Nootropics without caffeine: the science behind SIGNAL's five key ingredients
The nootropic market is full of products that promise sharper thinking but deliver little more than a caffeine hit dressed up with a long ingredients list. Stimulant-led formulations work — briefly — by forcing your nervous system into a heightened state. What follows is familiar: the jitters, the crash, the diminishing returns as tolerance builds.
SIGNAL takes a different approach. Every ingredient is chosen for a specific, evidence-backed mechanism — and none of them are stimulants. Here's what's inside, why it's there, and what the research actually says.
Zynamite® — Mango Leaf Extract (150mg per capsule)
Zynamite® is a patented extract derived from the leaves of Mangifera indica — the mango plant. Its active compound, mangiferin, has been shown to modulate neurotransmitter activity in ways that support cognitive performance, without the cardiovascular effects associated with caffeine.
In a double-blind, randomised, placebo-controlled crossover study published in Nutrients (Wightman et al., 2020), a single dose of 300mg Zynamite® significantly improved performance across a battery of cognitive tasks, with domain-specific improvements in attention accuracy and episodic memory. These benefits were observed across assessments at 30 minutes, 3 hours, and 5 hours post-dose.
Zynamite® has a clinically established onset of action at 30 minutes and a duration of approximately 5 hours — without increasing heart rate or blood pressure. It does not produce the jitters or crash characteristic of caffeine. EEG data shows that Zynamite® produces almost identical neural signatures to caffeine, but without the physiological side effects.
This is why SIGNAL is taken at 11am. The 30-minute onset means the ingredient is active before the afternoon cognitive dip arrives — not in response to it.
Cognizin® — Citicoline (125mg per capsule)
Citicoline is a naturally occurring compound that your brain produces as part of normal cell membrane synthesis. It plays a central role in brain energy metabolism and in the production of acetylcholine — a neurotransmitter closely linked to attention, learning, and memory. Production declines with age and under conditions of sustained mental demand.
Cognizin® is a patented, clinically studied form of citicoline with an established efficacy profile across multiple randomised controlled trials:
- A 28-day study in healthy adult women (McGlade et al., 2012) found significant improvements in attention performance following Cognizin® supplementation.
- A 12-week study in healthy older adults (Nakazaki et al., 2021) demonstrated improvements in episodic memory, supporting ongoing benefits for age-related cognitive maintenance.
Unlike many nootropic ingredients, the evidence base for Cognizin® is not limited to populations with cognitive impairment — it has been studied specifically in healthy adults seeking to maintain normal cognitive function.
The mechanism is cumulative: citicoline builds in the system over time. The cognitive benefits of Cognizin® deepen with consistent daily use — most users notice the clearest difference after 2–4 weeks.
TheaGreen® — L-Theanine from Green Tea (83mg per capsule)
L-Theanine is an amino acid found naturally in green tea leaves. It works by modulating key neurotransmitters — including dopamine, GABA, and glutamate — in ways that promote calm, alert focus. Unlike stimulants, it does not increase arousal or heart rate, and supports attention and working memory without the edge or anxiety that caffeine can produce.
TheaGreen® is derived from Camellia sinensis leaves and is not classified as novel under food safety regulations.
A randomised, placebo-controlled study in adults aged 50–69 (Baba et al., Journal of Medicinal Food, 2021) found that L-Theanine improved reaction time on attention tasks and increased correct responses in working memory tests.
In the context of SIGNAL, L-Theanine complements Zynamite® — delivering the calm focus that allows the sharper cognitive activation from mango leaf extract to be productive rather than anxious.
Korean Ginseng Extract (50mg per capsule)
Ginseng has been used in traditional medicine for cognitive support for centuries. Its active compounds — ginsenosides — have been the subject of significant modern research, particularly in relation to memory and neuroplasticity.
A 2024 systematic review and meta-analysis of 15 randomised controlled trials (Zeng et al., Phytotherapy Research) found that ginseng had a statistically significant positive effect on memory improvement. Ginsenosides have also been shown to enhance neuroplasticity — the brain's ability to form new connections and adapt as we learn and age.
In practical terms, ginseng in SIGNAL contributes to sustained mental energy through the afternoon window, supporting the kind of endurance that allows focus to hold across longer periods of demand.
Lion's Mane Mushroom — 12:1 Extract (62.5mg per capsule)
Lion's Mane (Hericium erinaceus) is a functional mushroom used for centuries in traditional medicine for brain health. Modern research has identified its primary mechanism: stimulation of Nerve Growth Factor (NGF), a protein that promotes the growth, maintenance, and survival of neurons — the messenger cells that underpin cognitive function.
A double-blind, parallel-groups pilot study in healthy young adults (Docherty et al., Nutrients, 2023) found that a single dose led to faster performance on an attention task at 60 minutes post-dose. The research around Lion's Mane is still emerging, but the mechanistic rationale — NGF stimulation and neuroplasticity support — is well established and the clinical evidence base is growing.
SIGNAL uses a 12:1 extract, meaning each 62.5mg delivers the equivalent of 750mg of dried mushroom. Concentration matters with Lion's Mane — many products use low-concentration forms unlikely to reach meaningful dose levels.
Why the combination matters
Each ingredient in SIGNAL targets a different aspect of cognitive function: brain energy metabolism (Cognizin®), acute mental performance and reaction time (Zynamite®), calm focused attention (L-Theanine), sustained mental energy (Ginseng), and long-term neuroplasticity (Lion's Mane). Together, they address the full picture of what happens when cognitive performance dips — not just the surface symptom.
No single ingredient does everything. The formulation is designed to work as a system.
For those looking to support physical performance alongside cognitive function, HIRO's Clean Creatine also has a meaningful evidence base for brain health, with research suggesting creatine supplementation supports cognitive processing under fatigue. And for daily hydration — which has its own documented impact on attention and working memory — HIRO Hydration Electrolytes are designed to maintain baseline electrolyte balance throughout the day.
The bottom line
SIGNAL is not a stimulant product wearing a nootropic label. It is a formulation built around five ingredients with genuine clinical evidence — patented, studied, and chosen for specific mechanisms rather than marketing appeal.
Two capsules. 11am. No caffeine. No crash.