Chrono-nutrition & circadian biology
The Master Clock
Human biology follows a circadian rhythm - a roughly 24-hour cycle influencing hormones, metabolism, focus and recovery.
Every organ keeps its own rhythm, coordinated by the suprachiasmatic nucleus (SCN) — the master clock. It determines when the body is primed to perform and when it is primed to repair. Cortisol, melatonin, body temperature and insulin sensitivity all fluctuate across the day according to this rhythm. These shifts are built in. Chrono-nutrition aligns intake with this biological timing. CLKWRK is built on that principle.
Let's talk about the
Science
What is circadian rhythm?
Circadian rhythm is the body’s roughly 24-hour internal cycle that regulates sleep, metabolism, hormones, alertness and recovery.
What is the master clock in the human body?
The master clock is the suprachiasmatic nucleus, or SCN, located in the brain. It helps coordinate circadian rhythms throughout the body.
What is circadian nutrition?
Circadian nutrition is an approach to eating and supplementation that aligns intake with the body’s biological timing across the day.
Why does timing matter for supplements?
Timing matters because the body does not operate in one fixed state all day. Energy, metabolism, focus and recovery change across the day, so the timing of nutrients may influence how well they fit the body’s
needs.
Why does energy feel higher in the morning?
After waking, cortisol naturally rises and the body prepares for activity. This is one reason alertness and forward drive often feel stronger in the morning.
Why do many people feel an afternoon dip?
An afternoon dip can happen because of circadian timing, accumulated workload, meal timing and shifts in alertness across the day.
Can supplement timing affect performance?
Supplement timing may help align nutritional support with the body’s natural phases of activation, sustained output and recovery.
Why is recovery part of performance?
Performance is not just built during output. It is also built during rest, repair and overnight recovery, when the body restores capacity for the next day.
Activate
AM
Creatine Monohydrate: 3000 mg
Why It's Included
Supports high-intensity training output and strength/power when taken daily.
Sources
ISSN position stand: safety and efficacy of creatine
Source summary.
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ISSN tactical athlete position stand incl. creatine (2022
Source summary.
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Common questions & misconceptions about creatine (2024)
Source summary.
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Caffeine (from green tea): 100 mg
Rhodiola rosea extract (10:1): 300 mg
Cordyceps: 500 mg
Why It's Included
Explored in human studies for endurance/exercise tolerance markers.
Sources
Cordyceps militaris blend and high-intensity exercise tolerance (2016)
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Adaptogenic herbs incl. Cordyceps in athletic performance (2023)
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Frontiers review on fungal supplementation incl. Cordyceps (2025)
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Citicoline: 250 mg
Why It's Included
Studied for memory/attention outcomes, particularly under cognitive demand.
Sources
Citicoline and memory in healthy older adults (2021 RCT)
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Citicoline in neurodegenerative disease: review notes study quality limits (2023)
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Alzheimer’s Drug Discovery Foundation: Citicoline evidence profile
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Methylcobalamin (B12): 0.25 mg (250 mcg)
Acetyl-L-Tyrosine: 500 mg
Why It's Included
Tyrosine is studied for supporting performance under acute stress (evidence mainly for L-tyrosine).
Sources
Tyrosine and cognitive performance under stress (human study)
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N-acetyl-L-tyrosine vs L-tyrosine: pharmacokinetics (PubMed)
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Tyrosine – biochemical role overview (NCBI Bookshelf)
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Taurine: 1500 mg
Why It's Included
Studied for exercise performance and fatigue-related outcomes.
Sources
Taurine supplementation and exercise performance (meta-analysis)
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EFSA caffeine opinion mentioning taurine context in energy drinks (2015)
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Taurine in physiology and exercise (review, PubMed)
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sustain
MID
Acetyl-L-Carnitine (ALCAR): 750 mg
Why It's Included
Studied for fatigue-related outcomes and mitochondrial function in some populations.
Sources
Acetyl-L-carnitine in very old adults: fatigue/cognition (trial)
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Carnitine supplementation: fatigue-related outcomes (systematic review, PubMed)
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Carnitine – physiological role (NCBI Bookshelf)
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KSM-66® Ashwagandha: 300 mg
Alpha-lipoic acid (ALA): 100 mg
Why It's Included
Antioxidant studied in metabolic/neuropathy contexts (many trials use higher doses).
Sources
Alpha-lipoic acid: metabolic/clinical outcomes (meta-analysis, PubMed)
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Alpha-lipoic acid: biochemistry and mechanisms (NCBI Bookshelf)
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NCCIH: Alpha-lipoic acid (overview)
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Magnesium L-threonate: 500 mg
Why It's Included
Magnesium form studied for sleep-related outcomes; overall magnesium linked to sleep quality.
Sources
Magnesium supplementation and sleep outcomes (systematic review, PubMed)
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Magnesium L-threonate and sleep quality/daytime functioning (RCT, PubMed)
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NIH ODS: Magnesium fact sheet
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Acacia gum: 3000 mg
Why It's Included
Fermentable dietary fiber studied for gut tolerance and metabolic markers.
Sources
EFSA re-evaluation of acacia gum (E414) as food additive (2017)
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Acacia gum fiber tolerability/metabolic markers (Nutrients 2021)
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EFSA follow-up opinion on acacia gum data gaps (2019)
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Resveratrol: 100 mg
Why It's Included
Polyphenol studied for cardiometabolic and inflammatory markers with mixed outcomes.
Sources
Resveratrol cardiometabolic risk factors (meta-analysis, 2020)
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Resveratrol effects on inflammatory markers (systematic review/meta, 2022)
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Resveratrol and vascular health (clinical trials review, 2024)
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Creatine monohydrate: 2000 mg
Recover
PM
Glycine: 3000 mg
Magnesium glycinate: 1000 mg (compound)
Why It's Included
Magnesium supplementation is studied for sleep outcomes; most relevant when intake/status is low.
Sources
NIH ODS: Magnesium fact sheet
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Magnesium supplementation and sleep outcomes (systematic review, PubMed)
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Magnesium bisglycinate and insomnia severity (2025 RCT)
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Inositol: 1500 mg
Why It's Included
Magnesium supplementation is studied for sleep outcomes; most relevant when intake/status is low.
Sources
NIH ODS: Magnesium fact sheet
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Magnesium supplementation and sleep outcomes (systematic review, PubMed)
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Magnesium bisglycinate and insomnia severity (2025 RCT)
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Lemon balm (Melissa officinalis) 10:1: 300 mg
Apigenin extract: 50 mg
Phosphatidylserine: 200 mg
The
CLAIMS
Circadian rhythm is a 24-hour internal clock regulating more than sleep
Circadian timing system; central (SCN) and peripheral clocks
The SCN coordinates peripheral clocks across tissues and organs, regulating systemic physiology.
Sources
Finger AM et al., 2021. SCN as master clock coordinating peripheral clocks. PMC7919411; Richards J & Gumz ML, 2012. Peripheral circadian clocks and physiology. PMC3425819.
Light sets your internal clock
Light entrainment of the circadian pacemaker.
Light is the dominant zeitgeber synchronising the SCN to the external day-night cycle.
Sources
Finger AM et al., 2021. SCN entrainment by light. PMC7919411; Mieda M, 2020. Central clock and light entrainment. Neuroscience Review.
Melatonin signals biological night
Dim Light Melatonin Onset (DLMO)
DLMO is a gold-standard clinical marker for assessing circadian phase and timing shifts.
Sources
Pandi-Perumal SR et al., 2007. DLMO clinical utility. PubMed 16884842; Lewy AJ et al., 1989. Melatonin phase marker. PubMed 2706705; Cox R et al., 2024. DLMO as gold standard marker.
You metabolise food differently depending on time of day
Circadian regulation of glucose and insulin metabolism
Human studies show daily oscillations in glucose tolerance, insulin sensitivity, and energy expenditure.
Sources
Poggiogalle E et al., 2018. Circadian regulation of metabolism. PMC5995632; Henry CJ et al., 2020. Chrononutrition and metabolic health.
Circadian disruption increases cardiometabolic risk
Circadian misalignment
Misalignment between internal clocks and behaviour affects cardiovascular and metabolic pathways.
Sources
Chellappa SL et al., 2019. Circadian misalignment and cardiometabolic risk; Kelters M et al., 2025. Circadian rhythms and cardiovascular disease review.
Heart attacks and strokes show time-of-day patterns
Circadian misalignment
Circadian variation in event onset
Sources
Epidemiological data show morning peaks in myocardial infarction and stroke incidence.
Immune function follows daily rhythms
Circadian regulation of immune responses
Immune cell trafficking and inflammatory signalling oscillate across the 24-hour cycle.
Sources
Szredzka M et al., 2025. Circadian regulation of adaptive immunity; Wu Y et al., 2025. Circadian clocks and immune signalling review.
Deep sleep supports repair and growth signalling
Sleep-linked growth hormone pulses (Slow-Wave Sleep association)
Nocturnal growth hormone pulses strongly coincide with slow-wave sleep phases.
Sources
Van Cauter E et al., 1996. Sleep and growth hormone secretion. PubMed 8627466; Besedovsky L et al., 2022. Slow-wave sleep and hormonal regulation.
Sleep supports brain waste clearance
Sleep-linked growth hormone pulses (Slow-Wave Sleep association)
Evidence supports increased waste clearance during sleep and circadian influence on glymphatic flow.
Sources
Hablitz LM et al., 2020. Circadian control of glymphatic flow; Reddy OC et al., 2020. Sleep and glymphatic clearance review.
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The System
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The Core Stack
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AM · Activate
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