Guy Reams (00:01.164)
This is day 126, the secret to thinking better. That secret is water. You recently I made a simple change. I started drinking more water. No supplements, no new productivity system, no dramatic lifestyle overhaul, just consistent hydration throughout the day. What surprised me was how my mind responded. My thinking felt faster. Words came more easily. Decisions felt clearer.
The usual afternoon mental fatigue almost disappeared. My ability to process complex ideas seemed to come back. At first, I wondered if this was a placebo or was something more foundational happening? Well, hydration does have a direct and measurable impact on cognitive function. I think that's pretty much a scientific fact. Your brain is about 75 % water.
Water is not optional for brain performance. It is structurally and functionally essential. Even mild dehydration, as little as to 1 to 2 % loss of body water, impairs your attention, your memory, your mood. As dehydration progresses, cognitive performance declines. This is not motivational advice. It is psychological reality. When you are dehydrated, blood volume decreases.
That means less oxygen and fewer nutrients reach the brain. Metabolic efficiency drops. Neuro transmitter production slows, which can shift your mood, slow processing, and increase your irritability and anxiety. Brain tissue can temporarily shrink even, triggering headaches and reducing mental efficiency. Energy production declines because cellular metabolism requires water. Lower
ATP means lower mental energy. Even small levels of dehydration matter far more than you think. At 1 to 2 % dehydration, attention span drops. Short-term memory immediately suffers. Reaction times slow. Tasks feel harder than they actually are. And mood shifts towards irritability, anxiety, and fatigue. Most people operate here daily without even realizing.
Guy Reams (02:19.342)
At 3 to 4%, work in memory declines significantly. Executive function, planning, and decision-making weaken. Psychomotor performance drops. Visual and spatial processing becomes more difficult. Beyond 5%, confusion and disorientation can set in. Severe cognitive impairment falls. And, of course, the risk of delirium and hallucinations rise.
The good news is very simple. Cognitive performance often rebounds within 15 to 30 minutes after you rehydrate. Even mild deficits can reverse very quickly. Severe dehydration may leave some residual effects for a few hours, but recovery does begin rather fast. This is not a long-term rebuild. It is a near immediate correction. We chase complexity while neglecting the most
basic requirement for clear thinking. We chase productivity hacks, we buy supplements, we optimize software, we tweak workflows, yet we neglect the most basic psychological requirement for thinking clearly. Sometimes the biggest lever is not that complicated. It's foundational. I think back to that small decision I made to drink more water recently. Nothing dramatic, nothing impressive, just consistent hydration.