1. age ≥ 18 years;
2. presence of unresponsive wakefulness syndrome (UWS) or minimally conscious state (MCS) on admission;
3. time since onset > 4 weeks;
4. no history of neurodegenerative or psychiatric diseases.

All patients were administered 10 mg of zolpidem tartrate tablets via a feeding tube and received EEG-reactivity test.

Healthy volunteers without any history of autonomic or any other nervous system disorder were included in this study. They were administered 10 mg of zolpidem tartrate tablets orally.

All participants were administered 10 mg of zolpidem tartrate tablets either via a feeding tube (for patients with prolonged disorders of consciousness) or orally.

The consciousness was independently assessed using CRS-R six months after enrollment by a trained neurologist blinded to the clinical data. Patients who transitioned from UWS to MCS (UWS-MCS) or to emergence from MCS (EMCS) (UWS-EMCS), from MCS minus to MCS plus (MCS--MCS+) or to EMCS (MCS--EMCS), and from MCS to EMCS (MCS-EMCS) were categorized in the improved consciousness group. The unimproved consciousness was defined as a reduced or unchanged level of consciousness at six months.