Why do Older People Sleep Less?

You might think that the stresses of daily life and increased physical challenges might cause older people to sleep more. But, as we know, often the opposite is true. People over 70 tend to have more trouble sleeping than they did in their youth. Now scientists at Boston’s Beth Israel Deaconess Medical Center, Rush University in Chicago and the University of Toronto may have spread light on why this is. In previous research done at Beth Israel a link was made linking a chemical called galanin and sleep. They identified a type of brain cell that’s active mainly during sleep. When these neurons fire, they release galanin, which quiets brain signaling, leading to sleep. These cells are found in the brains of mice, cats, and monkeys. Lab animals deprived of these cells slept about half as much as those with them. Similar cells have been seen in humans, but it was not clear if they controlled sleep the same way as they did in animals. A new study, published in the journal, Brain, relies on a Rush study of 1,000 older people who were followed for 15 to 20 years. They periodically wore a wristband that monitored their activity and indicated when they were asleep. With 45 study participants, the Beth Israel researchers were able to match post-mortem cell counts of the galanin-producing cells with the person’s sleep patterns when they were alive. It showed that the numbers of these nerve cells are reduced in older people, especially those with Alzheimer’s disease. The people with the most of these nerve cells left slept the best and the ones with the least slept the worst. Sleep is now increasingly recognized as important to health as exercise and nutrition are and one of the most common reasons for putting Alzheimer’s patients in nursing homes is there tendency to wake at night and wander. So, finding a way to help the sleep-deprived would have important medical benefits. A sleep researcher at the David Geffen School of Medicine at the University of California Los Angeles who was not involved with the study, Ronald Szymusiak, said, “Because the cells release the neurotransmitter galanin it is possible that adding galanin to the brains of older people and Alzheimer’s patients will help correct sleep problems.” But, he is not aware of any research being conducted on this now.