Does hydration affect thinking and mood?

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1. 1

   Healthcare workers hydration status and performance: a scoping review.

   Frontiers in health services (Da'ar et al.)Published Aug 25, 2026Checked Oct 3, 2026

   “The search was carried out between March 2023 through September 2023.ResultThe scoping search identified 17,799 records, of which 15 met the inclusion and exclusion criteria, and were fully reviewed (N = 15). The result shows that dehydration affects healthcare workers significantly, with 60% reporting reduced physical performance when dehydrated during shifts. Nearly half (53%) of studies document declines in cognitive pFerformance and mood. This mental strain increased with longer shift lengths, particularly among nurses on 12-h shifts and medical residents working more than 24 h.ConclusionThere is a lack of adequate studies on healthcare workers' hydration health and its impact on performance, cognition, and mental well-being. Future research should be conducted in both cross-sectional and experimental methodologies, incorporating quantifiable measures to evaluate hydration and interventions. Countries with hot climate, such as, Saudi Arabia, should lead this research agenda, given that high temperatures could amplify the effects of inadequate hydration.”

2. 2

   Multimodal MRI local metrics and cognitive performance following water intake in 12-h water-restricted adults: a randomized controlled trial.

   Frontiers in nutrition (Zhang et al.)Published May 15, 2026Checked Oct 3, 2026

   “all groups, and higher ReHo signals in right orbitofrontal gyrus vs. low-intake/control groups. This group also had lower cerebrospinal fluid density in limbic lobe vs. medium-intake/control groups. The medium-intake group demonstrated higher gray matter VBM values in hippocampus, superior frontal gyrus, and putamen vs. high-/low-intake groups. No significant between-group cognitive differences emerged. However, within-group comparisons revealed improved symbol search across all intake groups, increased mental arithmetic span for high-/medium-intake groups, and enhanced mental arithmetic scores specifically in the high-intake group.ConclusionsThis study preliminarily demonstrates that water intake following 12-h water restriction may improve hydration status to some extent in young adults, with observed changes in localized multimodal MRI metrics in specific brain regions and in select cognitive test scores compared with pre-intervention values; however, the correlations among these changes require further analytical validation.Clinical trial registrationhttps://www.chictr.org.cn/showproj.html?proj=19279, identifier: ChiCTR-IOR-17011568.”

3. 3

   Association Between Hydration Status, Nutrition, and Cognitive Performance in School-Age Children in Kumasi, Ghana: A Cross-Sectional Study.

   Health science reports (Commey et al.)Published May 4, 2026Checked Oct 3, 2026

   “Cognitive performance was measured using Raven's Colored Progressive Matrices. Linear and binary logistic regressions examined associations between hydration status, nutritional indicators and cognitive performance.ResultsThe sample comprised 37.5% males and 62.5% females. Mean Z-scores for BAZ (-0.13) and HAZ (-0.11) indicated generally normal growth, though 17.5% of children were overweight/obese and 8.5% were stunted. Notably, 89% of participants were dehydrated, while 70% passed the cognitive test. Multilinear regression revealed an inverse association between BAZ and continuous USG (β = -0.273, p = 0.005) and a positive association between HAZ and USG (β = 0.189, p = 0.01). In binary logistic regression, only HAZ remained significantly associated with categorized hydration status (OR = 0.58, 95% CI: 0.36-0.93, p = 0.02). No direct associations were found between hydration status and cognitive performance.ConclusionDehydration was highly prevalent among school-age children in Kumasi and was significantly associated with height-for-age. These findings emphasize the need for integrated nutrition and hydration assessments in pediatric health programs.”

4. 4

   A randomized trial on thirst satiation during exercise in the heat: Effects on thermal strain, perceived concentration, and executive function.

   Nutrition and health (Ky et al.)Published Sep 10, 2026Checked Oct 4, 2026

   “Thirst was measured every 5 min with visual analog scales. The Environmental Symptoms Questionnaire (ESQ), Profile of Mood States (POMS), a modified flanker task, body mass, and urine specific gravity (USG) were recorded before and the end of each trial.SummaryThere were no significant differences in body mass loss and USG (p ≥ 0.14), demonstrating similar hydration states. Thirst was higher in HT compared to LT after 15 min and throughout the 90 min and 12 km time trial (p = 0.006). Participants reported feeling performance decrements (mean ± SD; HT: 3.7 ± 0.2, LT: 3.1 ± 0.3, p = 0.012), difficulty concentrating (HT: 1.8 ± 0.2, LT: 1.4 ± 0.1, p = 0.032), and an overall heightened subjective thermal strain (total ESQ, HT: 27.3 ± 1.1, LT: 24.8 ± 1.0, p p > 0.05). Thirst may not affect executive function performance, though it may increase subjective thermal strain during exercise in the heat. This study suggests that strategies for mitigating thirst are as important as maintaining hydration status to maintain concentration and subjective thermal strain.”

5. 5

   The Role of Hydration in Children and Adolescents-A Theoretical Framework for Reviewing Recommendations, Models, and Empirical Studies.

   Nutrients (Zborowski & Skotnicka)Published Aug 31, 2025Checked Oct 3, 2026

   “Hydration affects not only the health of young people, but also their cognitive abilities, concentration, mood, and general well-being. Despite clear recommendations from institutions such as EFSA and IOM regarding daily fluid intake, numerous studies indicate that a significant proportion of young people do not achieve the recommended level of hydration. The school environment is particularly worrying, as young people spend a significant part of their day there, and the availability of water, health knowledge, and social conditions may contribute to dehydration or promote unhealthy choices (e.g., sweetened drinks). The aim of this article is to review the current state of knowledge on the importance of hydration in school-age adolescents. The physiological basis of hydration, the impact of insufficient fluid intake on the functioning of the young body, current guidelines, as well as the results of selected epidemiological studies and obstacles to ensuring optimal hydration in the school environment are discussed.”

6. 6

   Dehydration (Wikipedia)

   WikipediaPublished Sep 29, 2026Checked Oct 3, 2026

   “In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild dehydration can also be caused by immersion diuresis, which may increase risk of decompression sickness in divers. Most people can tolerate a 3–4% decrease in total body water without difficulty or adverse health effects. A 5–8% decrease can cause fatigue and dizziness. Loss of over 10% of total body water can cause physical and mental deterioration, accompanied by severe thirst. Death occurs with a 15 to 25% loss of body water. Mild dehydration usually resolves with oral rehydration, but severe cases may need intravenous fluids. Dehydration can cause hypernatremia (high levels of sodium ions in the blood). This is distinct from hypovolemia (loss of blood volume, particularly blood plasma). Chronic dehydration can cause kidney stones as well as the development of chronic kidney disease.”