Withdrawal syndrome is a set of complaints caused by stopping the use of a psychoactive substance. The appearance of withdrawal disorders is determined by the period of abstinence from the use of addicted substances and the length of its duration. The gradual withdrawal of alcohol, as a slow-acting substance, determines a relatively longer period of the onset of withdrawal syndrome than when withdrawing from narcotic drugs (the abstinence period of which is much shorter, and the period of formation of the withdrawal syndrome is much shorter). The first signs of an approaching alcohol withdrawal crisis are sleep.