After the latest research the answer is no. It doesnt dehydrate. Asking around a opinion on this matter, people strongly believe that coffee dehydrates. The traditional idea that coffee is a diuretic sicks around. The feeling of urination after soon after we have a cup determines all of us to believe that coffee is a necessary evil. It gives energy with the loss of water. This is  a personal experience that is difficult to chalenge. But what if I told you that the water that’s coming out is “bulk water”, unusable by the cells and your cup of coffee is replacing it thus hydrating you.

A research recently made shows no changes in water content of our tissue or bood plasma in a trial comparing water consumption against coffee. But this is the tip of the iceberg. Here is the coffee myth-busting. It keeps the water in but we also know it raises the cortisol level. Cortisol is the hormone that is waking us up in the morning. It starts to go up around 30 minutes before we wake up. It’s suppose to be stimulated by bright light in the morning. Light that we are missing as we get around the house after being woken up by an alarm clock. We spend in the morning at list the first hour under artificial light. Light that is missing the morning sun spectrum. This is affecting our circadian cycle. When this cycle is affected the AM cortisol level is reversed with the PM one. We suppose to have it low in the evening and high in the morning. Artificial light in the evening is rising it up making us quite active. Pretty good to check that social media and feel upbeat to do a couple of extra things around the house. This is called an upside down cortisol curve. This is when coffee gives us a hand in the morning. It replaces the sunrise action over the cortisol levels. It hydrates and helps putting more water in between the nerves and glial cells in the brain. The cortisol hormone initiates the wake-up process by inserting this water that is provided by the coffee. We do feel better, sharper and ready for a brand new day. In our modern world we have found a good friend in coffee a nice trick to solve an issue. Issue created by our “light smog” in the evening. It perpetuates on daily basis and it goes unnoticed until more issues are piling up.

The takeaway

A poor hormonal panel starts with upside down cortisol levels. If you cannot make it without coffee in the morning now you know why. Its good to bring this up to your physician and get tested on saliva cortisol level. This  has at list two up to four tests to take home, for different hours of the day. It will show your daily cortisol curve. Even coffee lovers are trying to sync the time for with  the cortisol curve. Why is this important? This hormone steals from the other steroidian hormones like estrogen, testosterone and progesterone. It can up regulate your thyroid production of T4 initially and raise cholesterol. These two are needed for hormonal production. As we can see needing coffee in the morning can hide ugly things. Keep an eye open for these sorts of needs that are just another demand created by our social life interacting with human biology.

More to read:

Cortisol Response

Coffee and Tea Lowers Risk of Brain Cancer