The psychological causes of addictiveness and addiction have been studied quite thoroughly. Biological factors continue to be investigated. How are endorphins involved in addiction? “In our body, as well as in the bodies of all living beings on this planet, substances with analgesic ability similar to morphine are produced. They began to be called endogenous (that is, internal) morphines - endorphins. <...> Today the number of opioids (endorphins) is , according to some data, a little more than 40, and according to others, it exceeded 50,” says Doctor of Biological Sciences, Professor S.B. Parin in the book "Stress, pain and opioids. About endorphins and more", 2021. Endorphins can play the role of: 1) hormones (produced by the cells of the endocrine glands, regulate metabolism and other functions); 2) mediators (synthesized in the brain, provide transmission of excitation at the synapse - contact between neurons). Peptides act as endorphins - mediators. Peptides are microproteins with molecular sizes larger than those of classical mediators (adrenaline, norepinephrine, serotonin, dopamine, etc.) “Just like proteins, peptides are a chain of amino acids. <...> Peptides are always short chains, no more than a few dozen amino acids" (S.B. Parin, 2021). Endogenous morphine-like peptides are called "opioids" (or "opioid peptides"). Some of the shortest opioids synthesized in the brain are enkephalins or “brain” peptides. The discovery of opioids in the last third of the twentieth century necessarily required scientists to discover receptor proteins. The researchers understood that only receptors located on the neuron membrane are able to recognize the mediator (signal molecule) and transmit the information it brings further into the cell. The search began for areas of the brain where these receptors might be most abundant. They turned out to be some areas of the brain stem, the hypothalamus and the limbic system, which is responsible for the formation of emotions and motivation. S.B. Parin writes: “In just a few years, knowledge has developed that both opioid peptides and opiate receptors for them are found in the bodies of various animals. It all started with mammals: rats, rabbits, mice, dogs, monkeys, but then they began to accumulate data about other classes and types, including the protozoa. I think at that time - in the 70s - 80s of the last century - no one could even imagine that 30 years later it would become clear: everything has opioids and their receptors (I emphasize: everything! ) living on Earth. It soon became clear that opioid peptides and their receptors, cells that produce these peptides and cells that respond to them, as well as transport flows in the case where opioids perform a hormonal function, form a unified system of regulation and information transmission. The name “endogenous opioid system (EOS)” has been assigned to this entire complex. And today we can claim that this is the most ancient regulatory system on our planet. Being information molecules, endorphins, like hormones, remotely control metabolism in a wide variety of cells or, as mediators, they act on a neighboring cell through a synapse. Endorphins are slow hormones: from endocrine cells ("parents") to target cells, they have a slow path through the blood, lymph, and cerebrospinal fluid. But the result of their action is prolonged. Endorphins are fast-moving transmitters: their channel (synapse) is just a narrow gap between neighboring cells. The action of mediators “is very fast, very targeted and very effective, but there can be big problems with long-term preservation of the result” (S.B. Parin, 2021). Pain, stress, goal setting, motivation, self-esteem, trance, sports, sex, food, watching movies, listening to music... Opioids are making themselves known everywhere. Endorphins have the ability to reduce pain and affect the emotional state. This is how they attract the attention of pharmacologists, marketers, teachers, psychologists, NLP specialists (trainers - hypnologists, + 7 898 105 7305