Changes in daily water intake impact mood of high and low drinkers

Abstract

PurposeThe effect of dehydration on cognition has been examined in fluid deprivation studies. However, such study conditions are far from real life conditions. This inpatient crossover trial evaluated the effect of mild changes in water intake on subjective cognitive performance (i.e. mood) in 22 high volume (HIGH; 2–4L/d; 25 ± 1 y) and 30 low volume drinkers (LOW; <1.2L/d; 25 ± 3 y).MethodDuring days 1 and 2 HIGH consumed 2.5L of water/day and LOW 1L/day. On Days 3 through 5, HIGH restricted water intake to 1L/d and LOW increased to 2.5L/d. Several mood scales (Bond & Lader VAS, Profile of mood states, Karolinska Sleepiness Scale, Thirst & Emotional VAS) were administered at different time points. An ANOVA model including treatment, time point and treatment × time as fixed effects on mean values (i.e.; baseline data vs mean of 3 intervention days) for each mood scale was performed.ResultsIn LOW increased water consumption resulted in a significant decrease in fatigue (p<0.001), confusion (p=0.05) and thirst (p<0.001) and a trend to lower sleepiness (p=0.07) compared to baseline. In HIGH the restricted water intake lead to a significant increase in thirst (p<0.001) and a decrease in contentedness (p<0.05), calmness (p<0.01), positive emotions (p<0.05) and vigor (p<0.001).ConclusionIncreasing water intake has a beneficial mood effect, especially on sleep/wake feelings, whereas restricting water intake can deteriorate mood. Even though the results were observed in young adults, they can still be of importance to the healthy aging population. The link between water increase and decrease in confusion is also of interest for diagnosis and treatment of delirium.