Amino acids play a crucial role in various bodily functions, extending beyond just muscle building. Emerging research suggests that consuming specific amino acids before bed can offer a range of benefits, including improved sleep quality, enhanced muscle recovery, and optimized body composition.
The Science Behind Amino Acids and Sleep
Micronutrients, particularly amino acids, are thought to play an important role in sleep regulation and maintenance. While tryptophan is a known predictor of sleep, less is known about branched‐chain amino acids (BCAAs), which compete with tryptophan for transport across the blood-brain barrier.
L-Serine and Circadian Rhythms
L-serine is a non-essential amino acid synthesized in the body. It is also a precursor for the synthesis of other amino acids including the optical isomers D-serine and glycine as well as lipids and nucleotides and it plays a role in mediating the nutritional supply for neuroglial cells. Research indicates that l-serine may influence the circadian rhythm, the body's internal clock that regulates sleep-wake cycles. Studies suggest that ingestion of l-serine before bedtime for multiple days might attenuate the circadian phase delay in the real world and that this effect does not depend on the initial circadian phase.
One study, conducted in Japan, investigated the effects of l-serine intake before bedtime on circadian phase in real life. The subjects were 33 healthy male and female university students and they were divided into an l-serine group (n = 16) and a placebo group (n = 17). The study found that dim light melatonin onset (DLMO) after intervention was significantly delayed compared to the baseline DLMO in the placebo group (p = 0.02) but not in the l-serine group. There was a significant difference in the amount of changes in DLMO between the two groups (p = 0.04).
These findings suggest that l-serine intake before bedtime may help prevent delays in the circadian rhythm.
Read also: Explore solutions for essential amino acid deficiency
Glycine and Deep Sleep
Glycine is one of 11 amino acids synthesized naturally in the human body. Research by the Ajinomoto Group has shown that glycine, taken before bedtime, helps the body reach deep sleep more quickly. There are two types of sleep: Rapid Eye Movement (REM) sleep, which is the sleep phase when dreams tend to happen, and non-REM (NREM) sleep. The deepest stage of NREM sleep is called slow-wave sleep (SWS).
In one study, a group of subjects was given glycine before bed while another group was given a placebo. The group that took glycine reached deep sleep more quickly. In another study involving people who had reported dissatisfaction with their nightly sleep, one group of subjects was given glycine while the other group received a placebo. The level of fatigue reported by all the subjects the next morning was recorded.
BCAAs and Sleep
Branched-chain amino acids (BCAAs) are three of the amino acids that we need to get from food or supplements because our body can’t create the amounts we need. “Branched chain” refers to the unique chemical structure of these amino acids - valine, leucine, and isoleucine. BCAAs in particular are typically found in higher concentrations in animal-based foods, like chicken, dairy, and beef.
While BCAAs were significantly associated with children's sleep duration, timing and self‐reported trouble sleeping, no associations were observed in adults, in fully adjusted models.
One study examined the association between BCAAs and different sleep characteristics in a large, population‐derived sample of Australian children and their parents (mostly mothers). This study found that while BCAAs were significantly associated with sleep in children, they were not in adults. This is the first study to examine the association between BCAAs and sleep in terms of a range of actigraphy‐derived sleep parameters and self‐reported trouble sleeping.
Read also: Amino Acids and Weight Loss
Benefits of Protein and Amino Acids Before Bed
Muscle Repair, Recovery, and Growth
Consuming protein before bed provides the necessary amino acids for muscles to repair damage and grow overnight. While sleeping, the body does a lot of tissue repair work. By consuming protein, especially slow-digesting types like casein, a steady supply of amino acids is ensured to support muscle repair during sleep.
Protein synthesis must exceed protein breakdown for those looking to increase muscle mass. Consuming protein before bed can speed up muscle recovery by reducing the damage muscles endure throughout the day or after intense workouts. Night rest is crucial for overall body recovery. By including protein in your intake before bed, you promote faster regeneration of muscle fibers that were damaged during training or daily activities.
Preventing Muscle Catabolism
During sleep, the body goes several hours without nutrients. If there’s no constant supply of amino acids, the body may start breaking down muscle tissue for energy, a process called catabolism. By maintaining a stable level of amino acids in the bloodstream, casein stimulates protein synthesis throughout the night.
Supporting Fat Loss
By maintaining muscle mass during prolonged periods without food, such as at night, metabolism remains active. Nighttime protein intake is not only beneficial for those looking to gain muscle but also for those looking to improve body composition.
Improved Sleep Quality
Certain types of proteins, such as those containing tryptophan, can help improve sleep quality by promoting the production of hormones that regulate the sleep cycle, such as melatonin and serotonin.
Read also: Essential Amino Acids Guide
Types of Protein for Bedtime Consumption
Casein Protein: The Slow-Digesting Champion
The main feature of casein is its slower digestion compared to other proteins, such as whey. When consumed, casein forms a gel in the stomach, which slows its absorption in the intestines and allows a gradual and sustained release of amino acids into the bloodstream over several hours.
Casein protein not only prevents muscle breakdown but also promotes muscle recovery. By releasing amino acids throughout the night, it provides the necessary nutrients for muscles to repair damaged fibers and promote muscle growth. Therefore, casein protein is an excellent choice to consume before bed due to its slow digestion and sustained amino acid release.
Whey Protein: A Rapid Absorption Source (Not Ideal for Bedtime)
One of the main characteristics of whey protein is its rapid absorption. When consumed, whey is quickly digested and absorbed, causing a rapid increase in amino acid levels in the bloodstream.
Due to this rapid absorption, whey protein may not be the best option to consume right before bed. During the night, the body goes through a prolonged fasting period, and whey’s rapid absorption means that amino acid levels in the blood increase quickly but also drop just as fast.
Plant-Based Protein Alternatives: Soy and Pea Protein
Both soy and pea protein offer a wide range of health benefits and are particularly appealing to vegans, vegetarians, and people with food intolerances.
Soy is one of the few plant proteins that offers a complete amino acid profile. Due to its protein quality and essential amino acid content, soy protein can be useful for those looking to increase or maintain muscle mass, especially when combined with regular exercise.
Pea protein, extracted primarily from yellow peas, has become a popular alternative in protein supplements due to its nutritional profile and digestibility. Pea protein is known to be very easy to digest. It is hypoallergenic and contains no gluten or dairy, making it suitable for people with food intolerances or digestive issues. Although not a complete protein, pea protein is rich in BCAAs like leucine, isoleucine, and valine, which are important for muscle recovery and growth.
Thanks to these factors, soy and pea protein are nutritious and beneficial plant-based alternatives, ideal for vegans and people with intolerances. Soy provides a complete amino acid profile, while pea protein is notable for its easy digestion and BCAA content.
Practical Tips for Incorporating Amino Acids Before Bed
Including protein in your diet before bed is a convenient and adaptable practice.
Dosage and Timing of BCAAs
Dosage of BCAAs is quite simple - aim for about 5 grams per day. This amount is enough for those who don’t get adequate levels from their diet, but not too much for those who don’t have any trouble meeting their daily protein and amino acid needs.
Taking BCAAs before bed might not be something you’ve considered before - but it can take our muscles up to 24 hrs to recover from a workout. If you struggle to hit your daily protein needs or are trying to cut calories, BCAAs can be a great alternative to a whey or casein shake, which can feel heavier on your stomach and contribute more calories. If you’re vegetarian or vegan, taking BCAAs at night can optimise your levels for the next day.