{"id":44100,"date":"2022-02-17T12:21:56","date_gmt":"2022-02-17T15:21:56","guid":{"rendered":"http:\/\/condorinst.com.br\/?p=44100"},"modified":"2026-08-24T12:11:30","modified_gmt":"2026-08-24T15:11:30","slug":"melatonina-qual-e-sua-relacao-com-o-sono-e-ritmos-biologicos","status":"publish","type":"post","link":"https:\/\/condor.fabbricaweb.com.br\/en\/melatonina-qual-e-sua-relacao-com-o-sono-e-ritmos-biologicos\/","title":{"rendered":"Melatonin: what is its relationship with sleep and biological rhythms?"},"content":{"rendered":"\n

Melatonin is a hormone found in practically all living organisms and is produced in the pineal gland, secreted into the blood and then acting as a hormone (AMARAL; CIPOLLA-NETO, 2018<\/a>). The circadian timing system controls its production, so that in the presence of light, its production is inhibited and, conversely, in the absence of light, its production is stimulated. Thus, its synthesis is aligned with the light-dark cycle. Its effects on the body are diverse and can be observed even when there is no more melatonin present in the body, a factor that makes it difficult to delineate its functions as in other hormones (CIPOLLA-NETO; AMARAL, 2018<\/a>). For the purpose of this article, the effects that melatonin has on sleep and biological rhythms will be discussed, as well as some conditions that can interfere with its synthesis.<\/p>\n\n\n\n

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Due to its circadian component, the concentration of melatonin increases during the night and decreases during the day, which is why the idea has been built up that it is a sleep hormone. However, this statement is a mistake. In nocturnal species, i.e. species whose activity period is concentrated during the dark phase of the day, it is possible to observe that the melatonin curve follows the same pattern as that of diurnal species (humans, for example). Interestingly, melatonin only has sleep-inducing effects in predominantly diurnal species (CIPOLLA-NETO; AMARAL, 2018<\/a>; LIU; WEAVER; JIN; SHEARMAN et al.<\/em>, 1997<\/a>).<\/p>\n\n\n\n

When sleeping during the light phase of the day, when there is not much melatonin in the body, sleep has a more fragmented architecture and a shorter duration. Furthermore, when melatonin secretion is blocked at night, either through pharmacological intervention or light, the same fragmented pattern is observed (CAJOCHEN; KR\u00c4UCHI; DANILENKO; WIRZ-JUSTICE, 1998<\/a>; VAN DEN HEUVEL; REID; DAWSON, 1997<\/a>). Obviously, when trying to sleep during the day there are other components that will influence the quality and duration of sleep, such as high core temperature and higher cortisol concentration, but these results demonstrate the potential of melatonin to induce and improve sleep quality. Studies carried out on pinealectomized humans reinforce this data. These patients generally have rhythms that are out of sync with the 24-hour light-dark cycle, reduced total sleep time, a high volume of awakenings during the night and poor sleep quality. In most cases, these symptoms were reversed with the administration of exogenous melatonin (ETZIONI; LUBOSHITZKY; TIOSANO; BEN-HARUSH et al.<\/em>, 1996<\/a>; LEHMANN; COCKERELL; RUDGE, 1996<\/a>). A systematic review conducted by Brzezinski and colleagues sought to evaluate the effects of exogenous melatonin administration on sleep parameters. The results show a reduction in sleep onset latency, as well as an increase in total sleep time and sleep efficiency (BRZEZINSKI; VANGEL; WURTMAN; NORRIE et al.<\/em>, 2005<\/a>). Furthermore, as mentioned by Cipolla Neto, most studies standardize the dosage of melatonin used, and this can reduce the size of the effect observed (CIPOLLA-NETO; AMARAL, 2018<\/a>).<\/p>\n\n\n\n

Another important function of melatonin is the regulation of the sleep-wake cycle. This role as a chronobiotic can be used to regulate rhythm disorders such as delayed\/advanced sleep phase syndrome and non-24-hour rhythm. It is necessary to look at the desired objective in order to define the time at which it should be taken. If you take it at the beginning of the night, the sleep phase is advanced. On the other hand, taking it at the end of the night delays the sleep phase. There is also a “dead zone” in which no rhythm-related adaptations are observed when eating at this time. This zone is located in the middle of the night, when melatonin acrophase usually occurs (CIPOLLA-NETO; AMARAL, 2018<\/a>).<\/p>\n\n\n\n

Conditions that cause a reduction in the concentration of endogenous melatonin<\/strong><\/em><\/h2>\n\n\n\n

            <\/em>Some conditions affect melatonin production, either too much or too little. From a clinical point of view, dysfunction in melatonin production can be classified as:<\/p>\n\n\n\n