Most of us know it’s important to drink more when it’s hot outside, especially when we’ve been physically active. Without replacing the fluids we lose through sweating, we can start to show signs of heat-related illness, such as lightheadedness and muscle cramping. Dehydration also strains the heart and kidneys. This advice may seem like a “no brainer” to some, but it’s not always that simple for older adults.

Ongoing research from the Human Heat Stress Project in Montreal, presented at the 2024 Integrative Physiology of Exercise meeting, showed age differences in how much people drink—and when they start drinking—in a hot environment. The researchers looked at three age groups, with the oldest being people between the ages of 66 and 88. The volunteers stayed in a hot, humid room (around 100 degrees F) for four hours and did 10 minutes of light exercise every hour.

The study volunteers could drink as much water as they wanted throughout the trial and were asked to rate how thirsty they were each time before they took a drink. The youngest age group (ages 18 to 39) started drinking water after an average of just 14 minutes in the hot room. The oldest group didn’t drink until around 38 minutes, reported feeling less thirsty compared to the younger people, and did not drink enough to replace their sweat losses.

Not feeling thirsty as we age could be because of changes in our baroreceptors, which monitor blood pressure and blood volume. As we get older, baroreceptors become less sensitive to decreases in blood volume. However, not drinking as much as we should when we’re older could also be linked to changes in kidney function and our concerns about frequent trips to the bathroom, explained Thomas Deshayes, PhD, first author of the study

Keeping older adults hydrated and healthy, especially in the heat, is a little more complicated than just reminding them to drink more. Deshayes pointed out that “not everyone, irrespective of age, hydrates in the same way” and that communication is key.

Talking to people about their activities and hydration habits can make it easier to get a clearer picture of how someone replenishes their fluid losses. It’s also important to talk to the low drinkers to better understand their reasons and explore effective solutions to encourage greater fluid intake, Deshayes said.

During periods of heat, he also recommended adjusting activity type, location and intensity. This could include adding swimming as a form of exercise, taking more breaks and exercising in shorter bursts.

With summer temperatures hitting all-time highs and warmer days year-round, it’s clear the problem of hydration is not going away. Let’s remember to talk to each other to eliminate some of the worries and roadblocks to good health.