September 26, 2025
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People who consume fewer than six glasses of water a day have a significantly harder time managing stress than people who hydrate more, new research shows.
Feeling stressed? Drinking more water might help, a new study suggests.
Research published in the Journal of Applied Physiology found that people who consumed fewer than six glasses of water a day had a significantly harder time managing stress than people who hydrated more. More specifically, people who drank less than 1.5 liters (about 6 to 8 cups) of fluid a day had cortisol levels that were 50% higher when under stress.
"The finding suggests that chronic mild dehydration may amplify stress responses in ways we're only beginning to understand," the researchers wrote in The Conversation.
Cortisol is a hormone that helps regulate blood pressure, reduce inflammation and control the body's sleep-wake cycle. When under stress, the adrenal gland produces more cortisol, and higher cortisol levels can lead to health complications, such as high blood pressure and a weakened immune system, according to the Cleveland Clinic.
The study divided healthy adults into two groups, one that drank less than 1.5 liters of water or hot drinks a day and another that consumed more than 2 liters a day. Participants from each group underwent 5-minute mock interviews and performed 5-minute mental arithmetic tests.
Both groups reported feeling anxious in these situations and had increased heart rates. But cortisol levels measured in the saliva of the people who drank less were much higher than in people who drank more fluids.
"If you know you have a looming deadline or a speech to make, keeping a water bottle close could be a good habit with potential benefits for your long-term health," the study's lead author, Neil Walsh, said in a news release.
Previous research has found associations between poor hydration and negative mental health outcomes. A 2024 study found that Korean adolescents who drank less water had a higher risk of self-reported depression and suicidal ideation or intent. Another study from 2018 found that Iranian adults with lower water consumption reported higher levels of depression.
The recent study suggests that hydrating well can help mitigate stress and anxiety levels, along exercise, a healthy diet and adequate amounts of sleep, the researchers said.
Many healthy people can stay adequately hydrated drinking when thirsty and may only need about 4 to 6 cups of water a day – with variations based on activity level, daily temperature and other factors, according to Harvard Health.
But recommendations from different organizations vary.
The U.S. National Academies of Sciences, Engineering, and Medicine advises women get about 11 1/2 cups of fluid and men about 15 1/2 cups of fluid a day – including water, other beverages and food.
The National Academy of Medicine recommends that healthy women drink about 9 cups of water and men about 13 cups of water a day – with a cup equalling 8 ounces.
