Sedative-hypnotics are a class of central inhibitor, whose inhibition on the central nervous system increases gradually with the increasing dose. They produce sedative effect with a small dose, to calm a person and release his anxiety and irritability without depriving his consciousness and normal motor function. Moderate doses will cause a sleep state close to physiological sleep and large doses can lead to anesthetic and anticonvulsant. But with a toxic dose, it can cause significant central inhibitor, drowsiness, respiratory paralysis and even death.
The hypnotic effect mechanism of these drugs has not been elucidated. Electrophysiological studies demonstrated that hypnotic depresses the ascending activating system of the reticular, weakens its function of maintaining the awareness of the cerebral cortex, results in sleep. Experimental data indicate that these drugs have a effect of promoting γ-aminobutyric acid (GABA), a central inhibitory neurotransmitter.
The abuse of sedative-hypnotics happens around the world nowadays. Long-term use of sedative-hypnotics will lead to physical dependence and withdrawal symptoms once the intake is cut off, and even convulsions in severe cases. Some hypnotics such as barbiturates can shorten the time of REM sleep, once withdrawn from long-term intake , can result in the rebound phenomenon where the time of REM sleep is significantly prolonged, with the adverse reaction of dreaminess.