Written By Damien Cox – Accredited Practicing Dietitian

Someone’s Mood is affected by multiple different factors throughout their daily living. Stress, sleep, work, other people, needing to eat are all factors that can affect someone’s mood [1]. But can hydration and the amount of fluid we consumed in a day play a role as well? People often say if we don’t drink enough fluid we may get a headache, tired and light-headed. This can clearly impact on someone’s mood and wellbeing however how much truth is there really to this statement? Does our hydration really affect how we feel, can we fix a headache by just drinking some water? Let’s find out.


There is growing evidence suggesting that the food and drinks we consume affect not only our physical performance but mental capacity as well [2]. In some people mild levels of dehydration can disrupt mood and cognitive function [3]. This impact of is mainly shown in the very young, very old, those in hot climates and those engaging in physical exercise [3]. There is however conflicting evidence that show no correlation between cognitive impairment and hydration [4-5]. These inconsistencies make it difficult to draw to complete conclusions on how hydration can affect the broad population’s cognitive function.


Although the evidence may not be as clear cut on how hydration affects each persons cognitive function. The evidence is very clear when effecting our mood. In multiple studies the evidence shows that in levels of dehydration degraded mood, lower concentration levels and headache symptoms are all present [3,6-8]. In one study in healthy young women Armstrong et al found that fatigue, vigour, fatigue, and mood were negatively affected in only a 1.36% drop in hydration status! [7].

 So, can it be easily fixed? Is it as easy as having a glass of water and the headache is gone?

In studies that compared dehydration scores to scores after rehydrating the evidence is clear. Rehydrating improves fatigue, mood, short term memory and attention [3,9-10]. However, this is dependent on the level of dehydration someone is experiencing plus the amount of fluid that is needed to drink to restore hydration status.

Inconclusion the research is unclear about how hydration level impacts cognitive function. However we do know it impacts mood and our fatigue levels throughout the day. So remember your water bottle and don’t forget to keep it filled up the next time you’re having a stressful day.

Fun Fact!

In a pilot trial study in particular study Spigt et al examined the effects of increased water intake in people who suffered from headache or headache like symptoms (migraine and tension headaches) [11].  When headache symptoms raised one group had a placebo medication and one group was told to drink 1.5L of water per day for the 12 weeks duration. The study showed that the number of headaches by both groups did not differ however the intensity and total number of hours was less in the group that drank extra water. Although the results are positive to increased water consumption and headache management the study sample size was small (n=18) and Spigt et al concluded more evidence needs to be conducted to make final conclusions.

Reference List:

  1. https://www.betterhealth.vic.gov.au/health/healthyliving/monitoring-your-mood
  2. https://doi.org/10.1038/nrn2421
  3. doi: 1111/j.1753-4887.2010.00304.x
  4. doi: 10.1213/ane.0b013e3181615247
  5. https://doi.org/10.1016/j.physbeh.2007.11.028
  1. 10.1007/s00421-012-2506-6
  2. DOI: 10.3945/jn.111.142000
  1. doi: 10.1152/ajpregu.00501.2004
  2. https://doi.org/10.3390/ijerph16111891
  3. doi: 10.1371/journal.pone.0094754
  4. doi: 10.1111/j.1468-1331.2005.01081.x.