Having coffee in the morning on an empty stomach and in a dehydrated state does not help since it invokes a fight or flight response, which is not favorable in the long run. Most of us are tired even after waking up. Something like mild dehydration can give rise to tiredness, moodiness, anxiety and prickliness. Even a 2% loss of water can lessen mental performance and cause memory loss. The fact that 78% of Americans are chronically dehydrated further makes a statement about our poor beginning of the day