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NEW YORK (Reuters Health) - Senior citizens reported feeling less tired than younger people, including teenagers, in a new U.S. study.
To the researchers' surprise, 15- to 24-year-olds - the youngest people in their study - said they felt the most fatigued of all during daily activities. The difference between the two age groups was almost one full point on a scale of 0 to 6, with 6 representing "very tired."
"It's a big effect," Laura Kudrna told Reuters Health. She and her colleague, Paul Dolan, conducted the study at the London School of Economics and Political Science.
The link between increasing age and decreasing fatigue held steady when they factored in how much people slept, how many children they had, whether they were employed and their general health.
Additionally, the researchers found people who were more educated and healthier tended to be less tired. Women reported feeling more tired than men. And feelings of fatigue increased with each additional child in the family.
The study of nearly 13,000 Americans is one of very few to investigate tiredness on a large scale, said Kudrna. It was published in the Journals of Gerontology Series B.
"The evidence on this so far is quite mixed, and most studies have either been done in clinical settings or in Europe," she said.
"Saying that you are tired is a status symbol in American society," Kudrna said. She added that people tend to overestimate how tired they felt when asked about large swaths of time.
In an attempt to get around that, Kudrna and Dolan pulled data from the most recent American Time Use Survey.
In 2010, U.S. Census Bureau researchers asked a group of Americans between ages 15 and 85 to complete an "activity diary" on certain days. A bureau researcher would then randomly choose three activities and call the participant, asking how tired the person felt on a scale of 0 to 6 during specific events, like eating dinner or talking to friends.
Average fatigue scores fell from 2.5 among the youngest participants to about 1.8 for the oldest.
One possible explanation for the finding could be related to "how older people are able to use their time and do what they want to do when they want to do it," Kudrna said.
Also, because older people tend not to use social media, they "may not have their attention drained the way that younger people might," she added.
"This is a provocative paper, which raises much thought about what it means to be tired in old age," Donald Bliwise, from Emory University School of Medicine in Atlanta, said.
Bliwise directs the Program in Sleep, Aging and Chronobiology at Emory and was not involved in the current research.
The study is "challenging many preconceived perceptions of fatigue and tiredness in old age," he told Reuters Health. "But it must be taken with a bit of skepticism at this point."
People can be poor judges of how much sleep they actually get and this is when a sleep lab comes in handy, Bliwise said. And information from doctors about participants' general health would have been helpful, he added.
"Older people feel better in day-to-day life than younger people, and that is a widely replicated pattern in research," Laura Carstensen, director of Stanford University's Center on Longevity in California, said.
Carstensen was not part of the current study.
Past studies have shown negative emotions tend to decline with age. "That same effect is probably what is at the root of this subjective assessment," she told Reuters Health.
"The findings may reflect something other than what people think of as tiredness, which is usually associated with muscle strength and soreness, as well as cardiovascular ability," Carstensen said.
The researchers agreed that tiredness and fatigue are complicated concepts to study.
"Maybe there are some underlying health factors at play here," Kudrna said. "The more we know about how the U.S. population feels going about their daily activities, the better."
SOURCE: bit.ly/1cyGUra Journals of Gerontology Series B, online November 22, 2013.