“Sensitisation leads to high spikes of dopamine in response to cues and triggers associated with use. The dopamine spikes occur before ingesting the drug or masturbating to porn, and are experienced as cravings to use. However, on exposure to the same old stimuli less dopamine (and less opioids) are released (desensitisation). This dampening of pleasure occurs during drug use or while masturbating to porn. The activity is experienced as less pleasurable, increasing cravings for more.”