Are You Secretly Dehydrated? Why a 1% Drop Kills Your Focus and Mood

A lot of people rely on thirst alone and they assume if I need water my body will tell me, but the reality is thirst is actually a late signal. By the time you feel thirsty, your body's already playing catch up. Welcome to Office Hours. This is our dedicated one-on-one space to go deeper, get clearer, and explore what truly moves the needle for your health. I'm Dr.

Mark Hyman and each week we're going to pull back the curtain and share the insights, the research, the lessons that don't always make it into our conversations with guests. Because at the end of the day, you are the CEO of your own health, and for many of you, your family's health too. And you might not feel it all the time, but you have far more power and agency than you realize. I'm glad you're here. This episode is brought to you by Function Health, empowering you to live 100 healthy years with over 160 lab tests for just $365 a year, and use the code MARC 2026 to get $50 off your membership.

Most people think of hydration as something simple. Just drink more water. But what if Being even slightly dehydrated was affecting your brain, your focus, your memory, your mood, your energy. Because the truth is your brain is about 75% water, and even small changes in hydration will have a measurable impact on how it functions.

We already have this episode, so unlocking it is cheap and permanent: the full transcript (18 minutes, 3,411 words), segment and word-level timestamps, and .txt, .srt, .vtt and word-level JSON downloads, as many times as you like, forever.

No account needed, we create one from your checkout email. With credits it is 1 credit; packs start at 10 episodes for $5, and monthly plans are cheaper still.