Inclusion Criteria:  Adults (18 years and older) Patients admitted to ICU not more than 24 hours at the time of randomization  Exclusion Criteria:  Patients admitted to ICU less than 72 hours Patients receiving gabapentin within 14 days prior to randomization Patients receiving restorative drug (trazodone, mirtazapine, olanzapine, agomelatine, and pregabalin) within 7 days prior to randomization Patients having contraindications to gabapentin Patients receiving high dose vasopressors more than 1 hour during ICU admissions Patients presenting with severe respiratory failure (PF ratio < 100) Patients presenting with RASS < -2 at the time of randomization Patients having target RASS of <-2 during ICU admissions Terminal ill patients Pregnancy