People tend to have trouble getting into and staying asleep when they grow old. Latest study explains that the loss of certain brain cells may be responsible for sleeping problems.
A study conducted by the researchers at Beth Israel Deaconess Medical Center (BIDMC) and the University of Toronto/Sunnybrook Health Sciences Center reveals why people experience sleeping problems.
Clifford B. Saper, Chairman of Neurology at BIDMC and James Jackson Putnam Professor of Neurology at Harvard Medical School explain that people in their 70s sleep around one hour less at night when compared to a person in their 20s. Sleep loss as well as sleep fragmentation may be linked with several health concerns, which includes high blood pressure, cognitive dysfunction, vascular diseases and more. However, this is the first time that scientists have found that the drops in levels of inhibitory neurons from the brain may also result in lack or disruptive sleep.
In a 1996 study, researchers found that a set of inhibitory neurons called ventrolateral preoptic nucleus functioned like a sleep regulator in lab rats. This group of neurons turns off the rat's brain arousal systems, which enables it to sleep.
The study also revealed that the loss of this set of neurons resulted in intense insomnia in the rats and they slept for around half the time they would normally. The sleeping pattern in the rats was also recorded to be disrupted.
The scientists reveal that the human brain also inhibits a set of cells called the intermediate nucleus that has identical inhibitory neurotransmitters called the galanin, which is similar to the ventrolateral preoptic nucleus in rats. The authors of the study hypothesize that in case the ventrolateral preoptic nucleus in rats and the intermediate nucleus in humans have similar function then the nucleus may also regulate sleep in humans.
To test the hypothesis, the researchers analyzed data of 1,000 healthy brains at age 65 years till death. When alive, these individuals had confirmed the donation of their brain for research after they die. The scientists then shortlisted and studied the brains of 45 subjects who wore a sleep tracking device to monitor their sleeping patterns when they were alive.
"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," says Saper. "The fewer the neurons, the more fragmented the sleep became."
The study concludes that ventrolateral preoptic nucleus in humans usually affects sleep. The loss of these neurons results in lack of sleep in individuals. The results of the study may be used by researchers to find ways to reduce sleep issues in elderly people.
