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In today’s fast-paced, stressed-out world it can be a real challenge to consistently get a good night’s sleep. And whilst statistics vary widely, it is estimated that somewhere around a third of adults in Western countries experience sleep problems at least once a week according to the National Institute for Health and Care Excellence (NICE).1

Lack of sleep can affect almost every aspect of health, from energy levels, mood, stress resilience, memory and cognition to immune function and the ability to achieve / maintain a healthy weight. And if sleepless nights persist and become the norm, they can be a significant factor underlying common chronic health problems too.

Whilst we know that being sleep-deprived is bad news for your immediate and longer-term health and wellbeing, the great news is there’s lots you can do to support a better night’s rest. In this article we shine a gentle night light on the relaxing and restful power of glycine - an important natural compound that has impressive science-backed potential to support your sleep. And why it makes the perfect sleep partner, when paired with magnesium.

What is glycine?

Glycine is both an amino acid and a neurotransmitter. It is a ‘non-essential’ amino acid – this means that given the right ingredients, your body can produce glycine. You also consume glycine in your diet via protein foods such as meat, eggs, fish, dairy and legumes.2 In fact, the richest food sources of glycine are the cuts of meat that are often discarded such as animal tendons, cartilage, skin, bones and bone marrow. Bone broth and gelatin are rich sources of dietary glycine, but it can also be taken in food supplement form.

Why do we need glycine?

Glycine is widely considered to be one of the most important amino acids for the body and thus we have high requirements for it. Around 11.5% of the total amino acid content in the human body is represented by glycine and approximately 20% of the total amino acid nitrogen in body proteins is from glycine.

Around 80% of the the body’s glycine is used for protein synthesis, being used to make a number of important protein structures including collagen. In fact, around one third of collagen is composed of glycine, which is needed for making and repairing connective tissue, for muscle growth and repair, and for maintaining and healing the lining of the GI tract.

Glycine is needed by the body for the production of glutathione – the body’s master antioxidant – and has antioxidant, anti-inflammatory and immuno-modulatory effects. In fact, glycine is recognised as rate-limiting for glutathione synthesis and supplemental glycine has been reported to increase tissue glutathione levels in animal studies. It is also a precursor for creatine – an important compound used by the muscles and brain for energy. RNA, DNA and haem are also generated by several pathways involving glycine.3

This amazing amino acid also has a vitally important role to play as a neurotransmitter in both peripheral and central nervous systems, and has been found to support restful sleep.

Research shows glycine supports quality sleep

In a 2007 study published in Sleep and Biological Rhythms, researchers investigated the effects of glycine ingestion before bedtime on subjective sleep quality in human volunteers who have been continuously experiencing unsatisfactory sleep. The researchers concluded:

“Glycine improved subjective sleep quality and sleep efficacy (sleep time / in-bed time), and shortened PSG latency both to sleep onset and to slow wave sleep without changes in the sleep architecture. Glycine lessened daytime sleepiness and improved performance of memory recognition tasks.”4

So how does glycine support sleep?

Blood brain barrier
It can cross the blood brain barrier (BBB). Exogenous glycine passively diffuses across the BBB and modulates neurotransmission in the central nervous system (CNS).

Neurotransmitter
It has a crucial role to play not just as an amino acid but has important neurotransmitter activity too, including calming effects as a main inhibitory neurotransmitter in the central nervous system.5

Body temperature
Sleep and body temperature are closely linked and you are likely blissfully unaware that before you drift off to sleep you will experience a decrease in your core body temperature. One of the ways that glycine has been found to impact sleep is via its actions on reducing core body temperature. In a 2007 study, glycine administration before bedtime decreased core body temperature in human subjects.6

Circadian Rhythm
It also appears to have a positive influence on sleep via circadian rhythm modulation. And whilst its mode of activity in this area is not yet completely understood, researchers have postulated that glycine influences both thermoregulation (body temperature) and circadian organisation via modulation of NMDA receptors in the suprachismatic nucleus (SCN) – our 24hr body clock - and also via its close relationship with the neuropeptide arginine vasopressin (AVP).7

Magnesium & glycine - perfect sleep partners

Dubbed “nature’s tranquilizer”, magnesium is well known for its relaxing, sleep-supportive properties, but what is less well known is that these qualities are also shared by glycine – making them perfect partners for supporting your sleep. When you take magnesium in supplement form it’s usually attached to something else to help it pass more easily through the gut wall and into the bloodstream. Magnesium glycinate is no different – it is simply magnesium attached to two molecules of glycine. And when you take magnesium in this restful form, not only do you get the relaxing benefits of magnesium, you get significant benefits from glycine too – a real win-win.

Magnesium glycinate; the ideal magnesium supplement to harness the benefits of both magnesium and glycine to support your sleep.


Find Out More:

READ: For a range of simple yet effective, sleep-supportive diet and lifestyle tips, take a look at our ‘how to sleep well’ infographic.
READ: 5 Ways Magnesium Supports Your Sleep
READ: Confused About The Different Forms Of Magnesium


References:
1. https://cks.nice.org.uk/topics/insomnia/background-information/prevalence/
2. Abdul Razak M, Shajahan Begum, P, et al. Multifarious beneficial effect of nonessential amino acid glycine: a review. Oxid Med Cell Longev. 2017; 1716701.
3. McCarty MF, O’Keefe JH, DiNicolantonio JJ. Dietary glycine is rate-limiting for glutathione synthesis and may have broad potential for health protection. Ochsner J. 2018 Spring; 18(1): 81-87.
4. Yamadera W, Inagawa K, et al. Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep and Biological Rhythms. Volume 5, Issue 2. April 2007. Pages 126-131.
5. Lopez-Corcuera B, Benito-Munoz C, et al. Glycine transporters in glia cells: structural studies. Adv Neurobiol. 2017; 16:13-32
6. Nagao K, Bannai M, Kawai N, Endo T.2007. Glycine decreases core body temperature in healthy volunteer Jap Soc Sleep Res The 32nd Annual Meeting of Japanese Society of Sleep Research: 1-S-017.
7. Kawai N, Sakai N et al. The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus, Neuropsychopharmacology 40(6) (2015) 1405-16.

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