Dehydration and Mental Health
Years ago, I remember having a patient with an eating disorder who stopped drinking fluids completely. Within a week, they were struggling with severe anxiety and depression. Upon my insistence, they started consuming water again and their mood rapidly improved. The episode was another reminder that our mental state is influenced by the physical condition of our body and that fluid intake can play a role.
Dehydration and Mood
Data from a number of studies have found correlations between mild dehydration and poor mood. A study in young adult men found that when mild dehydration was induced with a diuretic, cognitive function was decreased (Ganio 2011). In addition, tension, anxiety and fatigue all increased.
A study that induced dehydration through intravenous saline found that mood was significantly lower in women, but not significantly in men (Suh 2021). A study in men and women exposed to a hot environment were randomly assigned to receive water or not. Brain function was found to change for those that became dehydrated and anxiety increased (Young 2019). A study in young women had them exercise with standard hydration, without hydration and without hydration and a diuretic (Armstrong 2012). Dehydration was found to cause worsening mood, increased perceptions of difficulty in completing tasks and poor concentration.
A study on women who were dehydrated over 24 hours found reduced mood, decreased alertness, fatigue and confusion (Pross 2013). Of interest, the study found that you could identify when problems were starting to occur by how dark or concentrated the urine was.
Recommendations
While there are numerous recommendations for fluid intake, the simplest is to drink enough water to keep your urine from looking dark yellow. This could easily be 8 glasses or more of water per day based on your sex and your activity level, with men typically needing more water than women (see this part article for a discussion on average per day water losses).
Conclusion
Sometimes the simple aspects of our health can get overlooked. Hydration is often not emphasized for mental health, but it can have real weird consequences on both mood and cognitive performance. Drinking enough fluids so that you avoid your urine becoming overly concentrated is a simple way to maintain proper hydration.
