Dehydration Adversely Affects Mood & Productivity

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Dehydration Adversely Affects Mood & Productivity

Well established in prior posts is the fact that dehydration adversely affects cognitive and mental performance; all factors that in turn affect productivity, which is why it’s crucial to remain properly hydrated during the work day. But dehydration is also known to affect mood, another factor which can hinder performance, and one which is more closely examined in a research paper entitled Influence of progressive fluid restriction on mood and physiological markers of dehydration in women.

Published in 2012 and available in full here, the study can be split into hypothesis, methodology and results.


The aim of the study was to evaluate the effects of dehydration – achieved via fluid restriction over a 24-hour period – on certain mood and physiological criterion. Earlier studies had focused mostly on athletes where severe dehydration was achieved under extreme conditions; as a result, not much information was available on the effects of mild dehydration experienced in normal circumstances.


The subjects were 20 healthy women with the average age of 25 years. They smoked less than five cigarettes per day, were only moderate drinkers of alcohol and caffeine-containing drinks, and were all oral contraceptive users, participating in the study outside of their menstruation period. During the trial they were asked to refrain from intensive physical exercise, smoking, and any alcohol or caffeine consumption.

The women participated in two test sessions.

In one session, total fluid deprivation (FD) was required – just prior to 7pm on day 0, the women drank 2 x 250 ml of water, thereafter, from 7pm until 6pm the following day the women were not allowed to drink anything at all.  After the 6pm cut-off they were free to drink as they wished.

In the other session, water consumption was standardised – 500 ml at meal times and 250 ml at various snack and hydration points. The total intake for the trial period was 2 litres.

In both sessions they were required to sleep 8 hours per night and their activities, along with the relevant test batteries were kept the same.


To recap: the aim of the study was to examine the effect of dehydration on mood and other physiological changes in 20 healthy young women. In terms of their vital signs, with the exception of heart rate, there was no difference between the two test sessions.

But when they were dehydrated, during the fluid deprived test session, their heart rate value was higher at all time intervals throughout the test session.

With regards to mood, the most significant effects during the fluid deprived test session were centred around sleep/wake parameters.

Dehydration led to increased sleepiness and fatigue, lower levels of vigour/activity and alertness and increased confusion.

Interesting to note was that when subjects were allowed ad libitum water intake at the end of the FD test session, it helped to reverse dehydration-induced decreases in happiness and alertness, and dehydration-induced increases in confusion and bewilderment.

Proof yet again that the simple act of drinking water should never be underestimated – the power of hydration not only ensures optimal health and increased productivity, but it also helps to promote a positive and vital mind-set.

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