[{"data":1,"prerenderedAt":222},["ShallowReactive",2],{"supplement-l-theanine":3,"supplement-article-titles":182},{"supplement":4,"related":62},{"slug":5,"name":6,"aliases":7,"categories":10,"tagline":13,"evidenceGrade":14,"evidenceSummary":15,"dose":16,"timing":21,"mechanism":22,"description":23,"effects":24,"safety":34,"sideEffects":35,"interactions":38,"references":39,"relatedCalculators":52,"relatedArticles":55,"relatedSupplements":58,"lastVerified":61},"l-theanine","L-Theanine",[8,9],"theanine","N-ethyl-L-glutamine",[11,12],"nootropic","sleep","The amino acid in green tea that takes the edge off stress — and off caffeine — without sedation.","B","Consistent placebo-controlled trials show reduced subjective stress and improved attention when combined with caffeine. Trials are numerous but mostly small and short.",{"low":17,"high":18,"unit":19,"frequency":20},100,400,"mg","once daily; 100-200 mg alongside caffeine is the studied pairing","With your coffee for the pairing effect, or 30-60 minutes before bed for relaxation. It does not sedate, so daytime use is fine","L-theanine crosses the blood-brain barrier and increases alpha-wave activity associated with relaxed alertness. It modulates glutamate signaling and raises GABA, serotonin, and dopamine levels modestly — enough to blunt the sympathetic stress response without acting as a sedative.","L-theanine is the reason a cup of green tea feels different from a cup of coffee with the same caffeine. It is an amino acid nearly unique to tea leaves, and its signature effect is what researchers call relaxed alertness: alpha-brain-wave activity rises, subjective stress drops, and none of it comes with drowsiness or impaired performance.\n\nThe best-replicated use is the caffeine pairing. Multiple placebo-controlled trials of caffeine plus theanine — typically 100-200 mg of each — show improved attention-switching and reduced susceptibility to distraction compared with caffeine alone, alongside less jitter and a smaller blood-pressure bump. If caffeine gives you the output but also the edge, this is the cheapest fix with actual evidence behind it.\n\nOn its own, theanine’s case is solid but narrower. Randomized trials in adults under stress show reductions in subjective anxiety and stress-marker responses at 200-400 mg. The sleep evidence is thinner: theanine does not knock you out the way melatonin shifts your clock, but by quieting pre-sleep arousal it can shorten the wind-down, and small trials in adults and in children with ADHD report better subjective sleep quality.\n\nThe safety profile is about as clean as supplements get. No meaningful side effects have surfaced at studied doses, tolerance does not appear to build, and there is no withdrawal. That cleanliness is part of why it is popular — but keep the claim honest: theanine polishes the experience of being alert or winding down; it does not add horsepower on its own. Treat it as a modifier, best used to make caffeine more usable or evenings less wired.",[25,27,30],{"effect":26,"grade":14},"Improves attention when paired with caffeine",{"effect":28,"grade":14,"note":29},"Reduces subjective stress and anxiety","200-400 mg in acute-stress trials",{"effect":31,"grade":32,"note":33},"Improves sleep quality","C","via reduced pre-sleep arousal, not sedation","Exceptionally well tolerated at studied doses with no established toxicity, no tolerance build-up, and no withdrawal. Generally recognized as safe as a tea constituent consumed for centuries.",[36,37],"Occasional mild headache","Drowsiness at very high doses in sensitive users",[],[40,46],{"authors":41,"year":42,"title":43,"journal":44,"url":45},"Haskell, C. F., et al.",2008,"The effects of L-theanine, caffeine and their combination on cognition and mood","Biological Psychology","https:\u002F\u002Fdoi.org\u002F10.1016\u002Fj.biopsycho.2007.09.008",{"authors":47,"year":48,"title":49,"journal":50,"url":51},"Hidese, S., et al.",2019,"Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults: a randomized controlled trial","Nutrients","https:\u002F\u002Fdoi.org\u002F10.3390\u002Fnu11102362",[53,12,54],"caffeine-half-life","pss-10",[56,57],"caffeine-half-life-sleep","sleep-optimization",[59,60],"caffeine","melatonin","2026-08",[63,122],{"slug":59,"name":64,"aliases":65,"categories":69,"tagline":71,"evidenceGrade":72,"evidenceSummary":73,"dose":74,"timing":76,"mechanism":77,"description":78,"effects":79,"safety":90,"sideEffects":91,"interactions":96,"references":99,"relatedCalculators":118,"relatedArticles":119,"relatedSupplements":120,"lastVerified":61},"Caffeine",[66,67,68],"1,3,7-trimethylxanthine","coffee","caffeine anhydrous",[11,70],"performance","The most-used stimulant on earth, and one of the few supplements with strong evidence for both cognitive and physical performance.","A","Hundreds of trials and multiple umbrella reviews support caffeine for alertness, reaction time, and endurance performance. The effects are reliable, dose-dependent, and blunted — not erased — by habitual use.",{"low":17,"high":18,"unit":19,"frequency":75},"100-400 mg total per day; for performance, a single 3-6 mg\u002Fkg dose about 60 minutes before exercise, staying within the daily total","Morning or early afternoon. With a ~5 hour half-life, a hard cutoff 8+ hours before bed protects sleep — the caffeine half-life calculator shows your personal decay curve","Caffeine blocks adenosine receptors in the brain, suppressing the sleep-pressure signal that accumulates through the day. That antagonism raises alertness and perceived energy, and downstream effects on dopamine signaling and calcium handling in muscle contribute to its performance benefits.","Caffeine is the rare supplement that needs no introduction and still gets underestimated. Most people treat it as a habit; the research treats it as one of the most reliable ergogenic and cognitive aids ever tested. Umbrella reviews across hundreds of trials show consistent improvements in alertness, vigilance, and reaction time, plus a 2-4% improvement in endurance performance at doses of 3-6 mg per kg of body weight.\n\nThe cognitive story is mostly about restoring and defending baseline rather than raising it. Caffeine shines when you are sleep-deprived, fatigued, or mid-afternoon — states where adenosine has accumulated and there is something to block. In a fully rested brain the margin is smaller. That distinction matters for how you use it: as a tool deployed against fatigue, not a constant drip.\n\nTolerance is real but partial. Habitual users keep most of the performance benefit at the same dose, though the subjective jolt fades. What does not adapt is the half-life: roughly five hours for most adults, longer for slow CYP1A2 metabolizers and anyone on oral contraceptives. A 3 PM coffee still has half its caffeine circulating at 8 PM, which is why the highest-leverage caffeine decision is not the morning dose but the afternoon cutoff.\n\nThe safety ceiling for healthy adults sits around 400 mg per day per the major regulatory reviews, with single doses up to 200 mg considered safe. Pregnant women are advised to stay under 200 mg per day. Above the ceiling the returns invert: anxiety, tremor, heart palpitations, and wrecked sleep that quietly cancels the next day’s benefit. Pairing caffeine with L-theanine smooths the edge for people sensitive to jitters without dulling the alertness.",[80,82,85,88],{"effect":81,"grade":72},"Increases alertness and reaction time",{"effect":83,"grade":72,"note":84},"Improves endurance performance","2-4% at 3-6 mg\u002Fkg taken ~60 min before exercise",{"effect":86,"grade":14,"note":87},"Improves strength and power output","smaller and less consistent than the endurance effect",{"effect":89,"grade":72},"Raises daytime energy in sleep deprivation","Safe for healthy adults up to about 400 mg per day per EFSA and FDA reviews. It is still a stimulant: people with anxiety disorders, arrhythmias, or uncontrolled hypertension should be cautious, and pregnancy caps the advised intake at 200 mg per day.",[92,93,94,95],"Sleep disruption when taken too late","Jitteriness and anxiety at higher doses","Heart palpitations","Withdrawal headache on abrupt stopping",[97,98],"Amplifies other stimulants — do not stack with pre-workouts that already contain caffeine.","Some antibiotics (ciprofloxacin) and oral contraceptives slow caffeine clearance, effectively raising your dose.",[100,106,112],{"authors":101,"year":102,"title":103,"journal":104,"url":105},"Grgic, J., et al.",2020,"Wake up and smell the coffee: caffeine supplementation and exercise performance — an umbrella review of 21 published meta-analyses","British Journal of Sports Medicine","https:\u002F\u002Fdoi.org\u002F10.1136\u002Fbjsports-2018-100278",{"authors":107,"year":108,"title":109,"journal":110,"url":111},"McLellan, T. M., Caldwell, J. A., & Lieberman, H. R.",2016,"A review of caffeine’s effects on cognitive, physical and occupational performance","Neuroscience & Biobehavioral Reviews","https:\u002F\u002Fdoi.org\u002F10.1016\u002Fj.neubiorev.2016.09.001",{"authors":113,"year":114,"title":115,"journal":116,"url":117},"EFSA Panel on Dietetic Products, Nutrition and Allergies",2015,"Scientific Opinion on the safety of caffeine","EFSA Journal","https:\u002F\u002Fdoi.org\u002F10.2903\u002Fj.efsa.2015.4102",[53,12],[56,57],[5,121],"creatine",{"slug":60,"name":123,"aliases":124,"categories":126,"tagline":127,"evidenceGrade":14,"evidenceSummary":128,"dose":129,"timing":134,"mechanism":135,"description":136,"effects":137,"safety":148,"sideEffects":149,"interactions":153,"references":156,"relatedCalculators":175,"relatedArticles":177,"relatedSupplements":179,"lastVerified":61},"Melatonin",[125],"N-acetyl-5-methoxytryptamine",[12],"Not a sleeping pill — a clock signal. Used correctly it shifts your circadian timing; used like a sedative it mostly disappoints.","Meta-analyses confirm reduced sleep latency and strong effects on circadian problems — jet lag, shift work, delayed sleep phase. The average latency improvement in ordinary insomnia is real but modest (~7 minutes).",{"low":130,"high":131,"unit":19,"label":132,"frequency":133},0.5,5,"0.5-5 mg; 0.5-1 mg is often as effective as more","30-60 minutes before target bedtime","30-60 minutes before your target bedtime; for shifting your clock earlier, small doses several hours before bed work better than large doses at bedtime","Melatonin is the hormone your pineal gland releases as light fades, signaling circadian night to every clock-bearing tissue. Supplemental melatonin acts on MT1\u002FMT2 receptors to phase-shift that clock and modestly lower alertness — a timing signal, not a hypnotic, which is why dose timing matters more than dose size.","Melatonin is the most misunderstood popular supplement, and the misunderstanding is baked into how it is sold. It sits on the shelf next to sleep aids, gets dosed like a sleep aid, and disappoints people who expected a sleep aid — because it is not one. Melatonin is the hormone your brain uses to announce that night has arrived. Supplementing it does not sedate you; it moves the announcement.\n\nRead that way, the evidence sorts cleanly. Where the problem is timing — jet lag, shift work, the delayed sleep phase of night owls — melatonin has some of the best data in sleep medicine, with a Cochrane review finding it remarkably effective for jet lag when taken at the destination bedtime. Where the problem is garden-variety insomnia, meta-analysis finds it shaves an average of about seven minutes off sleep latency: real, but a fraction of what prescription hypnotics or CBT-I deliver.\n\nDosing is where practice diverges furthest from evidence. Receptor studies and dose-response trials point to 0.5-1 mg as sufficient — often more effective than the 5-10 mg gummies that dominate the market, which can leave morning grogginess and spillover of elevated melatonin into the next day. More timing signal is not more sleep. Equally important is the quality-control problem: analyses of retail products have found actual content ranging from a fraction of the label to several times it, so third-party-tested brands matter more here than almost anywhere.\n\nSafety at low doses and reasonable durations looks good, with grogginess and vivid dreams the common complaints, though long-term nightly use in healthy adults is less studied than the sales volume implies. The best use is surgical: shift the clock when the clock is the problem, at the smallest dose that works — and treat chronic sleeplessness as the behavioral and light-exposure problem it usually is.",[138,141,143,146],{"effect":139,"grade":72,"note":140},"Reduces jet lag","Cochrane-reviewed; take at destination bedtime",{"effect":142,"grade":14},"Shifts circadian timing (delayed sleep phase, shift work)",{"effect":144,"grade":14,"note":145},"Shortens sleep latency in insomnia","average ~7 minutes — real but modest",{"effect":147,"grade":32},"Improves sleep maintenance through the night","Low toxicity at studied doses and durations; not habit-forming. Long-term nightly use is under-studied relative to its popularity, retail product content is unreliable without third-party testing, and children’s use should involve a pediatrician.",[150,151,152],"Morning grogginess at higher doses","Vivid dreams","Headache",[154,155],"Additive with sedatives and alcohol.","Can affect anticoagulant, anticonvulsant, immunosuppressant, and blood-pressure medication — check with a pharmacist if you take any of these.",[157,163,169],{"authors":158,"year":159,"title":160,"journal":161,"url":162},"Herxheimer, A., & Petrie, K. J.",2002,"Melatonin for the prevention and treatment of jet lag","Cochrane Database of Systematic Reviews","https:\u002F\u002Fdoi.org\u002F10.1002\u002F14651858.CD001520",{"authors":164,"year":165,"title":166,"journal":167,"url":168},"Ferracioli-Oda, E., Qawasmi, A., & Bloch, M. H.",2013,"Meta-analysis: melatonin for the treatment of primary sleep disorders","PLoS ONE","https:\u002F\u002Fdoi.org\u002F10.1371\u002Fjournal.pone.0063773",{"authors":170,"year":171,"title":172,"journal":173,"url":174},"Erland, L. A., & Saxena, P. K.",2017,"Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content","Journal of Clinical Sleep Medicine","https:\u002F\u002Fdoi.org\u002F10.5664\u002Fjcsm.6462",[12,53,176],"epworth-sleepiness",[178,57,56],"using-melatonin",[5,180,181],"magnesium-threonate","ashwagandha",{"\u002Fblog\u002Fa1c-blood-sugar-guide":183,"\u002Fblog\u002Fascvd-heart-risk-guide":184,"\u002Fblog\u002Fbiological-vs-chronological-age":185,"\u002Fblog\u002Fcaffeine-half-life-sleep":186,"\u002Fblog\u002Fcalorie-deficit-guide":187,"\u002Fblog\u002Fcode-plunge-healthspan":188,"\u002Fblog\u002Fexploring-biomarkers":189,"\u002Fblog\u002Ffish-oil":190,"\u002Fblog\u002Fftp-functional-threshold-power":191,"\u002Fblog\u002Fgarmin-instinct-e-vs-instinct-3-vs-fenix-e":192,"\u002Fblog\u002Fgrip-strength-longevity":193,"\u002Fblog\u002Fheart-rate-training-zones":194,"\u002Fblog\u002Fhow-strong-am-i":195,"\u002Fblog\u002Fhydration-and-performance":196,"\u002Fblog\u002Fintermittent-fasting-evidence":197,"\u002Fblog\u002Fmagnesiumthreonate":198,"\u002Fblog\u002Fmenstrual-cycle-vital-sign":199,"\u002Fblog\u002Fmetabolic-age-explained":200,"\u002Fblog\u002Fnutrition-basics":201,"\u002Fblog\u002Foura-ring-4-vs-whoop-5":202,"\u002Fblog\u002Fpeptides-what-the-evidence-actually-shows":203,"\u002Fblog\u002Fpregnancy-weight-gain-guide":204,"\u002Fblog\u002Fprotein-for-muscle-growth":205,"\u002Fblog\u002Frace-time-prediction":206,"\u002Fblog\u002Fringconn-gen-2-vs-oura-ring-4-vs-galaxy-ring":207,"\u002Fblog\u002Fsamsung-galaxy-watch-ultra-2-vs-apple-watch-ultra-4":208,"\u002Fblog\u002Fsarcopenia-muscle-loss":209,"\u002Fblog\u002Fsleep-optimization":210,"\u002Fblog\u002Fstrength-training-fundamentals":211,"\u002Fblog\u002Funderstanding-bmr-tdee":212,"\u002Fblog\u002Funderstanding-body-composition":213,"\u002Fblog\u002Fusing-melatonin":214,"\u002Fblog\u002Fvdot-running-training":215,"\u002Fblog\u002Fvitamind":216,"\u002Fblog\u002Fvo2-max-guide":217,"\u002Fblog\u002Fwearable-health-tracking":218,"\u002Fblog\u002Fwhoop-mg-vs-whoop-5":219,"\u002Fblog\u002Fwhoop-vs-garmin-cirqa-vs-fitbit-air-vs-amazfit-helio":220,"\u002Fblog\u002Fwilks-vs-dots-powerlifting":221},"A1C: What Your Three-Month Blood Sugar Average Actually Predicts","Your 10-Year Heart Attack Risk: Making Sense of Your ASCVD Score","Biological Age vs Chronological Age: What Really Matters","Caffeine Half-Life: Why Your Afternoon Coffee Is Still Working at Midnight","Calorie Deficit 101: The Science of Sustainable Weight Loss","Cold Plunge and Healthspan: What the Evidence Actually Supports","Biomarkers: The Numbers That Actually Predict Your Health","Fish Oil and Omega-3s: What the Evidence Actually Supports","Functional Threshold Power: Why Cyclists Define Themselves by One Number","Garmin Instinct E vs Instinct 3 vs Fenix E: What Each Step Up Buys","Grip Strength: The Simplest Longevity Test in Medicine","Heart Rate Zone Training: A Complete Guide","How Strong Am I, Actually? Reading Strength Standards Honestly","Hydration and Performance: How Much Water Do You Really Need?","Intermittent Fasting: What the Research Actually Says in 2026","Magnesium Threonate: The Form That Actually Reaches Your Brain","Your Menstrual Cycle Is a Vital Sign — Here Is What to Track","Metabolic Age: What Your Smart Scale Is Actually Telling You","Nutrition Basics: Building a Solid Diet Without Overthinking It","Oura Ring 4 vs Whoop 5: Two Screenless Wearables, Two Different Philosophies","Peptides: What the Evidence Actually Shows","Pregnancy Weight Gain: The Range That Matters More Than the Number","Protein for Muscle Growth: How Much Do You Really Need?","How Fast Could You Run a Marathon? The Honest Math of Race Prediction","RingConn Gen 2 vs Oura Ring 4 vs Galaxy Ring: The Subscription Math","Galaxy Watch Ultra 2 vs Apple Watch Ultra 4: Your Phone Already Chose","Sarcopenia Starts Earlier Than You Think","Sleep Architecture: Understanding Your Sleep Cycles","Strength Training Fundamentals: Progressive Overload and One-Rep Max","BMR vs TDEE: Understanding Your Metabolism","Understanding Body Composition: Beyond the Scale","Melatonin: What It Actually Does and How to Use It Right","VDOT: Running Its Most Accurate Intensity System","Vitamin D: The Deficiency You Probably Have","VO2 Max Explained: The Gold Standard of Cardiovascular Fitness","Making Sense of Your Wearable Data: From Metrics to Action","Whoop MG vs Whoop 5.0: Is the ECG Worth $120 a Year?","Garmin Cirqa vs Amazfit Helio Strap vs Fitbit Air vs Whoop 5","Wilks vs DOTS: The Math Behind Ranking Powerlifters Fairly",1791499028792]