Mood

Mood is a sustained affective state — a background tone of feeling that colours experience over hours or days rather than minutes. Unlike an emotion, which is a brief, targeted reaction to a specific event, mood persists without needing a particular trigger to maintain it.

Psychologists typically describe mood along two dimensions: valence (how pleasant or unpleasant) and arousal (how energised or subdued). Most people move through mild fluctuations along these axes over the course of a day; when shifts become extreme or prolonged, they shade into clinically recognised conditions.

On these pages, mood appears twice: as a quality that substances alter while they are active, and as a state that often shifts in the opposite direction once they clear.

How it works · its role

Mood is regulated by several overlapping neurotransmitter systems — principally serotonin, dopamine, and norepinephrine — that set a tonal baseline for neural activity across the brain. These systems project widely from small clusters of neurons in the brainstem and midbrain, reaching circuits involved in reward, threat detection, attention, and motivation.

The balance among them matters as much as any single signal. Serotonin is thought to set a general hedonic floor; dopamine tracks reward and anticipation; norepinephrine governs arousal and stress responsiveness. The stress hormone cortisol, released via the HPA axis, exerts a slower modulatory influence on all three.

Circadian rhythms layer on top of this chemistry, producing the diurnal mood patterns most people notice — which is part of why disrupted sleep and pharmacological shifts often compound one another.

Relevance to substances & effects

Nearly every class of psychoactive substance touches mood — often as the primary sought effect. Stimulants and empathogens such as MDMA produce acute mood elevation by driving monoamine release. Opioids shift mood via opioid receptors, producing a hedonic warmth qualitatively distinct from stimulant-driven arousal.

Serotonergic psychedelics do not simply elevate or suppress mood; they amplify and destabilise it, making the user's entry-point state a strong predictor of the experience's character. Cannabis can move mood in either direction depending on dose and set.

The period after a substance clears is as significant as the peak. A sharp monoamine surge tends to leave depleted neurotransmitter availability in its wake — producing the low mood, blunted motivation, and emotional flatness commonly reported in the hours or days following MDMA or stimulant use. This rebound pattern recurs across many substance pages in this reference.