Most people think performance is about how hard you can push. In reality, sustainable performance is determined by how well you can regulate.

Every human cell carries a clock. Every heartbeat, breath, and decision is orchestrated by the nervous system, a dynamic network that constantly adapts to both internal signals and external demands. When this system is balanced, we enter the “window of tolerance,” a zone where energy, focus, and recovery are all available. Step outside of this balance, and we veer into stress, burnout, or withdrawal.

But nervous system regulation doesn’t exist in isolation.

It is profoundly shaped by circadian rhythms, the body’s 24-hour clock that coordinates sleep, hormone release, cognitive performance, and energy availability. When circadian rhythms are aligned, the nervous system has predictable anchors: cortisol rising in the morning to promote alertness, melatonin releasing in the evening to initiate sleep, and the autonomic nervous system shifting smoothly between sympathetic and parasympathetic dominance.

When these rhythms are disrupted, through irregular sleep, late-night light exposure, shift work, or travel across time zones, the nervous system struggles to maintain balance.

This is why jet lag (both travel-induced and social jet lag) feels so destabilising: it forces the nervous system to operate out of sync with the environment, shrinking the window of tolerance and making stress harder to manage.

For high performers, this is not a trivial issue. Misaligned circadian rhythms impair focus, blunt recovery, and erode resilience. The nervous system becomes reactive instead of adaptive.

That’s why at HMN24 we connect three pillars, Circadian Modulation, Jet Lag Mitigation, and Arousal State Management, as a single, integrated system. They’re not separate problems; they’re overlapping drivers of how well the nervous system performs under pressure.

The foundation of nervous system management is learning to navigate arousal states so that we can remain resilient, productive, and healthy in a world that constantly pulls us away from balance.

The Arousal Continuum

The nervous system operates on a continuum of arousal, shifting between states of over-activation, under-activation, and optimal regulation. This continuum reflects the balance between sympathetic drive (the accelerator) and parasympathetic drive (the brake).

Hyper-arousal (Over-activation)

This is a state of sympathetic dominance, commonly known as “fight or flight.” In the short term, it sharpens awareness and mobilises energy. But when sympathetic drive remains elevated without adequate parasympathetic recovery, it leads to impaired judgement, emotional reactivity, and physical distress [1,2].

Signs include: racing thoughts, agitation, panic, anger, tight muscles, and elevated heart rate.

Common triggers: deadlines, digital overload, excessive stimulants, chaotic environments, unresolved trauma, or a lack of downtime.

Research shows that prolonged sympathetic dominance disrupts cognition, emotional regulation, and recovery capacity, predisposing individuals to burnout and stress-related illness [1,2].

Hypo-arousal (Under-activation)

At the other extreme lies parasympathetic over-dominance, a state of withdrawal where the system under-responds to external demands. Instead of balance, parasympathetic drive suppresses engagement, leaving people disconnected and depleted [3,4].

Signs include: numbness, social withdrawal, hopelessness, or dissociation.
Common triggers: sleep deprivation, nutrient deficiencies, chronic fatigue, overtraining, social isolation, or low-stimulation environments.

Left unmanaged, this collapsed state erodes motivation, cognitive performance, and resilience [3,4].

The Optimal Arousal Zone (Window of Tolerance)

Between these extremes lies the window of tolerance, a dynamic balance where sympathetic activation and parasympathetic recovery are both available. Here, the nervous system can accelerate into focus or downshift into recovery with ease.

In this zone, people experience clarity, creativity, adaptability, and stronger resilience [5–7]. The width of the window is not fixed; it expands or contracts depending on circadian alignment, recovery practices, and environmental stressors.

Those who spend more time in this zone report higher performance, improved learning, and greater adaptability under stress. Importantly, this window is not fixed. It can expand or contract depending on lifestyle, recovery practices, and environment [7].

Nervous System Management and Neurodivergence

For neurodivergent individuals, those with ADHD, autism spectrum conditions, dyslexia, or other neurological differences, the arousal continuum often presents unique challenges.

Research suggests that neurodivergence is frequently associated with heightened sensitivity to stimuli, atypical stress responses, and difficulty regulating transitions between arousal states [8,9]. For example:

• ADHD: often linked to rapid cycling between hyper- and hypo-arousal, making sustained focus difficult without external structure or supportive interventions.

• Autism: can involve heightened sensory sensitivities and a narrower window of tolerance, leading to overload in noisy or chaotic environments.

• Other neurodivergent profiles: may experience irregular sleep, circadian misalignment, or increased vulnerability to stress, further constraining nervous system flexibility.

Crucially, these are not deficits; they are differences. With the right environment and effective regulatory strategies, neurodivergent individuals often demonstrate exceptional creativity, hyperfocus, and problem-solving abilities. The challenge lies in supporting nervous system management so that these strengths can surface.

Practical applications include:

• Structuring consistent routines that reinforce circadian rhythm and reduce uncertainty.

• Creating sensory-friendly environments (light, sound, temperature) that minimise overload.

• Using movement, breathwork, or recovery rituals to widen the window of tolerance.

• Integrating tailored nutrition and supplementation strategies that support stable energy and focus.

By framing neurodivergence through the lens of nervous system regulation, organisations can move beyond deficit models and unlock the performance potential of diverse minds.

What Expands or Shrinks the Window?

Practices that expand tolerance:

• Consistent circadian rhythm and quality sleep.

• Balanced nutrition and hydration.

• Physical activity at the right intensity.

• Supportive social interactions.

• Stress management practices (breathwork, mindfulness, recovery rituals).

• Environments optimised for light, air quality, and temperature.

• Purpose-driven activity that creates engagement and flow.

Factors that constrict tolerance:

• Chronic stress without recovery.

• Overuse of stimulants (caffeine, alcohol, energy drinks).

• Irregular or insufficient sleep.

• Malnutrition or unstable blood sugar.

• Isolation and lack of social connection.

• Digital saturation, noise pollution, or unresolved trauma.

The more these constricting factors dominate, the narrower our window becomes, making us more vulnerable to stress and less able to access recovery.

Nervous System Management in Practice

This science is no longer niche. It is shaping strategies across elite sport, corporate wellness, and hospitality.

• In sport: coaches combine sympathetic drive with recovery modalities to prevent overtraining and extend careers.

• In corporate settings: organisations embed circadian management and stress regulation to reduce burnout and improve productivity.

• In hospitality: forward-thinking brands are designing biologically intelligent rooms, optimising light, air, and recovery cues to improve guest wellbeing.

On a personal level, learning to recognise your current arousal state, and knowing whether to up-regulate (for focus) or down-shift (for recovery), is one of the most powerful skills for navigating modern life.

Where HMN24 Fits

Nervous system management requires a protocol, not a pill. Light, sleep, movement, nutrition, and environment are the cornerstones. But supplementation can support these practices by providing targeted compounds that influence neurotransmitters, circadian rhythm, and recovery states.

The Role of Anxiolytic Ingredients

A central challenge of nervous system regulation is balancing stimulation with calm. Modern life often tips people into hyper-arousal, too much caffeine, too much noise, too much digital stimulation. To counter this, HMN24 formulations integrate anxiolytic ingredients compounds that reduce over-activation of the stress response without inducing sedation.

Examples include:

• L-theanine, an amino acid found in green tea, known to increase alpha brainwave activity and promote calm focus. It helps reduce the “jitter” and emotional reactivity often associated with stimulants.

• Phosphatidylserine, included in PRE-SLEEP, which blunts cortisol responses and supports transition into parasympathetic dominance.

• Palmitoylethanolamide (PEA), also in PRE-SLEEP, a lipid mediator with anti-inflammatory and calming properties that helps downshift hyperactive stress circuits.

• Ashwagandha (KSM-66®), an adaptogen with strong evidence for reducing cortisol and improving stress resilience.

These ingredients widen the window of tolerance by calming the system without flattening alertness, making them invaluable in a performance-focused nervous system protocol.

The Caffeine + L-theanine Synergy

Stimulants are a double-edged sword. While caffeine is the world’s most widely consumed performance enhancer, excessive or isolated use pushes the nervous system into hyper-arousal, racing thoughts, impaired sleep, and narrow focus.

The caffeine + L-theanine ratio is a scientifically supported strategy to mitigate this. Research suggests that pairing caffeine with L-theanine in approximately a 1:2 ratio optimises alertness while reducing the likelihood of anxiety, overstimulation, or post-stimulant crashes.

• Caffeine increases alertness by blocking adenosine receptors and promoting dopaminergic and noradrenergic activity.

• L-theanine counterbalances this by promoting GABA and serotonin activity, inducing a calm but attentive state.

Together, they improve reaction time, accuracy, and working memory, while also reducing subjective stress and jitteriness. This is the model underpinning RISE, where 125 mg of caffeine is paired with 250 mg of L-theanine, enough to enhance energy and focus in the early part of the day, without pushing the nervous system into chronic sympathetic overdrive.

The HMN24 System in Application

• RISE leverages the caffeine–L-theanine synergy to activate circadian rhythm and energy balance in the morning, providing stimulation without the overstimulation.

• FLOW sustains focus and dopaminergic tone through citicoline, NALT, and Rhodiola, extending the tolerance window for learning, problem-solving, and social engagement.

• PRE-SLEEP restores balance with anxiolytic and adaptogenic compounds like ashwagandha, phosphatidylserine, and PEA, ensuring deeper recovery and circadian stability.

• The Travel Pack integrates these phases with electrolyte and hydration strategies, supporting arousal state management and circadian alignment in high-stress environments such as travel, shift work, or demanding schedules.

Together, these formulations don’t replace the fundamentals of sleep, light, and recovery, they support them, helping individuals regulate their nervous system with more precision, balance, and resilience.

We live in a world of relentless stimulation. Coffee to start the day, screens to sustain it, alcohol to end it. The result? Nervous systems operating outside their tolerance window, stuck in cycles of over-activation or withdrawal.

The future of human performance will not be won by working harder, but by regulating better. Nervous system management is the often-overlooked foundation that enables us to thrive in high-pressure environments without breaking down, particularly when we expand this conversation to include neurodiversity.

This is why we built HMN24 as a system, to support circadian alignment, recovery, and arousal state management in daily life, travel, and performance.

If you want to see how this fits into your rhythm, explore the HMN24 system.

References

1. McGinley, M., David, S., & McCormick, D. (2015). Cortical membrane potential signature of optimal states for sensory signal detection. Neuron, 87(1), 179-192. https://doi.org/10.1016/j.neuron.2015.05.038

2. Tong, R., Kahn, U., Grafe, L., Hitti, F., Fried, N., & Corbett, B. (2023). Stress circuitry: mechanisms behind nervous and immune system communication that influence behavior. Frontiers in Psychiatry, 14. https://doi.org/10.3389/fpsyt.2023.1240783

3. Wu, K., Zhang, Y., Liu, Z., Zhou, P., & Wei, C. (2015). Coexistence and different determinants of posttraumatic stress disorder and posttraumatic growth among Chinese survivors after earthquake: role of resilience and rumination. Frontiers in Psychology, 6. https://doi.org/10.3389/fpsyg.2015.01043

4. Tian, Y., Wong, T., Li, J., & Jiang, X. (2014). Posttraumatic stress disorder and its risk factors among adolescent survivors three years after an 8.0 magnitude earthquake in China. BMC Public Health, 14(1). https://doi.org/10.1186/1471-2458-14-1073

5. Mason, E. (2012). Energy psychology and psychotherapy: a study of the use of energy psychology in psychotherapy practice. Counselling and Psychotherapy Research, 12(3), 224-232. https://doi.org/10.1080/14733145.2012.657208

6. Gautam, K., Upadhyaya, S., Pant, S., Dhungana, S., Tulachan, P., Chapagai, M., & Ojha, S. (2017). Acute stress disorder in a ten year old child following a major earthquake. Journal of Kathmandu Medical College, 5(3), 98-100. https://doi.org/10.3126/jkmc.v5i3.18423

7. Penning, S. (2014). Lifetime poly-victimization and posttraumatic stress disorder among school-going adolescents in Durban, South Africa. African Journal of Psychiatry, 17(5). https://doi.org/10.4172/psychiatry.1000133

8. Kushki, A., Drumm, E., Mobarak, M., Tanel, N., Dupuis, A., Chau, T., & Anagnostou, E. (2013). Investigating the autonomic nervous system response to anxiety in children with autism spectrum disorders. PLoS One, 8(4), e59730. https://doi.org/10.1371/journal.pone.0059730

9. Suttkus, S., Schumann, A., Cruz, F., & Bär, K. (2021). Working memory in schizophrenia: the role of the locus coeruleus and its relation to functional brain networks. Brain and Behavior, 11(5). https://doi.org/10.1002/brb3.2130