In normal brains, this causes drowsiness. In brains in which the chemical balance has been somehow disturbed, triggering this cascade could have the opposite effect, bringing alertness and increased brain function.
Azizi says that the seemingly counterintuitive approach of giving minimally conscious patients a drug that would cause normal people to feel drowsy is actually backed by a respectable amount of experience.
"This is similar to what we think is happening in patients with ADHD [attention deficit hyperactivity disorder]," he said. "We give them a stimulant, such as Ritalin, and it has a paradoxical effect, actually calming them down."
Emory's Wright says that this knowledge could perhaps lead to future treatment strategies for brain-damaged patients.
"There are plenty of other medicines out there that are GABA agonists," she said. "Now maybe these could be tried as well, and tried earlier in treatment, to see if there is an effect."
But why does it work for only some patients?
To understand this, Azizi says that the brain can be thought of like a computer. The "hardware" is the brain's structure, an intricate network of internal connections of neurons and nerves that form the circuitry of the brain.
The other component he terms the "software," the chemical and electrical impulses that race through this tangled web.
If the damage to the brain is a disruption of the "software," the structural circuitry of the brain may be preserved to the extent that a bit of a "reboot" -- such as that seen with a dose of Ambien -- may help restore the balance needed for the patient to wake up or communicate.
However, if the "hardware" is damaged, if the circuits themselves have been destroyed, then there is less of a chance that the drug will be able to restore any degree of normal function.
"The stipulation is that structurally, the brain cannot be damaged," Azizi said.
The fact that no two brain injuries are exactly alike means that it is unlikely that zolpidem will ever be viewed as a cure-all for every minimally conscious patient.
"It's not going to work for everybody," Wright said. "But under a doctor's supervision, this might be something worth trying."
Considering the possible benefits, this shot at a miracle may give family members a small ray of hope.
"They should talk to their doctor and say, 'Doc, have you tried this on my loved one?'" Azizi said. "There are relatively few side effects, and it may be beneficial."