GABA Benefits: Dosage, Safety, Sleep, Stress, and Scientific Evidence

GABA (Gamma-Aminobutyric Acid) is an important neurotransmitter in the human body and is also widely used in food and dietary supplements. From the perspective of functional ingredients, this article sorts out its mechanism of action, human evidence, common dosages, applicable scenarios and safety boundaries.

Let’s look at the core conclusions first:

1. What exactly is GABA?

Full name:

English: gamma-aminobutyric acid (GABA); Japanese: γ-アミノ酪酸／GABA（ギャバ）

Chemical formula:

C₄H₉NO₂

Molecular weight:

103.12 g/mol.

It is not an ordinary amino acid that the body uses to make proteins;Non-protein amino acids.

What really matters is:

GABA is one of the most important inhibitory neurotransmitters in the human central nervous system.

Simple understanding:

• Glutamate → More "exciting"
• GABA → More "inhibitory"

The neural activity in the brain cannot always be in an excited state, so the GABA system is equivalent to a "brake" in the nervous system.

The human body uses glutamate throughGlutamic acid decarboxylase GADTo manufacture GABA, this process requires vitamin B6 as a cofactor. GABA can then be further metabolized by GABA transaminase and enter the energy metabolism pathway.

2. What does GABA do in the human body?

There are two main categories of receptors.

GABA-A receptor

is a ligand-gated chloride channel.

Activation usually makes it more difficult for neurons to generate action potentials, resulting in inhibition.

Many familiar sedative/anxiolytic drugs are related to the GABA-A system. For example, benzodiazepines will enhance GABA-A related signals.

GABA-B receptor

Belongs to G protein-coupled receptors.

Mainly through:

• Increase potassium ion efflux
• Reduce the entry of calcium ions
• Inhibit neurotransmitter release

further reduces neuronal excitability.

So from a physiological point of view, GABA is indeed related to:

Relaxation, anxiety, sleep, stress response, muscle tone, pain, neural excitability

are closely related.

However, one major caveat matters here.

3. GABA eaten ≠ GABA in the brain

This is the most important point to understand about GABA supplements.

GABA produced by the human body itself in the brain is very important.

However, taking 100 mg or 300 mg GABA orally cannot be simply understood as:

Because there is:

Blood brain barrier BBB

GABA itself is very hydrophilic.

Current animal experiments have different results on whether and how much it can cross the blood-brain barrier.

As of now,There is no reliable direct evidence in humans that oral administration of GABA can significantly increase GABA concentration in the brain.

Therefore, what often appears in advertisements:

is actually an oversimplification.

4. Why is oral GABA still effective?

This is also a very interesting part of the current research.

Although the problem of entering the brain has not been solved,:

GABA is indeed absorbed by the intestines.

In a human pharmacokinetic study, blood GABA increased significantly after 12 healthy subjects took 2 g of GABA.

The peak value occurs at approximately:

0.5～1.5 hours

nearby.

The average elimination half-life measured in the study is approximately:

About 5 hours.

After continuous administration of 2 g × 3 times/day for 7 days, there was no obvious accumulation.

So:

GABA definitely does not mean "it is not absorbed at all".

The real question is:

This issue has not been resolved.

5. In what ways might GABA work?

Several main hypotheses at present:

1. A small amount of GABA may cross the BBB

It does not necessarily mean "cannot enter at all".

Animal testing suggests that small amounts of transport may occur.

However, the actual amount in the human body is unclear.

2. Peripheral GABA receptors

GABA receptors are not only found in the brain.

at:

• Intestine
• Pancreas
• Peripheral nervous system
• Endocrine tissue

and other parts also exist.

Therefore, even if it does not enter the brain in large quantities, it may still have physiological effects.

3. Gut-brain axis

There is a GABAergic system in the intestine itself.

Oral administration of GABA may pass:

Gut → Vagus Nerve/Autonomic Nerve → Brain

Indirect impact:

• Pressure
• Heart rate variability
• sleep
• Emotion

This is currently one of the more reasonable explanations.

6. The most important: actual human experiment results

Let’s look at them separately according to their functions.

① Relieve stress / relax

Evidence level: ★★★☆ Moderate, there is a signal, but not strong

This is one of the directions with relatively good evidence for GABA at present.

A 2020 systematic review included 14 human studies on stress and sleep, and the conclusions reached at the time were relatively conservative:

Many studies have very small samples and widely varying experimental designs.

However, it was updated later.

2025 update system review

The researcher screened:

7 single-dose oral GABA human trials, totaling 260 subjects

Mainly allow healthy adults to:

• Arithmetic tasks
• Psychological stress tasks

Then detect:

• EEG
• HRV heart rate variability
• Salivary cortisol
• Chromogranin A
• IgA
• POMS sentiment score
• VAS fatigue/stress score

It was found that a number of objective stress indicators improved.

The study authors considered the evidence for "transient psychological distress" to be moderate to high certainty.

This is a bit more positive than the 2020 evaluation.

A typical experiment

63 adults participated in a randomized, single-blind, placebo-controlled, crossover study.

Dosage:

100 mg GABA

Take before a psychologically stressful task.

Test after 30 minutes.

The results show that the GABA group under stressful tasks:

• EEG changes are small
• Some POMS stress-related scores are better

It is suggested that 100 mg may reduce acute psychological stress response.

How to understand the realistic effect?

Don’t interpret it as:

More reasonable is:

For:

• Anxiety disorder
• Panic disorder
• Severe chronic stress
• Depression

There is currently insufficient evidence to support GABA supplementation as a treatment.

② Sleep

Evidence level: ★★★☆ Medium to low

This is the most famous use of GABA.

There is a relatively obvious pattern at present:

100 mg experiment

Some early studies suggest that people with poor sleep quality:

Take 100 mg GABA 30 minutes before bed

Continuously for about 1 week.

Found:

• Shorten the time it takes to fall asleep
• Non-REM sleep time has increased

But:

• REM
• Number of awakenings at night
• Deep sleep time
• Overall sleep efficiency

Not all indicators improved.

③ 300 mg sleep experiment

A 2018 randomized, double-blind, placebo-controlled study:

40 people with insomnia symptoms.

Among them:

• GABA: 30 people
• placebo: 10 people

Daily:

300 mg

Before going to bed:

About 1 hour

Continue:

4 weeks

Average time to fall asleep in GABA group:

13.4 minutes → 5.7 minutes

Sleep efficiency:

79.4% → 86.1%

At the same time, no serious side effects occurred.

Looks very good.

But there is a problem:

This experiment is divided into 3:1 groups, which is very small.

A later reanalysis of the systematic review noted:

Some indicators are only significant in the GABA group "before treatment vs after treatment", but are not significant when directly compared with placebo.

The change from:

cannot be attributed entirely to GABA.

This is a common problem in many health product studies.

④ 75 mg low dose sleep experiment

Another study will be conducted in 2022.

54 people were randomly divided into groups, and 50 people completed the trial.

Daily:

75 mg GABA

Continue:

4 weeks

Sleep latency:

9.0 → 4.8 minutes

At the same time:

N3 deep sleep:

8.6% → 12.9%

No GABA-related side effects were reported in the study.

But it is still a small study.

Comprehensive judgment on sleep

A more reasonable dose range:

75～300 mg

Time:

30 to 60 minutes before going to bed

Continuous:

At least 1 to 4 weeks

Might be easier to see the effect.

Most likely improvement:

Difficulty falling asleep

times possible:

Early Non-REM sleep

The evidence is poor:

• Total sleep time
• Wake up in the middle of the night
• REM
• Sleep maintenance throughout the night
• Severe chronic insomnia

The overall evaluation of the 2020 systematic review is still:

Limited sleep evidence.

A new GABA sleep system review was registered in 2025, indicating that this field continues to be re-evaluated.

⑤ Lower blood pressure

Evidence level: ★★★☆ Moderate

This effect may actually be more believable than many people realize.

The key points are:

Classic experiment

80 people:

• Normal high blood pressure
• Borderline hypertension

Subject.

Every day:

20 mg × 2 = 40 mg GABA

Continue:

12 weeks

The results showed that the systolic blood pressure of the GABA group was significantly lower than that of the placebo group.

And:

The higher the blood pressure, the more obvious the effect.

No obvious abnormal laboratory indicators or serious side effects were found.

Another experiment on 39 patients with mild hypertension used GABA-containing fermented milk.

Continue:

12 weeks

Blood pressure in the GABA group began to decrease after 2 to 4 weeks.

Average compared to baseline after 12 weeks:

SBP:

−17.4 mmHg

DBP:

−7.2 mmHg

However, only the significant difference was achieved between SBP and placebo, so it cannot be directly understood that GABA itself caused the 17 mmHg decrease.

What Japanese data show

A GABA functional food system evaluation published by the Japan Consumer Agency concluded that:

Every day:

12.3～120 mg GABA

In some studies, it can be reduced:

• Normal high blood pressure
• High blood pressure
• Degree 1 hypertension

However, it has no obvious antihypertensive effect on people with normal blood pressure.

This is why Japanese supermarkets often carry products labeled:

It is not completely unfounded.

But it cannot be used as an antihypertensive drug

Some studies on GABA-containing foods appear to be very effective, but they:

• The number of people is small
• Food matrix is different
• There is fermented milk
• There is soy sauce
• There is chlorella
• Has other ingredients

Therefore, it is difficult to completely attribute the effect to GABA.

For example, a Cochrane analysis of fermented milk as a whole found:

The average SBP improvement is only about:

−2.45 mmHg

There was no significant change in DBP, and the evidence was considered insufficient to treat this food as a treatment for hypertension.

Therefore the actual evaluation should be:

⑥ Memory

Evidence level: ★☆☆☆ Very weak/Currently not supported

This is very important.

Many products will be affected by:

To further publicize:

But the logic does not hold.

A very direct human experiment was published in 2023.

32 healthy young adults.

Randomized, double-blind, placebo-controlled, crossover experiment.

Doses even up to:

800 mg GABA

About 45 minutes after taking:

• Working memory
• Spatial attention
• Time attention

Test.

Result:

Working memory has not improved.

Time attention has not improved.

Search accuracy has not improved.

Instead:

Visual search reaction time slows down.

Therefore there is currently no evidence to support:

⑦ Concentration/Attention

Evidence level: ★☆☆☆

There is also a lack of evidence.

The previous 800 mg experiment even found:

Visual search speed reduced.

This is actually in line with its positioning of "suppression and relaxation".

So:

If a person is overly nervous and under great pressure,

GABA may reduce tensionIndirectly makes people feel more focused.

However:

Strictly speaking, there is currently no evidence that it is a cognitive enhancer.

⑧ Anxiety

This is also often misunderstood.

Because many anti-anxiety drugs in prescription drugs involve the GABA system, some people think:

Not so.

Benzodiazepines act on GABA-A receptors in the brain.

Whether orally administered GABA enters the brain tissue in large amounts is still a question.

Therefore:

For short-term mild psychological stress: There is evidence.

For clinical anxiety disorders: Insufficient evidence.

The two must be separated.

⑨ Emotion

Some small studies found:

• POMS fatigue
• Vitality
• Subjective pressure

Possible improvements.

But the results are inconsistent.

The 2025 systematic review also pointed out:

The results of objective stress biomarkers are relatively consistent,

But:

Subjective POMS/VAS score changes were significantly more unstable.

That is to say:

⑩ Growth hormone GH

This is a rather peculiar function of GABA.

A study gave 11 men with resistance training experience:

3 g GABA

Randomized, double-blind, placebo crossover trial.

Result:

The GH peak value increases approximately in the resting state:

~400%

GABA also further enhances GH response after exercise.

Sounds very exaggerated.

But special attention should be paid here:

GH itself fluctuates greatly.

One hormone peak cannot directly equal the long-term muscle gain effect.

⑪ Muscle gain

There is a rather interesting little experiment.

21 men completed 12 weeks of training.

A group:

10 g whey protein

Another group:

10 g whey + 100 mg GABA

Results Whole body lean body mass increased:

Whey group:

Approx. +146 g

GABA+whey group:

Approx. +1,340 g

The difference is significant.

However:

There was no significant difference between groups in arm + leg lean body mass.

And there were only 21 people in the study.

There are also researchers related to GABA production companies involved in the study.

So:

There is a research signal.

But far less than:

To this extent.

Another experiment in 2025 with 26 obese women used:

200 mg/day + exercise for 12 weeks

Some body composition and exercise indicators also improved, but there were no differences between groups in many major indicators.

Therefore, it is still exploratory evidence.

⑫ Insulin/blood sugar

2 g GABA human pharmacokinetics study found a very interesting phenomenon.

GABA uses:

Fasting insulin:

About:

1.6 times

Approximately after repeated use:

2 times

Also increases fasting glucagon.

However:

Blood sugar has not changed significantly.

GABA is abundant in animal studies:

• β cells
• Diabetes
• Insulin

Related experiments.

However, it cannot be concluded from this at present:

Human clinical evidence is far from sufficient.

⑬ Fat loss

Currently:

No reliable evidence.

Theoretically:

GABA → GH ↑ → Fat metabolism ↑

This kind of reasoning is common.

However, there are no high-quality, large-scale human experiments to prove that ordinary people taking GABA for a long time can significantly reduce fat.

So if the product is promoted:

The level of evidence is very low.

⑭ Pain

Theoretically, the GABA system is related to pain regulation.

And many neuropathic pain drugs are related to the GABA-related system.

But this does not mean that oral GABA supplements can treat pain.

There is even research being done on:

500 mg/day × 4 weeks

Exploratory trial targeting pain and sleep.

The evidence is insufficient.

7. Actual research doses corresponding to different efficacy

can be organized into this table:

8. Reasonable dosage for ordinary people to use in practice

If the purpose is only:

Relaxation/Stress

50～100 mg

In anticipation of a stressful event:

30～60 minutes

Use.

sleep

A safer approach is:

Starting: 75～100 mg

Before going to bed:

30～60 minutes

Continuous:

1 to 2 weeks

Observe.

If the effect is not obvious:

200~300 mg can be considered.

But there is currently no strong evidence that:

There is no evidence:

9. Is the more GABA the better?

No.

This is a very important point.

Most of the general functional research focuses on:

20～300 mg

Common products are labeled:

• 500 mg
• 750 mg
• 1,000 mg
• 3,000 mg

These higher doses do not mean greater effects.

Actually:

The dose-effect relationship is not well established at all.

10. Absorption speed

After oral administration:

~30 minutes

Blood GABA may be significantly elevated.

Part of the research:

reaches the peak value in 30 to 90 minutes.

2 g in human pharmacokinetic study:

Tmax is about:

1～1.5 hours

Average half-life:

~5 hours.

Sleep studies therefore typically have subjects:

Take 30 to 60 minutes before going to bed.

This has certain pharmacokinetic basis.

11. On an empty stomach or after a meal?

There is currently no high-quality evidence that:

There are two methods of human research.

So the actual usage is more important:

Time is stable.

If GABA causes stomach discomfort:

It is more reasonable after a meal.

for sleep:

It can be done anywhere from 30 to 60 minutes after dinner to before going to bed.

12. Safety

In this regard, GABA performs well overall.

USP - The United States Pharmacopoeia Commission has conducted a relatively comprehensive safety evaluation of GABA.

The conclusion is:

No clear serious safety risks have been identified so far.

In human research:

120 mg/day × 12 weeks

No serious side effects occurred.

Even very high:

18 g/day × 4 days

No serious toxicities were reported.

However:

Please do not interpret this as:

These high-dose experiments:

• The number of people is small
• Time is short

Therefore, it can only prove that no obvious serious problems were found in the short term.

13. Possible side effects

reported in human experiments:

• Drowsiness
• Headache
• Abdominal discomfort
• Dizziness
• Burning sensation in throat
• Skin stinging/burning sensation
• Temporary breathing discomfort

Majority:

Mild and short-lived.

300 mg Sleep Study Rio:

Adverse events were reported by 10% of subjects.

includes:

• Abdominal discomfort
• Headache
• Drowsiness, etc.

14. Why does high dose cause throat irritation?

at:

5～10 g

In even higher dose studies, some people showed:

• Throat burning
• Skin tingling

usually disappears after a few minutes.

The probability of this problem is much lower with normal doses of 50 to 300 mg.

15. People with low blood pressure should pay special attention

This is one of the most real interaction risks of GABA.

Because some studies show:

GABA lowers blood pressure.

The USP specifically states:

If used simultaneously:

Antihypertensive drugs

It is theoretically possible to increase:

Risk of hypotension.

Especially since:

• Hypotension
• Orthostatic hypotension
• Easily dizzy

people, be cautious.

16. What about taking it with sleeping pills?

High-quality interaction experiments are lacking here.

But from the perspective of pharmacological logic:

If used simultaneously:

• Benzodiazepines
• Z-drug
• Sedating antihistamines
• Barbiturates
• Alcohol
• Other strong sedative ingredients

should be cautious.

Because it may increase:

Drowsiness/reduced reaction speed.

However, it cannot be said that GABA has exactly the same mechanism as these drugs, because the extent to which oral GABA enters the brain itself has not been determined.

17. Pregnant/lactating period

It is not recommended to supplement by yourself.

The reason is not that it has been proven harmful.

Instead:

There is insufficient human safety information.

USP's safety assessment also clearly states the lack of pregnancy and lactation data.

18. Children

Likewise:

Insufficient long-term supplementary data.

Adult supplement doses cannot be simply converted to children based on body weight.

19. Is there "GABA deficiency"?

For ordinary healthy people:

There is no "GABA nutritional deficiency" like vitamin C deficiency.

The human body can produce GABA by itself.

Therefore:

Neither:

RDA / Japanese dietary intake standard recommended amount

Such a concept.

So the more accurate concept of taking GABA is:

Functional supplement

instead of:

"Supplement the GABA that the human body lacks."

20. Is there GABA in food?

Yes.

Exists in many plants and fermented foods, such as:

• Germinated brown rice
• Brown rice
• Tea
• Tomato
• Potato
• Soybeans
• Fermented food
• Lactic acid bacteria fermentation products

Especially:

Fermentation

and:

Germination

can increase GABA content.

For example, some studies report that the GABA in ordinary rice/brown rice is only about a few to tens of mg/100 g, but it can be significantly increased through fermentation.

21. Is there a difference between "natural GABA" and "synthetic GABA"?

Chemical GABA molecule:

are essentially the same molecule.

What is called in the market:

• Natural GABA
• Fermented GABA
• GABA
• PharmaGABA

The main differences are usually:

Production methods and raw material sources

For example, use:

Lactobacillus

Ferment glutamate to produce GABA.

Is fermenting GABA necessarily more effective?

There is currently no reliable evidence.

Many human studies do use fermented GABA.

But no high-quality large-scale:

Head-to-head experiment.

So:

"Natural/fermented" does not automatically equal "better medicinal efficacy".

This is more about product positioning.

22. What is PharmaGABA?

This is one of the commercial fermented GABA raw materials.

Many GABA studies use similar fermentation sources.

But be careful:

The core active substance is still:

γ-aminobutyric acid.

The advantages of brand raw materials may be:

• Manufacturing standards
• Purity
• Raw material consistency
• Supported by specific research

rather than a completely different pharmacological ingredient.

23. How about GABA + L-Theanine?

This is a very common combination:

GABA → inhibition/relaxation

L-Theanine → Relaxing but relatively less sedative

Animal experiments show that the two may have a synergistic sleep effect.

However, high-quality evidence of "combination vs. GABA alone" in humans is still limited.

So:

Theoretically sound.

Clinical evidence remains limited.

Combining the two is a reasonable formulation choice, although evidence for added benefit remains limited.

Twenty-four, GABA + magnesium

is also a common combination.

The logic is also valid:

Magnesium is involved in the regulation of neural excitability.

But:

There are no strong human RCTs demonstrating that GABA+magnesium is significantly better than GABA alone.

Therefore, it is more of a reasonable combination than a proven synergistic combination.

Twenty-five, GABA + Vitamin B6

This one is slightly different.

Glutamic acid decarboxylase that produces GABA in the human body:

Requires vitamin B6 as a cofactor.

However:

If there is no shortage of B6 in the first place,

A large amount of extra B6 does not mean:

So also:

The physiological mechanism is established ≠ The supplementation effect must be obvious.

26. Why does Japan like GABA so much?

Japan can be said to be:

One of the most mature markets for GABA functional foods in the world.

Common products:

• Chocolate
• Coffee
• Tea
• Drinks
• Candy
• Sleep supplement
• Blood pressure supplement

Under Japan’s Foods with Function Claims system, companies may file scientifically supported claims such as:

"Helps lower blood pressure in people whose blood pressure is slightly elevated"

and:

"Helps relieve temporary psychological stress"

among other functions.

There are indeed products using GABA as a functional ingredient in the Consumer Affairs Agency database.

However, there is another issue that is easily misunderstood.

27. Foods with Function Claims do not equal government-certified efficacy

This distinction is important.

Japan’s Consumer Affairs Agency explains that:

Foods with Function Claims

are supported and submitted by companies based on scientific evidence.

Companies are responsible for the claims they file.

The Consumer Affairs Agency:

does not approve the efficacy of each product as it does for Foods for Specified Health Uses (FOSHU).

Therefore:

cannot be translated into:

More accurately:

28. What is the safe upper limit of GABA?

Currently there is no globally unified:

UL (Tolerable Upper Intake Level)

That is to say:

Not officially recognized:

Some Canadian product guidance compiled by USP mentioned:

50～3000 mg/day

No more than:

750 mg

If:

≥300 mg/day for more than 4 weeks

It is recommended to consult a medical professional.

But this number:

is not the "optimal effective dose".

Nor:

Nor does it mean that 3,000 mg works best.

29. A more reasonable long-term dose

If a healthy adult is only for:

Stress + Relaxation

Based on the existing evidence:

50～100 mg/day

Already consistent with existing research.

If:

Difficulty falling asleep

Can:

Starting from 75～100 mg

If there is no obvious effect, consider again:

200～300 mg.

Products should not be labeled solely because they are:

just think that the product is more advanced.

Thirty. How long does it take for it to take effect?

Different purposes.

Acute relaxation/stress

About:

30～60 minutes

Some experiments are designed this way.

sleep

That night:

Maybe someone can feel it.

But the more reliable sleep studies generally last:

1 to 4 weeks.

Blood pressure

Usually it is not meaningful to eat it once.

Research in general:

Changes begin to appear in 2 to 4 weeks

Continue:

8 to 12 weeks.

Muscle gain

Of course at least:

Weeks to months + resistance training.

31. Will tolerance develop?

Currently:

There are insufficient long-term human studies.

Unlike benzodiazepines, which have been very clear:

• Tolerance
• Dependency
• Withdrawal

Evidence.

Short-term human PK studies have also not seen significant GABA accumulation.

But long term:

6 months, 1 year, several years

High-quality safety/tolerability data are very limited.

Therefore, the available evidence cannot establish that:

can only say:

32. Will it be addictive?

There is currently no evidence that common GABA food supplements have typical addictive properties.

It is the same as:

• Benzodiazepine
• GHB

Not the same thing.

Especially not because of similar names:

GABA

and:

GHB (γ-hydroxybutyrate)

Confused.

They are different substances.

33. The strength of the evidence for GABA, the overall ranking of the strength of the evidence

Thirty-four, GABA’s biggest marketing misunderstanding

There are five main ones.

Misunderstanding 1:

"GABA is an important neurotransmitter in the brain, so eating GABA can definitely nourish the brain."

Wrong.

The blood-brain barrier is the biggest problem.

Misunderstanding 2:

"GABA can improve memory and concentration."

There is currently no reliable human evidence.

800 mg human experiment still did not improve working memory.

Misunderstanding 3:

"The higher the dose, the better."

No evidence.

Misunderstanding 4:

"Promote GH, so it can obviously increase muscle, reduce fat and resist aging."

The inference goes far beyond the available evidence.

Misunderstanding 5:

"Japanese functionally indicated food = Japanese government certification is valid."

Wrong.

It belongs to the corporate responsibility declaration system rather than the government's efficacy approval of product-by-product.

35. Is GABA worth trying?

If a healthy adult goal is:

For someone whose mind will not switch off at night, with mild tension and difficulty falling asleep

Based on the available evidence, GABA:

Worth trying as a low-risk experimental ingredient.

Available from:

75～100 mg, 30～60 minutes before going to bed

Start.

Its biggest advantage is:

• Relatively safe
• Small dose
• Not a prescription sedative
• There are certain human experiments
• There are many Japanese products

But don't expect:

If the target is:

"Improve learning, memory, and work concentration"

The conclusion is completely different:

GABA is not a priority.

Because direct human trials have so far shown no improvement:

• Working memory
• Time attention
• Visual search accuracy

Even 800 mg slowed down the visual search response.

That is to say:

Finally give GABA an actual score

Combining the scientific rationale, practical effects, safety profile, and amount of research:

One sentence summary:

In the ingredient classification of "improving cognition, memory, and concentration", GABA is more suitable to be classified into the category of "providing indirect assistance by improving stress and sleep status" rather than a direct cognitive enhancer.