"When elderly people complain they're tired, most doctors say, 'Yeah, well, you're old.' They tell their patients that feeling listless is an expected part of aging, but there are reasons people are tired, and they need to be investigated. For clinicians, the message from our study is that a lack of energy is widespread in the elderly, but it's not normal," senior author Dr. Mathew Maurer, associate professor of clinical medicine at Columbia University Medical Center, said in a news release.

The study of more than 2,100 New York City residents, ages 65 to 104, found that almost one in five reported so little energy, they spent most of the day sitting on the sofa. In this study, participants were classified as anergic if they said they sat around due to lack of energy and agreed with two of the six following statements:

• "I recently have not had enough energy;" "I felt slowed physically in the past month;"
• "I did less than usual in the past month;"
• "My slowness is worse in the morning;"
• "I wake up feeling tired;"
• "I nap more than two hours a day."

The researchers found that the 18 percent of study participants classified as anergic reported more arthritis, sleep disorders, cardiovascular symptoms and other health issues . Researchers also reported twice as many overnight hospitalizations, emergency department visits and home care services. In addition, anergia was associated with a 60 percent greater rate of death in the six years after participants were surveyed, the study said. Heart disease, kidney dysfunction, arthritis, lung disease, anemia, and depression are among the many conditions that may cause anergia.

"I believe anergia is the universal language by which the elderly talk about their health problems," Maurer said. "Instead of noting symptoms of pain or a depressed mood, many older adults feel more comfortable telling their physicians that they are tired. As health care providers, we need to start learning how to further identify the underlying causes of this lack of vigor and address them."

Maurer and his colleagues wrote that anergia needs to be regarded as a geriatric condition similar to common age-related syndromes such as memory impairment and increased risk of falling.

In an extension of this initial study, the Columbia researchers found that anergia occurred in 39 percent of older adults with heart failure. They also found demonstrable differences in physical activity levels and circadian rhythm between those with anergia and those without anergia. Circadian rhythm sleep disorders are a family of sleep disorders affecting, among other things, the timing of sleep. People with circadian rhythm sleep disorders are unable to sleep and wake at the times required for normal work, school, and social needs. They are generally able to get enough sleep if allowed to sleep and wake at the times dictated by their body clocks. Unless they have another sleep disorder, their sleep is of normal quality.

"As our population ages, it has become paramount to the health of our nation to accurately describe the health problems associated with age," Dr. Linda P. Fried, dean of the Mailman School of Public Health at Columbia University Medical Center, said in the medical center news release.

"A central feature of the frailty phenotype that we described years ago is self-reported exhaustion. The current study suggests that this concern expressed by patients or their caregivers is important and may be a very useful question in identifying older adults susceptible to functional decline and poor health outcomes," Fried said.

The findings were published in the Journal of Gerontology.