Sleep is the mandatory transition that occupies 1/3 of our life. The research about sleep has been studied over 50 years, but not until recent days do we start to understand the brain reorganization of human sleep. Through the simultaneous EEG-fMRI recordings, we were able to study the changes of functional connectivity and spectral power during nocturnal sleep. Interestingly, we demonstrated the regional disparity during sleeping or upon awakening. The disclosed brain reorganization in sleep may serve as the key to investigate the sleep disorders or even the changes of consciousness levels in the near future.