Research Explains Why Old People Sleep Less

As people grow older, they lose brain cells that act as "sleep switch". The researchers say that this reduction in a certain kind of cells reduces quality of sleep in seniors.

The study was conducted by researchers at the Beth Israel Deaconess Medical Center in Boston. The team says that sleep loss in old people, particularly those with Alzheimer's disease, can result in wandering and night time confusion, HealthDay reported.

The study is published in the journal Brain. Past research has shown that old people tend to sleep less or have fragmented sleep. The current study is important because it shows the reason behind sleep deprivation.

"On average, a person in his 70s has about one hour less sleep per night than a person in his 20s," explains senior author Clifford B. Saper, MD, PhD, Chairman of Neurology at BIDMC and James Jackson Putnam Professor of Neurology at Harvard Medical School, according to a news release. "Sleep loss and sleep fragmentation is associated with a number of health issues, including cognitive dysfunction, increased blood pressure and vascular disease, and a tendency to develop type 2 diabetes. It now appears that loss of these neurons may be contributing to these various disorders as people age."

Data for the study came from Rush Memory and Aging Project. The project includes 1,000 people who were enrolled in the study when they were 65 years old, back in 1997. These people were followed until they died, at which point their brains were donated for research. The participants even agreed to wear devices on their wrists that monitor their movement.

Scientists said that ventrolateral preoptic neurons regulate sleep patterns. The team found that people with AD lost more neurons than those without the disease. Reduction in the number of ventrolateral preoptic neurons was associated with sleep problems.

"We found that in the older patients who did not have Alzheimer's disease, the number of ventrolateral preoptic neurons correlated inversely with the amount of sleep fragmentation," said Saper in a news release. "The fewer the neurons, the more fragmented the sleep became."

Dana Foundation Clinical Neuroscience Grant and National Institutes of Health supported the research.