Drinking water before brushing after waking up: Why more people do it and its benefits

While you sleep, your body keeps losing water through breathing and sweating, anywhere between 400 to 600 ml overnight. You wake up mildly dehydrated every day without realising it. Replenishing that loss with a glass of water first thing is one of the easiest ways to start your system off right.

Your brain is roughly 75 percent water. Even mild dehydration slows it down. A peer reviewed study published in PLOS ONE found that dehydration measurably affects attention, working memory, and mood. Rehydrating first thing in the morning helps your brain function closer to its actual capacity before your day even begins.

Drinking water on an empty stomach gives your metabolism an early push. A study published in the Journal of Clinical Endocrinology and Metabolism found that drinking 500 ml of water increased metabolic rate by 30 percent, with the effect starting within 10 minutes. A morning glass on an empty stomach makes the most of this window.

Water first thing in the morning stimulates the colon and gets your digestive system moving. A study published in BMC Public Health confirmed that adequate fluid intake is directly linked to reduced constipation and better bowel regularity. A morning glass before food helps set that rhythm for the rest of the day.

Your kidneys filter waste all night. Morning water helps flush that accumulated waste out through urine before anything else enters your system. The National Kidney Foundation notes that dehydration makes it harder for kidneys to function well and increases the risk of kidney stones over time. A simple morning glass keeps them supported.

Overnight fluid loss also affects your skin from the inside. Rehydrating early helps restore elasticity and flush out toxins that can cause dullness or breakouts. A study in the International Journal of Cosmetic Science found that regular increased water intake improved skin density and thickness, particularly in people who were not drinking enough to begin with.

This is the question most people ask. In Ayurveda and the Japanese water therapy tradition, drinking before brushing is intentional, as saliva produced overnight has beneficial enzymes. While the science on this specific point is limited, drinking water before brushing poses no health risk for healthy adults and does not meaningfully affect dental health according to most dentists.(Disclaimer: This story is for educational purposes alone and should not be considered as professional medical advice and does not substitute any medical advice.)