that water from hydrating fruits, vegetables, or green juices," she says.