Last Updated May 5, 2009 7:14 AM EDT
As it happens, even quite mild dehydration can cause problems such as headaches and constipation.
But, in my experience, perhaps the most common and under-recognised manifestations of dehydration are fatigue and lethargy -- both physical and mental.
In other words, if individuals want to take one simple step towards keeping their energy levels (and therefore their effectiveness and efficiency) buoyed up throughout the day, then my advice is simply to drink more water.
However, knowing the benefits of drinking water and actually drinking it are two different things. Even when we know the benefits it may bring, we won't always get a decent daily quota. One usually effective tactic that helps here is to keep water by us.
Individuals who keep water on their desk and ensure it's available in meetings usually find that they drink plenty of it quite automatically. On the other hand, going to the water cooler at the end of the corridor can be a stretch too far for some of us.
There is a lot spoken about how much we should drink, with eight glasses of water each day being the oft-quoted ideal amount. In reality, though, our needs for water are highly individual and are affected by factors such as body size, sweating, activity and exercise levels, temperature and humidity.
One good 'individualised' gauge of the state of our hydration, though, is the colour of our urine. The aim is to keep urine colour pale yellow (and sometimes even colourless) throughout the course of the day. If, at any point, you notice your urine has strayed into darker tones, and particularly if it has become noticeably odourous, then the chances you are suffering from a spot of dehydration.
I suggest using this as a signal to up your water intake. My experience is that this usually leads to a lift in energy levels and productivity in half an hour or so.