What are hormones and neurotransmitters, how they affect you

TL;DR: What are hormones and neurotransmitters, and why they matter

• Hormones (slow-acting, long-range) and neurotransmitters (fast-acting, brain-based) are key chemical messengers shaping your mood, focus, energy, and sleep.

• When balanced, you feel calm, clear, and resilient; when imbalanced, you may feel wired, foggy, moody, or “off,” even with healthy habits.

• Hormones like melatonin and cortisol regulate stress, recovery, and your body’s internal clock.

• Neurotransmitters such as serotonin, dopamine, and GABA influence your moment-to-moment mood, focus, and reactivity.

• Daily habits: sleep, nutrition, movement, and stress; directly affect this balance.

• Tools like Muse can help you monitor and train your brain in real time to support healthy brain chemistry.

You know those days when you wake up tired, snap at the smallest thing, or can’t focus no matter how hard you try? That’s not just a bad mood. It’s chemistry. 

Behind every emotion, energy crash, or sleepless night are two powerful systems that may be the culprit: your hormones and your neurotransmitters.

Your body is constantly communicating with itself through a complex system of chemical messengers. Primarily hormones, which travel through your bloodstream to regulate processes like sleep, stress, and metabolism, and neurotransmitters, which transmit signals between neurons in your brain to influence mood, attention, and emotional regulation.

When this internal communication system is in balance, you feel calm, focused, and resilient. But when it's disrupted? Mood swings, brain fog, restless nights, and that feeling of being "off", even if you’re doing all the right things on paper.

Here’s a deep dive into what they are and how you can optimize them for better mood, sleep and stress management.

What are hormones?

Hormones are chemical messengers produced by your endocrine system, which is a network of glands that send signals through your bloodstream to organs and tissues. These messengers help regulate everything from metabolism and immune function to mood, stress, and sleep.
When hormone levels are out of balance, it can lead to a cascade of issues, such as stubborn weight gain, chronic fatigue, poor concentration, and difficulty coping with stress, even if you have the healthiest lifestyle and great habits. Your hormone levels naturally shift based on your sleep-wake cycle, stress levels, environment, diet, and even exercise regimen.

What hormones impact sleep, mood and stress?

Scientists have identified over 50 hormones and they are secreted by major glands like the hypothalamus, pituitary, thyroid, adrenal glands, pancreas, ovaries, and testes, creating a complex network of chemical communication that keeps your body in balance. Here are the main 10 that you may already be familiar with:

• Melatonin: Regulates sleep-wake cycles and circadian rhythm

• Cortisol: The primary stress hormone; governs energy, alertness, and recovery

• Estrogen: Supports reproductive health, bone density, and mood regulation

• Progesterone: Works alongside estrogen to regulate menstrual cycles and promote calm

• Testosterone: Drives libido, muscle growth, motivation, and assertiveness

• Insulin: Controls blood sugar and energy metabolism

• Thyroid hormones (T3 & T4): Regulate metabolism, energy, and body temperature

• Growth hormone (GH): Stimulates cell regeneration, muscle growth, and recovery

• Oxytocin: Supports bonding, trust, and social connection

• Adrenaline (epinephrine): Triggers the “fight or flight” response under acute stress

While we all produce these hormones, the timing and balance look different. Women typically experience cyclical shifts over a ~28-day menstrual cycle, while men follow a more stable 24-hour hormonal pattern. 

Check out this post about how the hormones related to menstrual cycles affect the brain:

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Hormones may not act as quickly as other chemical messengers, but they shape your energy, mood, and metabolism across your entire life, from puberty and reproduction to sleep and aging. When they’re in balance, you feel grounded, focused, and resilient. When they’re off, it’s like your internal rhythm is out of tune, no matter how “healthy” your habits seem.

But hormones are only part of the picture. For faster shifts in mood, focus, and emotional state, we also have neurotransmitters. Let’s take a look at how they work, and how they interact with your hormonal system.

What are neurotransmitters?

Neurotransmitters are fast-acting chemical messengers that carry signals across your brain and nervous system. Unlike hormones, which travel through the bloodstream to regulate long-term processes throughout the body, neurotransmitters are chemical messengers that transmit signals rapidly between neurons, primarily within the nervous system and from neurons to muscles.

Every thought you think, emotion you feel, or movement you make is powered by neurotransmitters firing across tiny gaps between nerve cells, called synapses. They regulate your mood, motivation, focus, energy levels, sleep cycles, in a matter of seconds.

While hormones help shape your overall emotional baseline over time, neurotransmitters influence your moment-to-moment mood shifts, motivation, mental clarity, and focus, often in a matter of seconds.

Muse’s headbands use EEG to track your brainwave activity and fNIRS to detect blood flow changes in the prefrontal cortex, these signals reflect patterns of neural activity and blood flow that are influenced by underlying neurochemical processes. This combination gives you a real-time view of your brain in action, helping you train for more calm, focus, and emotional stability over time. 

Key neurotransmitters that shape your mental state

Each of these brain chemicals plays a unique role in how you feel, think, and respond to the world around you.

These are some of the primary neurotransmitters responsible for regulating your brain’s fast-changing states:

• Serotonin: Influences mood, emotional stability, and sleep

• Dopamine: Linked to motivation, pleasure, and goal-directed behavior

• GABA (gamma-aminobutyric acid): The brain’s main calming signal; helps reduce anxiety and overactivity

• Acetylcholine: Supports learning, memory, and attention

• Norepinephrine: Increases alertness, focus, and energy during stress

• Glutamate: The brain’s main excitatory neurotransmitter; crucial for learning and cognition

When these chemicals are balanced, your brain runs efficiently and you feel alert, calm, and productive, similar to when you are in a flow state. However, when they’re out of sync you may feel scattered, low, overwhelmed, or mentally foggy, even without an obvious trigger.

Neurotransmitters can become imbalanced due to chronic stress, poor sleep, overstimulation, nutrient deficiencies, and even a lack of physical activity. 

Unlike hormones, which affect long-term patterns, neurotransmitters shift rapidly throughout your day responding to your environment, thoughts, and even your breath.

How hormones and neurotransmitters work together

Hormones and neurotransmitters may operate on different timelines, but they constantly interact to regulate your mental and physical state. Your body’s chemical messaging systems are deeply interconnected. 

Here’s a quick deep dive into how it all works:

The HPA axis, which is a chain reaction involving the hypothalamus, pituitary, and adrenal glands, is triggered by stress, releasing cortisol, which not only manages energy and arousal but also suppresses melatonin production, disrupting sleep and evening mood.

Meanwhile, neurotransmitter disruptions are both a cause and effect of hormonal imbalance: chronic cortisol exposure can reduce the effectiveness of serotonin and GABA signaling, increasing anxiety and mood instability.

Conversely, neurotransmitter systems help regulate hormone rhythms: serotonin serves as a precursor to melatonin, and GABAergic activity in the hypothalamus helps initiate melatonin release to wind down for sleep.

These feedback loops show how neurotransmitters and hormones collaborate to maintain balance, so when one falters, the other follows.

 

The major players in brain & body chemistry

Each of the brain and body chemicals below plays a distinct role. Together, their timing, balance, and interaction determine how you actually feel and function day to day.

Let’s break down the ones that matter most for sleep, stress, and mood:

Melatonin

Known as the sleep hormone, melatonin is released by the pineal gland in response to darkness. It helps regulate your circadian rhythm, which is your internal body clock that controls when you feel alert or sleepy. Light exposure (especially blue light) can suppress melatonin, which is why screen time before bed makes it harder to fall asleep.

Here are some tips to improve your night time routine to protect your melatonin. 

Cortisol

Cortisol is your primary stress hormone, released by the adrenal glands in response to physical or emotional stress. It helps regulate energy, metabolism, alertness, and inflammation. Cortisol naturally peaks in the morning to help you wake up and gradually decreases throughout the day. However, when you’re under chronic stress, levels can remain elevated, contributing to burnout, poor sleep, and mood dysregulation.

Learning how to stress less by breathing exercises or mindfulness exercises can help. Using Muse to track your brainwaves throughout the day can help you understand when you are the most calm. 

Serotonin

Serotonin is a neurotransmitter that helps stabilize mood, emotion, and sleep. It also plays a role in digestion and body temperature regulation. Low serotonin is associated with depression, anxiety, and poor sleep, while balanced levels help you feel calm, grounded, and emotionally resilient.

Practicing gratitude has been shown to naturally support serotonin production by activating brain regions linked to emotional regulation and connection. Learn more about the science of gratitude here →

Dopamine

Dopamine is often called the “motivation molecule.” It’s involved in reward, drive, learning, and attention. It gives you the feeling of satisfaction after completing a task or achieving a goal. When dopamine levels are dysregulated, it can lead to issues with motivation, focus, and even addictive behaviors.

You can support dopamine function by training your brain for deeper focus and presence. Explore how to train your brain for less stress here →

How to keep your brain chemistry in balance

Even if your brain and body are built to self-regulate, modern life often works against that system. Sleep deprivation, blue light exposure, multitasking, poor recovery, and chronic stress can all throw your hormones and neurotransmitters out of sync, leaving you feeling foggy, wired, or emotionally off-center.

The good news? You can support your brain chemistry naturally with small, science-backed shifts:

• Practice better sleep hygiene: A dark, cool room, comfortable bed, and a consistent bedtime. You can explore the benefits of sleep trackers and how they help, so you can understand your sleep better.
  

• Integrate mindfulness or meditation into your daily routine. Muse Athena has 500+ guided meditations + programs for focus, stress, and sleep, advanced data & cognitive performance tracking and ability to sync with external apps for a seamless experience.
  

• Get outside and move your body: movement helps regulate dopamine and serotonin. Even your breath can shift your brain chemistry by calming the nervous system and activating focus.
  

• Use tools like Muse to get real-time feedback on your brain’s state and train it toward calm, clarity, and recovery

Interest in hormonal health has erupted over the past year. In fact, Google Trends data shows over 7.3 million monthly searches for hormone-related topics, a staggering 193.8% year-over-year increase. That surge tells us hormones aren’t just trending; they’re fundamental to how we understand health, wellness, productivity, and even aging.

As awareness grows, the need for actionable tools becomes more apparent. With EEG + fNIRS-driven neurofeedback, Muse isn’t just riding the wave of hormone-conscious culture, it’s equipping you to measure and optimize your brain-body chemistry in real time, with clarity and confidence.

Hormones and neurotransmitters Q&A

Q: What’s the difference between hormones and neurotransmitters?

A: Hormones travel through your bloodstream and regulate long-term processes like stress, metabolism, and sleep. Neurotransmitters work within the brain and nervous system, delivering fast, moment-to-moment signals that affect your mood, motivation, and focus.

Q: Can a chemical act as both a hormone and a neurotransmitter?

A: Yes. Some chemicals, such as norepinephrine, can function as both a hormone (when released into the bloodstream by the adrenal glands) and a neurotransmitter (when released by neurons in the nervous system)

Q: What causes my brain chemistry to become imbalanced?

A: Chronic stress, poor sleep, overstimulation, nutrient deficiencies, and even lack of movement can disrupt both hormones and neurotransmitters: leading to fatigue, mood swings, or burnout.

Q: How can I naturally support my brain chemistry?

A: Start with better sleep hygiene, daily movement, mindful breathwork, and stress reduction. Tools like Muse Athena give you real-time biofeedback to help you train your brain toward calm, clarity, and recovery.

Q: Can Muse actually help me balance my brain chemistry?

A: Muse uses EEG and fNIRS to track your brain’s state and guide you through personalized neurofeedback and meditation programs that support sleep, focus, and emotional regulation.

 

 

 

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