Researchers from the Stanford University School of Medicine have identified a brain circuit that plays a key role in the sleep-wake cycle.
In the mice study, which was published in the journal Nature Neuroscience on Sept. 5, study researcher Luis de Lecea and colleagues found that the activities in the newly identified brain circuit decrease when the animals involved in the study ramped down for sleep. Activating the circuit, on the other hand, was found to rouse the mice from sleep.
Figures from the U.S. National Institutes of Health show that between 25 to 30 percent of Americans suffer from sleep problems. The researchers said the findings of the study may potentially pave way for new targeted treatments that could address sleep problems.
The researchers said that insomnia, a common sleep disorder that drives a multibillion dollar market for drug companies, is traditionally treated with drugs such as benzodiazepines that shut down the entire brain. The findings offer potentials for new therapies that narrowly target the newly identified brain circuit to induce better sleep quality.
The brain circuit was also found to be a key component of the reward system. Although it makes sense that the reward system that motivates goal-directed behaviors such as looking for food and escaping from predators coordinates with the sleep-wake cycle such that people do not typically look for food in their sleep, no anatomical location for this association has been pinpointed until this study.
Although the study was conducted in mice, the circuitry of the reward system is similar in all vertebrates to the chemical dopamine known to play an important role in firing up this circuitry.
"We have plenty of drugs that counter dopamine," said study researcher Ada Eban-Rothschild. "Perhaps giving a person the right dose, at just the right time, of a drug with just the right pharmacokinetic properties so its effect will wear off at the right time would work a lot better than bombarding the brain with benzodiazepines, such as Valium, that knock out the entire brain."
Since sleep-wake cycle disturbances are also prevalent in people who have schizophrenia and bipolar disorder, the researchers said that there is the potential for drugs that target the dopamine-secreting nerve cells of the ventral tegmental area or VTA to help those with these neurological problems who suffer from sleep problems.
The VTA is a brain structure widely associated with the natural reward circuitry of the brain.
