Researchers identify part of brain essential to sleep
Shane McGlaun – Oct 9, 2018 0

For the millions of people around the world who suffer from problems with sleep, new research could one day help them catch some shut-eye. Researchers have identified what they say is the “sleep switch” for the brain. The new research builds on a discovery made 20 years ago that identified a set of nerve cells believed to be associated with allowing the brain to turn off and sleep.

The new study published in “Nature Communications” this week builds on that decades-old research by Clifford B. Saper, MD/PhD, Chairman of the Department of Neurology at Beth Israel Deaconess Medical Center (BIDMC). In the new study, Saper and his team demonstrated in mice that the “sleep switch” cells are in a region of the hypothalamus called the ventrolateral preoptic nucleus or VLPO. Those cells are said to be essential to normal sleep.

The scientists worked with genetically engineered mice and artificially activated the VLPO neurons using different tools. In one test the neurons were activated using a laser light to make them fire. Another test used a chemical to selectively activate the VLPO neurons. The researchers say that activating these cells had a profound effect on sleep.

Damage to these cells causes insomnia say the scientists, people also lose these cells as part of the natural aging process according to the team. Saper and his team also found a reason for past research that found activating these VLPO neurons caused lack of sleep. Saper notes that his team found that how fast you stimulate these cells is critical to their function.

When the VLPO cells are stimulated one to four times per second, they fire each time they are stimulated resulting in sleep. Fire them faster than that and they fail to fire and eventually stop firing completely. That causes lack of sleep. Saper says that his team found that researchers in past studies were firing the VLPO cells ten times per second, causing them to shut off. These same cells also help regulate body temperature. Saper’s team believes that the decline in body temperature that happens when these cells are continually activated could account for how animals hibernate in the winter. The relationship between sleep and body temperature will be studied in future research.