Most people experience their mental states as weather — something that happens to them, not something they can influence. A difficult morning, low focus mid-afternoon, restless evenings: these feel like facts rather than variables. Andrew Huberman, professor of neurobiology at Stanford, argues otherwise. The chemistry underlying these states is not fixed. It responds to specific, learnable behaviours — and understanding which chemicals govern which states gives you something rare: genuine leverage over how you feel and function.
This episode of the Huberman Lab Podcast focuses on four neuromodulators — dopamine (more on this here), epinephrine, serotonin, and acetylcholine — that act as the master regulators of your mental experience. Each one shifts the brain into a different mode. Together, they determine whether you're alert or calm, creatively expansive or analytically sharp, motivated to act or content to rest. Knowing how to influence them deliberately is a form of literacy about your own mind.
Dopamine and epinephrine — also known as adrenaline — are chemically related and tend to work in concert. Together, they constitute the drive system: the neurochemical fuel behind motivation, alertness, and directed pursuit. When both are elevated, you feel focused, energised, and ready to act. When both are low, effort feels effortful in the wrong way — heavy rather than purposeful.
Epinephrine is the faster-acting of the two. It mobilises the body for action — raising heart rate, sharpening attention, releasing stored energy. Dopamine provides the directional quality: the sense that something is worth pursuing, the anticipatory pleasure of moving toward a goal. Neither is useful without the other. Epinephrine without dopamine is agitation. Dopamine without epinephrine is wistful desire without the energy to act.
Serotonin is frequently misunderstood as simply the "happy chemical." The reality is more specific. Serotonin promotes a state of present-moment contentment — a sense that what you have now is sufficient. Where dopamine drives you toward future rewards, serotonin anchors you to present sufficiency.
The implications for wellbeing are significant. Low serotonin is associated with rumination, social withdrawal, and a persistent sense that something is missing. High serotonin, by contrast, produces a quality of ease — the kind of equanimity that allows you to engage fully with what's in front of you without restless craving for what isn't.
Huberman highlights two particularly powerful serotonin levers: exposure to natural sunlight and genuine social connection. Both are behaviours that consistently elevate serotonin through well-understood neurochemical pathways. The gut microbiome also plays a role — producing the majority of the body's serotonin and responding to diet, sleep quality, and physical activity. Gratitude practices, specifically the act of genuinely receiving gratitude rather than simply expressing it, activate serotonin circuits in ways that measurably shift mood.
Acetylcholine is the neuromodulator most directly linked to focused attention. It acts as a signal of salience — essentially telling the brain that what it is currently attending to matters and should be processed more deeply. When acetylcholine is released in the context of focused work, it creates what Huberman describes as a "spotlight" effect: sensory processing narrows, distractions recede, and the task at hand is encoded more richly.
This is why deliberate visual focus — fixing your gaze on a specific point at working distance before beginning a cognitively demanding task — can prime acetylcholine release and improve the quality of subsequent concentration. The visual and attentional systems share circuitry, and using one to engage the other is a practical, zero-cost protocol.
One of the most practically useful insights in this episode is that neuromodulators follow a daily pattern. In the early morning, dopamine and epinephrine tend to dominate — which is why many people find focused, motivated work easier in the first half of the day. Through the afternoon and into evening, serotonin tends to become more prominent — supporting social ease, relaxation, and recovery.
Understanding this rhythm allows for intelligent scheduling. Reserve high-stakes cognitive work for the morning window when alertness chemicals are naturally elevated. Use the afternoon for collaborative or creative tasks where diffuse, serotonin-dominant thinking is an asset rather than a liability. Avoid fighting the rhythm — work with it.
Caffeine deserves specific mention. It works primarily by blocking adenosine — the compound that builds up during waking hours and creates the sensation of tiredness. Delaying caffeine intake by 90 to 120 minutes after waking allows adenosine to clear naturally first, preventing the afternoon energy crash that results from suppressing rather than clearing early-morning adenosine accumulation.
A theme that runs through this episode — and increasingly through neuroscience more broadly — is the bidirectional communication between the gut and the brain. The microbiome produces a substantial portion of the body's serotonin. It also influences dopamine metabolism and immune function. Diet, sleep, and exercise all shape the microbiome, which in turn shapes mood, motivation, and cognitive clarity.
This is not a metaphor. The vagus nerve carries direct signals from gut to brain. The health of your gut bacteria measurably affects your neurochemistry. Fermented foods, adequate dietary fibre, and consistent sleep appear to support a microbiome composition associated with better mood and cognitive performance.