Sleep can seem so elusive sometimes, can't it? A third of us admit to struggling with insomnia now and again, with 12% of Americans suffering from chronic insomnia over prolonged periods. (1, 2)
There's nothing worse than staring at the ceiling willing your mind and body to shut down and allow you to sleep. Or dragging yourself around the next day as if you have a great weight attached to your spine. (Hint, you do, it's called sleep deprivation).
Interest in natural sleep aids is at an all-time high, so we thought it was time to examine whether amino acids can contribute to, and possibly even improve, sleep. So let's dive in...
Introduction to Amino Acids
So what are amino acids? Simply put, amino acids are the building blocks of proteins - all protein is made up of chains or strings of amino acids. The exact combination of amino acids determines what type of protein it will be.
Think of amino acids like the letters of an alphabet. How you put the ‘letters’ together determines what the word will be. Same with amino acids and proteins.
There are 20 different amino acids and all play crucial and different roles in the body. For our purpose here today, we’ll be looking specifically at those amino acids that potentially help with sleep regulation.
But first, it’s important to understand the main types of amino acids. They are:
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Essential amino acids: The body cannot make these nine amino acids so they must be gained from food or supplements. Tryptophan - an important amino acid that we’ll discuss today - is one such essential amino acid. Others are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, and valine. There are many foods that contain tryptophan, such as beef, dairy, and eggs.
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Non-essential amino acids: The remaining 11 amino acids can be made by the body. They are aspartic acid, glutamine, alanine, cysteine, arginine, tyrosine, asparagine, glutamic acid, glycine, proline, and serine.
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Conditional amino acids: These are non-essential amino acids that become essential under certain conditions - usually illness or stress. (3)
What Do Amino Acids Do?
Amino acids have a variety of important functions in the body, including supporting cardiovascular health, promoting antioxidant defenses, and producing essential molecules like serotonin and melatonin.
Amino acids are also involved in breaking down food and repairing body tissue; providing building blocks to build muscle; strengthening the immune and digestive systems, and maintaining healthy skin, hair and nails. (4)
Some are also involved in sleep regulation….
Which Amino Acids Can Help with Sleep?
Of all the 20 amino acids, which are more likely to help with sleep regulation, sleep quality, and more? Could they even help with sleep disorders?
Possibly the most well known amino acid linked with sleep is tryptophan. This amino acid is heavily linked to serotonin and melatonin production - the all-important sleep hormone that influences our sleep-wake cycle and can affect sleep. More on that shortly.
Glycine has also been shown in small human trials to help sleep, possibly through its ability to reduce core body temperature. (5)
L-theanine, a non-protein amino acid (and just to confuse you, not one of the 20 listed above) may also help to calm the central nervous system, influence alpha brain waves, and relax the mind and body before sleep.
We're going to examine all three in more detail shortly, but first let's examine the science of sleep. We'll be talking a lot about the sleep-wake cycle, for instance, so what is it?
The Science of Sleep: The Sleep-Wake Cycle
Your sleep-wake cycle, also known as your circadian rhythm, is your body’s internal clock that keeps you in sync with the 24-hour day-night cycle.
This rhythm is regulated by the pineal gland in the brain, hormones, and various physiological processes that respond to changes in light and darkness.
The pineal gland releases melatonin in the evening as it starts to get dark. It tells the body that it's time to slow down, instructs the eyes to react less to light, and encourages blood pressure to stabilize, among other things.
Essentially, it’s a biological alarm clock that helps to prepare your body and mind for sleep, a chemical reminder to feel sleepy.
The pineal gland creates more melatonin when it’s dark, tapering off when it becomes light again, signalling the body that it is time to wake up. When your circadian rhythm is working well, it helps you feel alert during the day and sleepy at night.
Researchers continue to investigate how disruptions in melatonin production affect sleep patterns. (6)
What Can Interrupt Melatonin Production?
Unfortunately, many things can interrupt our circadian rhythms, such as:
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Age. As we age, our bodies produce less melatonin. (7)
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Jet lag and travel
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Shift work
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Alcohol or caffeine use before bed
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Certain medical conditions, or mental health conditions
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Blue light from telephones, tablets, laptops and TV screens at night
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Parenting! Constant sleep interruptions
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Poor natural light during the day, confusing the light-dark clock in our bodies
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A woman’s hormones during pregnancy, childbirth and later menopause.
For all the reasons above, you may want to consider amino acids such as tryptophan to help keep your internal body clock ticking. Let's examine its potential for sleep...
Sleep Benefits of Tryptophan
Tryptophan is an essential amino acid, meaning your body cannot produce it so it must be gained through either diet or supplements.
As well as serving as a building block for protein, tryptophan has other important roles for sleep regulation. It's a precursor for other important hormones and compounds, such as 5-HTP, serotonin and melatonin.
Tryptophan is converted to 5-HTP, which is then converted to serotonin, which is then used to make melatonin, the 'sleep hormone'. That's the simple version.
It may sound convoluted, but there are benefits to each step of the process. 5-HTP, for instance, is used by the body to increase serotonin production. Serotonin can potentially influence and improve appetite, mood, sleep, temperature, sexual behaviour and more.
As well as bringing benefits in its own right, raised serotonin levels mean there's more to convert into melatonin.
Tryptophan is converted to melatonin in the GI tract (the gut) during the day when the pineal gland in the brain isn't synthesizing it (it mostly makes melatonin at night).
Clinical Studies on Tryptophan:
Over the past 20 years, there have been more than 40 clinical trials and studies into tryptophan, assessing its impact on sleep. The weight of the studies have shown that tryptophan contributes to subjective sleepiness and reduces sleep latency (how long it takes you to fall sleep once in bed). It may also help to increase total sleep time and reduce wakefulness (how often you wake from sleep).
Results may be more pronounced in people suffering from mild insomnia and people who report a longer than normal sleep latency (ie, it takes them longer than normal to fall asleep). (8)
Tryptophan-rich foods include chicken, eggs, cheese, fish, milk, turkey, peanuts, among others.
It’s worth noting that absorption of dietary tryptophan may be hindered by the presence of other amino acids, so dietary supplements offering single amino acids, such as in Performance Lab Sleep, may offer less competition for absorption. (9)
Sleep Benefits of Glycine
Glycine is another amino acid that helps to form the protein collagen, important for your bones, skin, tendons and ligaments. Collagen production tends to decrease with age, which can impact joint and bone health.
Glycine is also often promoted as a potential support for insomnia, following three human studies that showed glycine appears to hold promise as a sleep aid.
For instance, one study of volunteers with sleep issues who were taking glycine (3g a day) concluded that it helped to improve subjective sleep quality, sleep latency, reduced how much subjects woke in the night, maintained REM sleep, and reduced daytime sleepiness.
It should be noted that the study only had 11 participants, however. (10) Other research on human studies have been similarly small.
Further studies have been carried out on animals. One such study on rats discovered that glycine helps to reduce core body temperature. (11)
Body temperature is a key player in sleep regulation. As you prepare for bed, your core body temperature naturally drops, signaling to your body that it’s time to wind down.
A cooler core body temperature is linked to better sleep quality, while a warmer body can make it harder to fall asleep or stay asleep.
The research suggests that glycine ingestion may make it easier to fall asleep and improve overall sleep quality by supporting your body’s natural cooling process. This is especially helpful for people who struggle with insomnia or have trouble staying asleep.
Other factors, such as keeping your bedroom cool and engaging in regular physical activity, can also help regulate body temperature and boost sleep efficiency.
A second study also discovered that glycine supplementation temporarily increased serotonin levels, which may help with insomnia and sleep issues. (12)
(Note in the interest of full disclosure that both of these animal studies were carried out by a company that sells glycine supplements).
Glycine has also been linked to less fatigue and improved work efficiency the day after sleep, helping you to feel refreshed in the morning. The typical glycine dosage for sleep is 3-5 grams taken orally before bed.
Higher levels of glycine supplementation may be associated with more pronounced effects, but also a greater risk of side effects. Taking too much glycine can cause side effects such as nausea, especially if the dose is not adjusted for body weight. (13, 14)
Glycine is found in high-protein foods including meat, fish, eggs, dairy, and legumes. Glycine is typically consumed through these foods as part of a regular diet. (15)
Potential Sleep Benefits of L-Theanine
Another potentially useful amino acid is l-theanine, an amino acid found in green tea. Now this is a different amino acid to the 20 we've already talked about.
L-theanine is unique in that it doesn't help to build proteins, the body cannot make it, and it is found abundantly in tea leaves, specifically in green, black and white teas. However, it does share a similar structure to the essential amino acid, glutamine. (16)
L-theanine is often used to treat stress and anxiety, hence its reputation as a natural anxiolytic - a substance that helps to calm and sedate without making you feel drowsy.
So how could it help with sleep? Simply put, because it helps to relax the central nervous system, putting you in a more relaxed state before bed.
If you want it in scientific jargon, research suggests l-theanine crosses the blood-brain barrier and influences several neurotransmitters such as GABA, serotonin production and dopamine. These help to slow brain activity, reduce anxiety and alertness, and strengthen calm, positive feelings. All beneficial before sleep.
In addition, l-theanine may also increase alpha brain waves, most prevalent in people who are drowsy and relaxed. (17)
As I mentioned, L-theanine increases the concentration of GABA in the brain. GABA is a neurotransmitter known for calming the central nervous system.
A study of mice and rats fed both l-theanine and GABA together fell asleep faster (sleep latency) and slept for longer than rodents given either l-theanine or GABA alone.
Promising research, but it should be said that human research has not yet examined the safety of taking both together. (18)
Summary: The Role of Amino Acids in Sleep
Let’s quickly recap what important roles amino acids can potentially play with sleep and sleep quality.
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Amino acids such as tryptophan and glycine may influence our sleep-wake cycles
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Tryptophan is converted into serotonin and melatonin, which are important for sleep regulation
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Glycine ingestion before bed may help lower body temperature and induce slow wave sleep.
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L-theanine may increase GABA, calm the central nervous system, and influence alpha brain waves.
Ongoing research aims to determine the precise relationship between amino acid levels and sleep quality. Out of all these, we would suggest that tryptophan is the best choice of amino acid for sleep with significant research behind it.
Best Natural Sleep Aid: Performance Lab Sleep
As we said earlier, dietary absorption of amino acids may be compromised by competition with other amino acids. If you do want to choose a dietary supplement, therefore, we'd recommend you choose one with a single amino acid.
Performance Lab Sleep fits the bill. It includes tryptophan to potentially improve the body's own 5HTP-serotonin-melatonin cycle. It contains no other amino acids, but does contain other promising natural ingredients to boost sleep.
Such as Montmorency tart cherries which give a low dose boost of melatonin naturally, along with magnesium to relax muscles and lemon balm to calm.
Please consult a healthcare provider before starting any new supplement, especially if you have underlying health conditions like sleep apnea or chronic insomnia.
Trouble Sleeping? Other Tips to Improve Sleep
As we've already discovered, amino acid levels can affect your sleep quality, so maintaining a healthy diet rich in amino acids is useful. That's not all you can do to potentially improve your sleep, however. Creating a relaxing bedtime routine can also put you in a better mood for sleep. You can do that by...
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Avoiding screens and electronic devices at least one hour before bed.
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Avoid caffeine six hours before bed.
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Avoid alcohol three hours before bed. (19)
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Get regular exercise
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Practice techniques to reduce stress
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Enjoy a balanced diet with a wide range of vitamins and minerals (and amino acids)
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Create a calming pre-bed ritual. It could be having a bath, reading a book, listening to calming music... anything to get your mind switched off, your body relaxed, and you ready for bed.
Better Sleep for Overall Health
We all know that we need sleep, and often feel terrible without it, but it’s worth taking a moment to appreciate just how crucial sleep is to our overall physical and mental health, including our immune system function and metabolism.
Poor sleep can contribute to changes in body weight and metabolism, increasing the risk of various health issues. Sleep quality can also influence the balance of fatty acids in the body, which are important for maintaining metabolic health.
For instance, sleep is important for:
Mental Health and Cognition:
When we sleep, our brains are still active. REM sleep, for instance, helps the brain to consolidate, helping to improve our memory and problem-solving skills. It also helps our brains cope and process emotions, especially fear, and helps with brain development (one reason why babies need so much sleep).
It may also help to protect against dementia. One study published in the journal Neurology found that for every 1% loss of REM sleep, the chance of dementia increases by 9%. (20)
Physical Health
As well as your brain, sleep allows your body to repair itself at night. Sleep deprivation over time, for instance, may lead to weight gain, high blood pressure, heart attack and stroke, obstructive sleep apnea, depression and anxiety, a weaker immune system, and more.
Many of these can be reversed with better sleep - plus getting more quality Zzzs can reduce the risk of workplace or car accidents, improve mood, and increase energy, motivation and attention.
The American Academy of Sleep Medicine states that as an adult, you should be getting seven hours of sleep a night or more. (21)
Final Thoughts
Out of all the above, tryptophan would seem to be the best amino acid for sleep. That’s because it has more research behind it, and more evidence suggesting it works to improve subjective sleep and sleep latency, especially for people suffering from mild insomnia.
Other studies have also found that increasing serotonin and melatonin levels can provide additional benefits for better sleep, further supporting the use of tryptophan.
It’s easy to gain tryptophan from your diet, but it may actually be better absorbed from a supplement, such as Performance Lab Sleep, where it doesn’t need to compete for absorption.
