Serotonin Signalling

Serotonin

Monoamine made from tryptophan. Mostly gut-resident, and the precursor of melatonin.

Serotonin 5-HT2A Receptor

A serotonin receptor involved in mood, impulse control and aggression. Androgen exposure shifts serotonergic signalling in animal work, which is the mechanistic case behind steroid irritability.

Aggression

Hostility and short fuse. Reported consistently by users and in case series, and produced in blinded trials mainly at supraphysiological doses and mainly in a minority of people.

Irritability

A lower threshold for annoyance, distinct from outright aggression and far more commonly reported.

Executive Function

Planning, switching between tasks, and holding back a response you are about to make. The last of those is the one that matters here: reported aggression on these compounds is often better described as a failure of the brake than as an increase in anger.

Raphe Nuclei

The brain's serotonin source. It sets patience, satiety with a situation and the threshold at which irritation becomes an outburst. Adolescent steroid exposure changes serotonin signalling in animals, and the change reverses direction on withdrawal.

Sleep Quality

How restorative sleep is, as opposed to how much of it there is. Deep and REM sleep are where growth hormone is released and where memory is consolidated, so this is the measure that connects a sleep effect to a memory effect. A person can sleep eight hours and get almost none of this.