A man who had been unable to talk or walk for eight years after choking on meat started speaking minutes after being given a sleeping tablet.
The patient, known as Richard, 37, asked how to operate his wheelchair and where he could find fast food within 20 minutes of receiving the pill.
He even managed to stand up, walk a few steps, asked to speak to his father and recognised his brothers.
But the effects wore off two hours after being given the drug and he returned to his original state.
Richard, of the Netherlands, developed akinetic mutism when he was 29 after his accident starved him of oxygen.
It also left him having to be fed through a tube, incontinent and reliant on nurses.
His doctor Willemijn van Erp revealed: “Because Richard’s situation seemed hopeless, the family and I decided to administer this medication.
"Against all expectations, zolpidem had remarkable effects. After taking the sleeping pill, he started talking, wanted to call his father, and started recognising his brothers.
“With help, he could even get up from his wheelchair and walk short distances.”
He had amnesia dating back to three years before the brain injury and hearing issues.
Scans revealed parts of his brain had shut down because they were being overloaded with sensory activity.
But the sedative muted the unwanted activity, allowing him to regain speech and movement for a couple of hours.
The restorative impact of the pill could be repeated once a day for around five days before the effect started to wear off.
Dr Hisse Arnts, at Amsterdam UMC, said: “The time windows during which the patient was able to talk and move got narrower, and his abilities to move and speak decreased.”
Akinetic mutism differs to paralysis and coma because patients may open their eyes and sometimes make sounds.
The researchers are looking into a long-lasting solution that could help Richard and others stay fully conscious.