Scientists say the discovery of a sleep-promoting "node" or circuit deep inside the primitive lower stem of our brains is revealing how we attain a level of deep sleep and could lead to new therapies for sleep disorders.

As per researchers at Harvard University and the University at Buffalo in New York, the "node" is just the second one detected in the mammalian brain linked to the ability to achieve deep sleep.

The new node, reported in the journal Nature Neuroscience, where fully half of all the brain's sleep-promoting activity takes place, is known as the parafacial zone, or PZ, of the brainstem,

The brainstem is the most primitive and ancient part of our brains. It regulates the most basic functions needed for our survival, including breathing, heart rate, body temperature and blood pressure.

The findings are evidence that sleep, and our ability to achieve a deep level of sleep, is just as basic as an evolutionary survival necessity.

"The close association of a sleep center with other regions that are critical for life highlights the evolutionary importance of sleep in the brain," says Buffalo professor of pharmacology and toxicology Caroline E. Bass.

A specific type of neuron in the parafacial one creates a neurotransmitter known as gamma-aminobutyric acid, or GABA, a messenger chemical that initiates the series of steps necessary to attain deep sleep.

The researchers discovered a technique to precisely control the GABA neurons remotely in animal test subjects without otherwise affecting brain function.

"When we turned on the GABA neurons in the PZ, the animals quickly fell into a deep sleep without the use of sedatives or sleep aids," says Harvard researcher Patrick Fuller, the study's senior author.

The new study findings and the accompanying experiments could lead to new medications for treating sleep disorders including insomnia, and the development of safer and more effective anesthetics, the researchers say.

"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," says Bass.

The primary function of deep sleep, also known as slow-wave sleep, is to allow the brain a chance for "rest and recover" from its daily activities.

It is also considered important for consolidating new memories from the waking hours of the previous day, experts say.