New 'Sleep Node' Deep in the Brain Causes Sleep without Sedatives

Some patients have a hard to getting to sleep. Yet using sedatives on a regular basis can promote dependency. Now, researchers have discovered a sleep-promoting circuit located deep within the brain that may just help them develop new ways to help people fall asleep at night.

The recently discovered circuit is located deep within the primitive brainstem. It's actually only the second "sleep node" to be identified in the mammalian brain whose activity appears to be both necessary and sufficient to produce sleep.

In this case, the researchers found that fully half of all of the brain's sleep-promoting activity originates from the parafacial zone (PZ) in the brainstem. The brainstem itself is a part of the brain that regulates breathing, blood pressure, heart rate and other necessary functions for survival. They also found that a specific type of neuron in the PZ that makes the neurotransmitter gamma-aminobutyric acid (GABA) is responsible for deep sleep.

"The close association of a sleep center with other regions that are critical for life highlights the evolutionary importance of sleep in the brain," said Caroline Bass, co-author of the new paper, in a news release.

Yet actually seeing what was occurring wasn't easy. The researchers introduced a virus into the PZ in test animals that expressed a "designer" receptor on GABA neurons only but didn't otherwise alter brain function. When they turned on the GABA neurons in the PZ, the animals quickly fell into a deep sleep without the need for sedatives.

"We are at a truly transformative point in neuroscience, where the use of designer genes gives us unprecedented ability to control the brain," said Bass. "We can now answer fundamental questions of brain function, which have traditionally been beyond our reach, including the 'why' of sleep, one of the more enduring mysteries in the neurosciences."

The findings are published in the journal Nature Neuroscience.