Reduction of Brain Neurons Affects Sleep Quality in Seniors: Study

Scientists at the Beth Israel Deaconess Medical Center (BIDMC) and the University of Toronto's Sunnybrook Health Sciences Center discovered that during old age the 'ventrolateral preoptic neurons' that serve as a 'sleep switch' in the brain undergo massive deterioration. This causes sleep disturbances and loss in seniors and for those with mental diseases like Alzheimer's, reports the Business Standard.

The experts conducted the experiment using a rodent model and discovered the loss of these neurons caused chronic sleep deprivation. The rats could only get 50 percent of normal shut eye than before. Following this trial, the research team investigated brain health, structure and sleep quality in 1,000 healthy participants aged above 65. The subjects' were followed from 1997 until death, and a majority of the brains were donated for further examination.

During the research, seniors wore a small device around their wrist that recorded total sleep quality and duration for almost 10 days. At the end of the study period 45 participants died whose brains were examined to assess the remaining amount of ventrolateral preoptic neurons.

"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 Clifford B. Saper, senior author and chairman of Neurology at BIDMC in a news release.

"The fewer the neurons, the more fragmented the sleep became. These findings provide the first evidence that the ventrolateral preoptic nucleus in humans probably plays a key role in causing sleep, and functions in a similar way to other species that have been studied," he adds.

 Insomnia and sleeplessness have been linked to cognitive and memory decline in old age. Erratic sleep cycle also affects quality of life, work and health. The authors believe their results helps design new strategies to treat insomnia and sleep disorders to avert risks of mental disorders in later years.

More information is available online in the Journal Brain.