Introduction: Perception of sleep and wakefulness mechanisms need for the treatment of sleepiness neurological diseases. There are many differences regions in the brain involved in sleep and wakefulness control system. These regions affect physiological mechanisms of sleep. The awaking and sleep are strongly conserved throughout control by many types of neurotransmitter factors. Adenosine, nitric oxide, and GABAergic neurons play the main role in regulation of sleep and wakefulness in the brain. Changes in the neurochemical systems regulated sleep and wakefulness are accompanied by increasing the electroencephalogram activities. Non-rapid-eye-movement (NREM sleep) and rapid-eye-movement (REM sleep) are two types of sleep. The first one leads to memory consolidation and modulation of synapse, and the second one causes muscle atonia and regulation of emotion. Conclusion: Sleep disruption occurred with the paradox functions of NREM and REM sleep. Disturbation of physiologic states NREM and REM sleep may lead to cognitive impairments. In this review, we study the physiological mechanisms of sleep and wakefulness as well as the disorders associated with changes in neurochemical systems of sleep.