New research from Georgetown University Medical Center (GUMC) may help explain why some people who take Ambien (zolpidem) have been observed walking, talking on the phone, and driving while not fully awake. The study suggests that while some powerful brain circuits are shut down when a patient takes the sedative, the drug activates other circuits. These findings may also help explain why Ambien has been shown to awaken the minimally conscious into a conscious state.

"Brain cells or neurons are highly reactive to incoming activity throughout life," said Molly M. Huntsman, PhD, corresponding author for the study in an announcement on the findings. "When brain activity is silenced, many neurons automatically react to this change. We see this in our study, which suggests that inhibitory neurons responsible for stopping neural activity are themselves shut down by zolpidem. The excitatory neurons, responsible for transmitting activity, are then allowed to re-awaken and become active again, without monitoring, because the inhibitory neurons are ‘asleep.’ "

According to the researchers, while the study suggests that zolpidem shuts down active neural pathways and perhaps then triggers others, the activation of this trigger is unknown.

"Nevertheless, the paradoxical activation of brain circuits by a powerful sedative definitely needs more attention in additional studies both human and in animal models," said Huntsman.

The study appears online in the Proceedings of the National Academy of Sciences.