Scientists have discovered a
sleep-promoting circuit located deep in the primitive brainstem that enables us
to fall into deep sleep.
This is only the second 'sleep
node' identified in the mammalian brain whose activity appears to be both
necessary and sufficient to produce deep sleep, said scientists at Harvard
School of Medicine and the University at Buffalo School of Medicine and
The research demonstrated that
fully half of all of the brain's sleep-promoting activity originates from the
parafacial zone (PZ) in the brainstem. The brainstem is a primordial part of
the brain that controls basic functions necessary for survival, such as
breathing, blood pressure, heart rate and body temperature.
The close connection of a sleep
centre with other regions that are critical for life highlights the
evolutionary significance of sleep in the brain, said Caroline E Bass,
assistant professor of Pharmacology and Toxicology in the UB School of Medicine
and Biomedical Sciences
and a co-author on the paper.
The scientists found that a
specific type of neuron in the PZ that makes the neurotransmitter
gamma-aminobutyric acid (GABA) is accountable for deep sleep.
They utilized a set of innovative
tools to precisely control these neurons remotely, in essence giving them the
ability to turn the neurons on and off at will.
"To get the precision
required for these experiments, we introduced a virus into the PZ that
expressed a 'designer' receptor on GABA neurons only but didn't otherwise alter
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,"
said Patrick Fuller, assistant professor at Harvard and senior author on the
These findings may translate into
new medications for treating sleep disorders, including insomnia, and the
development of better and safer anaesthetics, he noted.
The study was published in the
journal Nature Neuroscience