While some previous work suggests that midazolam-induced light sedation results from the functional disconnection within resting state network, little is known about the underlying alterations of cerebral blood flow (CBF) associated with its effects. A randomized, double-blind, within-subject, cross-over design was adopted, while 12 healthy young volunteers were scanned with arterial spin-labeling (ASL) perfusion MRI both before and after an injection of either saline or midazolam. The contrast of MRI signal before and after midazolam administration revealed the CBF decrease in the bilateral mesial thalamus and precuneus/posterior cingulate cortex (PCC). These effects were confirmed after controlling for any effect of injection as well as head motions. These findings provide new evidences that midazolam-induced light sedation is related to the disruption of cortical functional integration, and have new implications to the neural basis of consciousness.