Uses Of Melatonin For Aggressive Behavior

Melatonin, a hormone that helps regulate sleep and wake cycles, has been shown to have different effects on aggressive behavior, depending on the species of animal. Aggression refers to an intent to harm. Most of the research studying melatonin's effects on aggression has focused on animals, since it's unethical to attempt to induce aggressive behavior in humans because it can result in harm to others.

Decreased Aggression

Injections of melatonin resulted in a reduced aggressive response in a cichlid fish, found a 1986 study published by A.D. Munro in the "Journal of Pineal Research." Serotonin activity also decreased aggressiveness. The researchers suggested that serotonin may have this effect because it is a precursor to melatonin.

Increase Aggression

Melatonin may increase aggression in some species. Male Syrian hamsters were given melatonin 2 hours before lights out, simulating a winter-like short day, and showed increased aggression, according to a 2002 study published by Aaron M. Jasnow and colleagues in "Hormones and Behavior." The researchers suggested that melatonin may have increased aggression because of the nocturnal nature of the species. Melatonin may also promote aggression in mice, according to a 1981 study published by Anna T. Paterson and Colin Vickers in "Physiology and Behavior."

No Effect

Serotonin, a precursor to melatonin, plays a role in inhibiting aggressive behavior in people with personality disorders, states a 1998 study published by Emil F. Coccaro and colleagues in the "Archives of General Psychiatry." However, in humans, administering melatonin is not associated with a difference in mood, including anger or hostility, according to a 1984 study published by Harris R. Lieberman and colleagues in "Brain Research."