Progression of human subjective perceptions during euhydration, mild dehydration, and drinking

Area of Science:

• Physiology
• Psychology
• Behavioral Science

Background:

• Thirst is a primary motivator for water consumption, crucial for health and cognitive function.
• Limited understanding exists regarding coexisting perceptions and moods influencing body water homeostasis beyond thirst.
• Investigating these subjective states is vital for a comprehensive view of hydration regulation.

Purpose of the Study:

• To observe subjective perceptions, somatic sensations, and moods during controlled changes in hydration status.
• To delineate the evolution and time course of these perceptions during dehydration and rehydration.
• To understand how these factors contribute to drinking behavior and water balance.

Main Methods:

• 18 healthy young men participated in a controlled hydration study.
• Subjective ratings of 17 perceptions were collected hourly using visual analog scales (VAS) over 24-hour periods.
• Hydration states included euhydration, water restriction (WR), and a 30-minute rehydration session (R30).

Main Results:

• Significant changes in perceptions were observed across hydration states.
• During WR, thirst, mouth dryness, and desire for water intensified progressively after approximately 4 hours (2.12% body mass loss).
• Post-rehydration (R30), participants reported a reversal of dehydration symptoms, alongside increased satisfaction, stomach fullness, and cooler thermal sensations.

Conclusions:

• This study identified previously unreported perceptions and their temporal dynamics related to hydration.
• Aversive moods and specific sensations were found to motivate drinking behavior during water restriction.
• The findings suggest that these evolved perceptions play a role in both initiating drinking and preventing overconsumption.