I used to heavily underestimate the importance of drinking water to stay well hydrated, especially when I moved to Thailand. 

The high temperatures here, combined with humidity usually in the range of 70% or higher, made me dehydrate very quickly. Because the air is already saturated with water, sweat doesn't evaporate to successfully cool you down, and thus you perspire continuously.

Now it wasn't that I that I didn't drink any fluids, but rather that I wasn't drinking enough water. Because of the low cost of carbonated drinks, coffee, and flavoured teas I didn't see the need to drink water as I was already taking in fluids. How very wrong I was! After about 2 weeks or so I started observing some symptoms. I felt sleepy and had a general lack of energy, I noticed irregularities in breathing, I would get dizzy, and had urine of dark colour.

I took the time to look up the symptoms, and it struck me immediately! I couldn't believe how blind I was, when I should have known better. Needless to say, I stopped my bad habits and I now drink at least two litres of water per day. All of my previous symptoms were gone by the second day of staying properly hydrated with good old-fashioned water.

I hope this helps answer your question. Stay healthy and hydrated!!