Recent research has made huge strides in demystifying sleep -- why we need it, how to get more of it, and what happens when we don't get enough of it. But there's still a lot that remains largely unknown, including the way brain circuits control the sleep-wake cycle. Until now, that is.
In a landmark study, neuroscientists at the University of Bern in Switzerland discovered a pattern of brain activity that is responsible for waking us up from light sleep and anesthesia.
"These findings identify a new network and refine our understanding of the brain network that regulates sleep and wake cycle," Dr. Antoine Adamantidis, a neuroscientist at the university and the study's lead author, told The Huffington Post in an email.
The study, which was published on Dec. 21 in the journal Nature Neuroscience, showed that activating the circuit associated with the rhythms of electrical activity that occur during sleep -- which is located between the hypothalamus and thalamus brain regions -- causes rapid wakefulness. While, inhibiting the circuit deepens sleep.
For the study, the researchers used a new technique called "optogenetics" on mice, inserting light-reactive genes into certain neurons in the rodents' circuit and then "turning on" those neurons via light pulses.
When the researchers activated the neurons in the circuit, they were able to induce rapid awakening from sleep. And when they stimulated these neurons for an extended period, the mice stayed awake. However, when the researchers inhibited the neurons in the circuit, the mice slept longer, more intensely, and with fewer interruptions.
What's more, the arousing power of this brain circuit was so strong that it even led the mice to regain consciousness after being put under anesthesia.
Adamantidis called the discovery "exciting" as it could lead to new methods for therapeutical approaches to waking someone from a vegetative or minimally conscious state. So far, such methods have been limited.
The researchers say the new discovery may also lead to more targeted treatments for insomnia or sleep disturbances, once they are able to determine how malfunctions in the brain circuit are related to sleep issues.
"It’s a big question in the field," Adamantidis said. "Possibly those circuits may become hypersensitive to certain inputs, so their hyperactivity may delay the sleep onset, and may also results in fragmented sleep -- two hallmarks of insomnia."
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