The amount of water in the body declines with aging, from about 80 percent in young adulthood to about 55 to 60 percent for people in their 80s, Dale said.
Temperature sensors in the brain become less sensitive as people age, so the body doesn't get the same signals to drink water in hot weather, and older people often don't feel thirsty even when they need to replenish, Dale said.
They also may not feel the typical symptoms of dehydration, such as headache or dizziness. Some complain of just feeling 'bad' and think they're getting sick, he said.
Conditions were ripe for those types of complaints Tuesday as a dense dome of hot air remained parked over much of the nation's midsection, raising temperatures into the mid- to upper-90s from the Texas Gulf Coast to the Rockies and the northern Plains. Tropical-level humidity raised the heat index in many places to nearly 120 degrees."
