Best Supplements for Afternoon Slump in 2026: 6 Compared

Published: November 8, 2026 · Last updated: November 8, 2026 · By NooBlue Editorial · 6 products compared · About our editorial standards

It is 2:45 pm. Lunch was an hour ago, the inbox is still full, and your eyelids feel heavier than they did at ten. Most people reach for a second or third coffee at this point. This roundup of the best supplements for afternoon slump looks at what else you can reach for, and at why the dip happens in the first place, because the right pick depends on the cause.

The afternoon slump is a real and well-described pattern. Sleep researchers call it the post-lunch dip, and it shows up even in people who skip lunch. Your body clock, the size and type of your lunch, how much you have had to drink and how well you slept all feed into it. A supplement can help with some of those causes. It cannot fix a short night or a heavy pasta lunch on its own.

We make methylene blue under the NooBlue name, so two of our own products appear here and our gummies are ranked first. We say that up front. Every competitor price was read from the brand’s own product page on November 8, 2026, and every study we cite was checked against its PubMed record the same day. Where a product’s dose differs from the dose a study used, we say so.

Best supplements for afternoon slump: our 2026 ranking

The table ranks all six products. Price per serving uses the one-time price on each brand’s own site divided by the number of servings in one pack at the label’s serving size. Subscription and bundle prices are left out so every row uses the same basis. The “latest sensible time” column is our own addition. An afternoon pick that wrecks your night just moves the slump to tomorrow.

Nootropics Depot Caffeine + L-Theanine has the lowest price per serving in this comparison at $0.33, and every row’s price was verified on the brand’s site on the same day. Cognizin is shown at both the label serving and the 500 mg daily amount used in the trial we cite, because two capsules are needed to match it.

Why the afternoon slump happens

A review in Clinics in Sports Medicine describes the post-lunch dip as a drop in some kinds of performance during the midafternoon, linked to a rise in sleep pressure at that time of day. The same paper notes that the dip can appear even when someone has had no lunch and does not know what time it is. Your body clock is the base layer. A heavy, high-carbohydrate lunch makes it worse, and people who are strongly morning types may feel it more.

On top of that base layer sit four common add-ons. Each one has a different first fix, and each one points to a different product on this list.

• A short or broken night. Sleep debt shows up most clearly at the low points of the body clock, and the early afternoon is one of them. Our guide to brain fog from lack of sleep covers how to tell when poor sleep is the real driver.
• Lunch size and makeup. A large lunch heavy in refined starch and sugar tends to deepen the dip. If you feel worst within an hour of eating, read why you get so tired after you eat before you buy anything.
• Too little to drink. In a study of 25 young women in The Journal of Nutrition, losing about 1.4% of body mass in fluid lowered concentration and vigor and raised fatigue and headache ratings.
• A long block of focused work. Mental fatigue builds across hours of sustained thinking. That is the setting where most of the ginseng, caffeine and L-theanine research on this list was done.

Light matters too, though less than you might hope. A small trial in Industrial Health exposed 20 volunteers to brighter, bluer or redder white light during the post-lunch dip. Brain-wave markers of alertness improved, but task scores and how sleepy people felt did not change. A walk outside still helps many people. Just do not expect a desk lamp to replace the basics.

Tiredness that lasts all day, every day, is a different problem from a 3 pm dip. Our guide to why you might always feel tired walks through the wider list of causes, including iron, thyroid and sleep problems that need a blood test or a doctor. See a doctor if your tiredness lasts more than a few weeks or comes with other symptoms.

Which slump is yours? Match the cause to the pick

Most lists of afternoon energy supplements skip this step. Before you choose a product, spend three workdays noting when the dip starts, what you ate, how much you drank and how you slept. Then use this table to match your pattern to a first free fix and a product.

The caffeine cut-off rule: in a home sleep study in the Journal of Clinical Sleep Medicine, 400 mg of caffeine taken even 6 hours before bed still cut total sleep time. Subtract at least 6 hours from your usual bedtime to find your last sensible caffeine time. A 10:30 pm bedtime means no caffeine after 4:30 pm, and earlier is better, because the study used a larger dose than most people take at once.

The cellular energy link: why methylene blue fits the afternoon dip

Every brain cell runs on ATP, the energy molecule made inside mitochondria. When you feel mentally flat in the afternoon, you are not literally running out of ATP, but your capacity to sustain focus does depend on how well that energy system keeps up with demand. Our explainer on what cellular energy is covers the basics.

Methylene blue interests researchers because it can accept and pass on electrons inside the mitochondrial energy chain. In human fibroblast cells grown in the lab, a study in the FASEB Journal found that low concentrations raised mitochondrial complex IV activity by 30% and cellular oxygen use by 37% to 70%. That is cell research, not a human result.

The human evidence is small but directly relevant to afternoon work. In a randomized, placebo-controlled trial published in Radiology, 26 healthy adults aged 22 to 62 took one low oral dose of methylene blue or a placebo. One hour later, brain scans showed a stronger response during a sustained-attention task and a short-term memory task, and correct answers during memory recall rose by 7%. That was a single dose in a small group, so read it as an early signal. It is also the reason we rank methylene blue first for a slump that is mostly about holding attention. For the full picture, see our guide to methylene blue for energy.

#1. NooBlue Methylene Blue Gummies: Best Overall for a Steady Afternoon Without Caffeine

NooBlue Methylene Blue Gummies take the top spot because they work on the cellular energy route and add no caffeine to your day, which matters when the slump hits at 3 pm and bedtime is only seven or eight hours away. Each gummy contains 10 mg of USP-grade methylene blue and 25 mg of vitamin C in a pectin chew with a wild blueberry flavor and zero sugar. A bottle holds 60 gummies, a 60-day supply at one a day.

Timing is where the gummy earns its place on an afternoon list. The Radiology trial measured its effects one hour after a single dose. A gummy with lunch or in the late morning therefore lines up that window with the early-afternoon dip. Follow the label directions on the bottle. Our guide to the best time to take methylene blue covers the trade-offs of morning versus midday use, and our page on methylene blue and sleep answers whether it keeps people awake.

The vitamin C has a job beyond flavor. Vitamin C can donate electrons in methylene blue’s redox chemistry, which is why we pair the two in one chew. The gummies are designed to avoid the blue-mouth mess that puts many people off liquid methylene blue, and the purple color comes from blueberry extract. No product can promise a stain-free outcome for everyone. For a balanced look at the format, read our review of whether methylene blue gummies are effective.

On testing, Contract Testing Laboratories of America (CTLA) analyzed the methylene blue ingredient, and the full Certificate of Analysis is published on the product page. That report covers the raw ingredient. It does not measure how the finished gummy is absorbed, and we make no claim that it does. Our guide to reading a methylene blue Certificate of Analysis shows what to look for on any brand’s report.

Key specs: 10 mg methylene blue USP + 25 mg vitamin C per gummy · 60 gummies · zero sugar · published CTLA Certificate of Analysis for the methylene blue ingredient · $49.99 per bottle ($0.83 per serving).

Pros:

• Works on cellular energy production, the only pick here that does
• No caffeine, so it does not eat into your caffeine cut-off
• Precisely dosed 10 mg, a standard daily amount within the low-dose range
• Third-party tested, with a published CTLA Certificate of Analysis

Cons:

• The human evidence is one small single-dose trial plus cell research
• Not suitable if you take serotonergic medicines (see the safety section)
• Costs more per serving than the caffeine and citicoline picks

Best For: healthy adults whose focus fades between 2 pm and 4 pm and who want an afternoon step that supports mitochondrial energy and focus without more caffeine.

Try NooBlue Methylene Blue Gummies →

#2. Nootropics Depot Caffeine + L-Theanine: Best if You Still Want Caffeine

Nootropics Depot Caffeine + L-Theanine is for people who are not ready to give up caffeine in the afternoon but want a smaller, more predictable dose than a large coffee. Each capsule in the standard format contains 100 mg of caffeine and 200 mg of L-theanine, the amino acid found in tea leaves. The brand also sells a second format with the ratio flipped to 200 mg of caffeine and 100 mg of L-theanine, which we would skip for afternoon use. The 60-count bottle costs $19.99 on the brand’s site, or $0.33 per capsule.

The pairing has decent short-term evidence. In a randomized, placebo-controlled crossover study in Biological Psychology, caffeine plus L-theanine improved accuracy on a demanding visual attention task, sped up simple reaction time and reduced self-rated mental fatigue. People also rated themselves as more alert and less tired. That study used 150 mg of caffeine with 250 mg of L-theanine, slightly more than one capsule here, and it measured effects over a single session.

The catch is timing. Caffeine lingers, and the home sleep study cited above found that a large dose 6 hours before bed still shortened sleep. If you go to bed at 10:30 pm, take this capsule by early afternoon at the latest and never as a 4 pm rescue. Our guide to why caffeine crashes happen explains how a late dose sets up tomorrow’s slump, and our piece on caffeine tolerance covers why the same dose seems to do less over time.

Nootropics Depot publishes batch lab-testing PDFs on the product page. Count your total caffeine for the day, including coffee, tea and energy drinks, before adding a capsule.

Key specs: 100 mg caffeine + 200 mg L-theanine per capsule · 60 capsules · batch lab reports published · $19.99 ($0.33 per serving).

Pros:

• Lowest price per serving in this comparison
• Precise dose, easier to track than coffee of unknown strength
• Human crossover trial on the caffeine and L-theanine pairing

Cons:

• Still caffeine, so late doses can cut sleep and feed the next day’s slump
• Not for people who are sensitive to caffeine or pregnant
• The study dose was slightly higher than one capsule

Best For: coffee drinkers who want a smaller, measured afternoon dose with L-theanine, taken at least 6 hours before bed.

See Caffeine + L-Theanine at Nootropics Depot

#3. Thorne Ginseng Plus: Best Herbal Pick for Long Desk Afternoons

Thorne Ginseng Plus is a three-herb capsule. A serving of two capsules provides 420 mg of Korean red ginseng extract (Panax ginseng root), 475 mg of Greek mountain tea extract and 400 mg of lion’s mane mushroom extract. The 60-capsule bottle is $48 on Thorne’s site, which works out to 30 servings at $1.60 each. The label says to take two capsules daily.

We picked it for the ginseng. In a double-blind, placebo-controlled crossover trial in the Journal of Psychopharmacology, 30 healthy young adults took a single 200 mg or 400 mg dose of a standardized Panax ginseng extract (G115), then did repeated rounds of demanding mental arithmetic and attention tests. The 200 mg dose improved one arithmetic task and reduced how mentally tired people felt across most of the rounds. Ginseng also lowered blood glucose during the test session.

Two caveats keep this at #3. The trial used a different extract from the one in this product, so the result does not transfer one for one. The product also mixes in two other herbs, which makes it harder to know which ingredient is doing the work for you. If your slump is mostly mental fatigue on long thinking tasks, it is a reasonable herbal option. If it is mostly sleepiness, the first two picks fit better. Our article on mental fatigue explains how it differs from ordinary tiredness.

Ginseng is not for everyone. Because it can lower blood glucose, check with your doctor if you take medicine that lowers blood sugar or thins the blood.

Key specs: 420 mg Korean red ginseng extract + 475 mg Greek mountain tea extract + 400 mg lion’s mane extract per 2 capsules · 30 servings · $48 ($1.60 per serving).

Pros:

• Panax ginseng has a human trial on mental fatigue during sustained work
• No caffeine, so it is fine in the early afternoon
• From a large, established supplement brand

Cons:

• The highest price per serving here
• The trial used a different ginseng extract and a single dose
• Three herbs at once make it hard to judge which one helps

Best For: people whose focus fades during long reports, study sessions or meetings, and who want a caffeine-free herbal option.

See Ginseng Plus at Thorne

#4. LMNT Zero-Sugar Electrolytes: Best if You Drink Too Little Before 3 pm

LMNT Zero-Sugar Electrolytes is a drink mix sold in single-serve sticks. Each stick contains 1,000 mg of sodium, 200 mg of potassium and 60 mg of magnesium, with no sugar. A box of 30 sticks costs $45 on the brand’s site at the one-time price, or $1.50 per stick. Most flavors were in stock when we checked.

This pick works on the most overlooked slump cause. Many office workers drink coffee in the morning, skip water through a busy lunch and reach 3 pm mildly dehydrated. The women’s study cited earlier found that about 1.4% fluid loss lowered concentration and vigor and raised fatigue and headache scores. A companion study in men in The British Journal of Nutrition found more errors on vigilance tasks and more fatigue at a similar level of fluid loss. Neither study tested LMNT itself, so this is a fluid recommendation first and a product recommendation second.

For most desk days, plain water does the job and costs nothing. LMNT earns its place on hot days, after a lunchtime workout, or if you sweat heavily. The flavor also helps some people drink more. Be careful with the sodium. At 1,000 mg per stick, it is a large dose if you have been told to limit salt, so check with your doctor first.

If your afternoon tiredness comes with feeling cold, read our guide on why you might always feel cold and tired, since fluid is only one possible factor.

Key specs: 1,000 mg sodium, 200 mg potassium, 60 mg magnesium per stick · zero sugar · 30 sticks · $45 ($1.50 per serving).

Pros:

• Works on fluid loss, a common and easy-to-miss cause
• No caffeine and no sugar, so it suits any time of day
• Simple to add to an afternoon water bottle

Cons:

• The cited studies tested fluid loss, not this product
• High sodium, which does not suit everyone
• Plain water is enough for many desk days

Best For: people who reach mid-afternoon with a still-full water bottle, a mild headache, or after a sweaty lunchtime workout.

See LMNT Zero-Sugar Electrolytes

#5. Nootropics Depot Cognizin Citicoline: Best for Memory-Heavy Afternoons Over 50

Nootropics Depot Cognizin Citicoline contains 250 mg of citicoline per capsule, using the Cognizin branded ingredient. A 60-capsule bottle costs $26.99, or $0.45 per capsule. The brand suggests taking it in the morning and publishes batch lab-testing PDFs on the product page.

Citicoline, also called CDP-choline, is a compound your body uses to build cell membranes, including those of brain cells. The best trial we found for healthy adults was published in The Journal of Nutrition. One hundred healthy adults aged 50 to 85 with mild, age-related memory complaints took 500 mg of Cognizin citicoline a day or a placebo for 12 weeks. The citicoline group improved more on episodic memory and on a combined memory score. Several of the authors work for the company that makes Cognizin, so read it as an industry-funded result.

That makes this a narrower pick than the others. It was studied over weeks, not hours, and in older adults, not in people fighting a 3 pm dip. It fits best if your afternoons are full of memory-heavy work, you are over 50 and you are willing to take it daily for a few months before judging it. Matching the study means two capsules a day, which brings the cost to $0.90. If you are weighing this against other brain products, our roundup of the best brain supplements compares more options.

Our article on the age when people start feeling tired and old covers which energy changes are normal with age and which deserve a check-up.

Key specs: 250 mg citicoline (Cognizin) per capsule · 60 capsules · batch lab reports published · $26.99 ($0.45 per serving, $0.90 at the 500 mg study amount).

Pros:

• A 12-week randomized trial in healthy older adults using this exact ingredient
• No caffeine
• Low price per capsule

Cons:

• Studied for memory over weeks, not for the afternoon dip itself
• Industry-funded trial
• Two capsules a day needed to match the studied amount

Best For: adults over 50 whose afternoon work leans on memory, who want a daily, longer-term option.

See Cognizin Citicoline at Nootropics Depot

#6. NooBlue Ultimate Methylene Blue Capsules: Best for a Gentle 5 mg Start

NooBlue Ultimate Methylene Blue Capsules hold 5 mg of USP-grade methylene blue each, half the amount in one gummy. A 60-capsule bottle is $37.99, or $0.63 per capsule. They suit people who are new to methylene blue and want to start low, or who prefer a capsule to a chew.

The 5 mg capsule is the beginner rung of the dose ladder. Many people start here for a week or two, note how their afternoons feel, and then decide whether to stay at 5 mg or move to the 10 mg gummy as their standard daily dose. Our guide to how many mg of methylene blue to take per day explains the low-dose range, and our comparison of methylene blue gummies vs capsules sets out the differences between the two formats.

The capsules contain USP-grade methylene blue and are third-party tested. At $0.63 a day, they are also the lower-cost way to try methylene blue for two weeks before committing to the gummies. If you find 5 mg is enough to steady your afternoons, there is no need to move up.

A capsule also makes it easy to keep the dose identical from day to day. That helps if you want to run the three-day slump log from earlier in this roundup and check if your 3 pm rating changes. Like the gummies, the capsules contain no caffeine.

Key specs: 5 mg methylene blue USP per capsule · 60 capsules · third-party tested · $37.99 per bottle ($0.63 per serving).

Pros:

• Low 5 mg starting dose for first-time users
• Precise, identical dose in every capsule
• No caffeine

Cons:

• The same limited human evidence as the gummies
• Same medication cautions as all methylene blue
• Some people prefer to start straight at 10 mg

Best For: first-time methylene blue users who want to start at 5 mg and judge their afternoons before stepping up.

Shop Capsules →

How we evaluated these afternoon slump supplements

We scored each product on five criteria. Because we sell two of these products, this is our ranking, not an independent one, and our gummies are placed first. Competitor facts come from each brand’s own product page on November 8, 2026, and testing claims are reported as the brands state them.

• Fit to a slump cause (30%). Each pick had to work on at least one known driver of the afternoon dip: the body clock, sleepiness, fluid loss or mental fatigue from long tasks.
• Human evidence (25%). Human trials count for more than cell research, and we say which kind each pick has. We also note when a study used a different dose or extract from the product.
• Afternoon timing (20%). A product that can be taken at 1 pm or 2 pm without cutting into sleep scored higher than one that must be taken in the morning.
• Published testing (15%). A published Certificate of Analysis, batch lab reports or another visible quality check.
• Price per serving (10%). One-time price divided by servings per pack at the label’s serving size.

We left out energy drinks and high-dose caffeine pills because they make the sleep side of the problem worse. We also left out iron and vitamin B12. Both matter for energy, but only when a blood test shows you are low, and our guide to the best supplements for fatigue already covers them. If you would rather start your day stronger than rescue the afternoon, compare this list with our morning energy roundup.

A simple 2-week plan to test an afternoon slump supplement

The fastest way to waste money on supplements is to start two at once and change your lunch the same week. This plan keeps one thing changing at a time.

1. Days 1 to 3: baseline. At 3 pm each workday, rate your energy and focus from 1 to 10. Note your sleep, lunch and how much you drank.
2. Days 4 to 5: the free fixes. Drink a full glass of water at lunch and at 2 pm, keep lunch moderate and take a short walk outside. Keep rating at 3 pm.
3. Days 6 to 14: one product. If the dip is still there, add one pick from the table at the same time each day. Keep the 3 pm rating going.
4. Day 15: decide. Compare your average 3 pm score with the baseline. A change of 2 points or more is worth keeping. Less than that, drop it and try the next pick that fits your pattern.

Citicoline is the exception. The trial ran for 12 weeks, so give it longer before you judge it. For quick ways to lift your focus on the spot, our list of fast ways to wake up your brain pairs well with this plan. If you feel exhausted and restless at the same time, read our guide to feeling wired but tired first.

Want to try methylene blue? NooBlue gummies give 10 mg with 25 mg of vitamin C and no blue mouth; the capsules give a fixed 5 mg with nothing to measure.

Get the 10 mg gummies · $49.99 Get the 5 mg capsules · $37.99

Not for use with serotonergic medicines, in G6PD deficiency, in pregnancy or breastfeeding, or under 18.

If you are weighing options, our guide to the top methylene blue supplements lines them up on grade, dose and price. Not sure where to look? Our guide on buying methylene blue in stores or online compares online, pharmacy and in-store options.

Safety: what to check before you add an afternoon supplement

The MAO-A finding comes from laboratory work on the purified human enzyme published in the British Journal of Pharmacology, which found methylene blue to be a potent MAO-A inhibitor. That is why the medication warning matters even at supplement doses. Our guides to what not to take with methylene blue and whether methylene blue is safe to take daily go into more detail.

The other picks have their own cautions. Caffeine is not suitable during pregnancy in larger amounts, and it can raise heart rate and worsen sleep in sensitive people. Ginseng can lower blood glucose and may not suit people who take blood-thinning medicine or medicine that lowers blood sugar. LMNT’s 1,000 mg of sodium per stick is a lot if you have been told to limit salt. If you want to combine methylene blue with your usual coffee, read our guide to methylene blue and caffeine first.

FAQ: supplements for the afternoon slump

What are the best supplements for afternoon slump?

NooBlue Methylene Blue Gummies are our top pick among the best supplements for afternoon slump because one precisely dosed 10 mg gummy supports mitochondrial energy and focus with no caffeine. Nootropics Depot Caffeine + L-Theanine is the best low-dose caffeine option if you take it early enough. LMNT Zero-Sugar Electrolytes suit days when too little fluid is the cause.

Why do I get so sleepy in the afternoon?

Thorne Ginseng Plus and the other picks here only help once you know the cause. The main driver is the body clock, which raises sleep pressure in the early afternoon even if you skip lunch. A large starchy lunch, too little to drink and a short night all make the dip deeper.

How do I stop getting sleepy in the afternoon without coffee?

NooBlue Methylene Blue Gummies are a caffeine-free option that supports cellular energy and focus. Pair them with the free fixes: a moderate lunch, a full glass of water at lunch and at 2 pm, and a short walk outside. If the dip is worst after short nights, an earlier bedtime will help more than any supplement.

What is a good supplement for being tired in the afternoon?

NooBlue Methylene Blue Gummies are our pick when afternoon tiredness shows up as fading focus, and LMNT Zero-Sugar Electrolytes fit days when you have drunk too little. If you feel tired all day and not only in the afternoon, ask your doctor about a blood test, since low iron or vitamin B12 needs a different approach.

What time should I stop drinking caffeine?

Nootropics Depot Caffeine + L-Theanine, like any caffeine source, belongs at least 6 hours before bed. A home sleep study found that 400 mg of caffeine taken 6 hours before bedtime still shortened total sleep. With a 10:30 pm bedtime, that means no caffeine after 4:30 pm, and earlier is better.

Does eating lunch cause the afternoon slump?

NooBlue Methylene Blue Gummies cannot undo a very heavy lunch, but lunch is only part of the story. Research on the post-lunch dip shows it appears even when people skip lunch, which points to the body clock. A large high-carbohydrate lunch makes the dip worse, so a smaller lunch built around protein and vegetables is a sensible first change.

Can I take methylene blue with caffeine?

NooBlue Methylene Blue Gummies contain no caffeine, so adding them does not change your daily caffeine total. If you want to combine methylene blue with coffee, read our guide to methylene blue and caffeine first and follow the safety rules in this roundup. Avoid methylene blue completely if you take serotonergic medicines.

When should I see a doctor about afternoon tiredness?

NooBlue products and every other supplement on this list come second to a doctor’s visit if your tiredness lasts more than a few weeks, comes with other symptoms or shows up all day. A doctor can check iron, thyroid function, blood sugar and sleep problems that no supplement will fix.

The verdict

For a steady afternoon without extra caffeine, NooBlue Methylene Blue Gummies are the clear winner among the best supplements for afternoon slump: one precisely dosed 10 mg gummy that supports mitochondrial energy and focus, a published CTLA Certificate of Analysis for the methylene blue ingredient and nothing that counts against your caffeine cut-off. If you still want caffeine, switch your third coffee for one Nootropics Depot Caffeine + L-Theanine capsule taken by early afternoon. Choose Thorne Ginseng Plus for long thinking tasks, keep LMNT for hot or sweaty days, and consider Cognizin Citicoline if you are over 50 and your work leans on memory. New to methylene blue? Start with our 5 mg capsules.

Whichever you pick, fix the free causes first and test one product at a time with a daily 3 pm rating. That habit tells you more than any label. For a wider view of the energy options we cover, compare this list with the best nootropics for energy and read why you might feel so tired after work if the slump carries into the evening.

Sources

• Monk TH. The post-lunch dip in performance. Clinics in Sports Medicine, 2005 (PMID 15892914).
• Drake C, et al. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine, 2013 (PMID 24235903).
• Armstrong LE, et al. Mild dehydration affects mood in healthy young women. The Journal of Nutrition, 2012 (PMID 22190027).
• Ganio MS, et al. Mild dehydration impairs cognitive performance and mood of men. The British Journal of Nutrition, 2011 (PMID 21736786).
• Askaripoor T, et al. Effects of light intervention on alertness and mental performance during the post-lunch dip. Industrial Health, 2019 (PMID 30369519).
• Atamna H, et al. Methylene blue delays cellular senescence and enhances key mitochondrial biochemical pathways (human IMR90 fibroblast culture). FASEB Journal, 2008 (PMID 17928358).
• Rodriguez P, et al. Multimodal randomized functional MR imaging of the effects of methylene blue in the human brain. Radiology, 2016 (PMID 27351678).
• Haskell CF, et al. The effects of L-theanine, caffeine and their combination on cognition and mood. Biological Psychology, 2008 (PMID 18006208).
• Reay JL, et al. Single doses of Panax ginseng (G115) reduce blood glucose levels and improve cognitive performance during sustained mental activity. Journal of Psychopharmacology, 2005 (PMID 15982990).
• Nakazaki E, et al. Citicoline and memory function in healthy older adults: a randomized, double-blind, placebo-controlled clinical trial. The Journal of Nutrition, 2021 (PMID 33978188).
• Ramsay RR, et al. Methylene blue and serotonin toxicity: inhibition of monoamine oxidase A (MAO A) confirms a theoretical prediction. British Journal of Pharmacology, 2007 (PMID 17721552).