Glycine in NZ: What It Is and Why People Take It for Sleep

Jessie Shi
2026-01-30T23:08:14+13:00

Glycine is a simple amino acid that many people use to support sleep routines and recovery. Here is how it works, how to take it, and what to consider for safety in NZ.

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Quick answer: Glycine is a naturally occurring amino acid found in high protein foods and in your body. In supplement form it is most often used to support sleep quality, relaxation, and general recovery, but the evidence is mixed and dose and timing matter. If you are pregnant, breastfeeding, have a medical condition, or take prescription medicines, we recommend checking with a qualified health professional before adding glycine.

What is glycine?

Glycine is the simplest amino acid. Your body uses amino acids as building blocks for proteins, and glycine is especially common in collagen, the structural protein found in skin, tendons, cartilage, and bone. Glycine also has roles in the nervous system where it acts as a signalling molecule, and it is involved in everyday processes like making creatine, bile acids, and glutathione.

You get glycine from food, and your body can also make it. A supplement may be useful when your dietary intake is low, when your routine is inconsistent, or when you want a convenient, measured amount.

Why people take glycine

Most people look at glycine for one of these reasons:

Sleep support: some studies suggest glycine taken before bed may help people feel more refreshed in the morning.

Relaxation and wind-down: glycine may support a calmer evening routine for some people, especially when paired with good sleep habits.

General protein and collagen support: because glycine is a key collagen amino acid, it is often discussed alongside collagen and gelatin rich diets.

If your main goal is sleep, you may also want to browse our Sleep collection for other options that can fit into an evening routine. If you prefer a simple, all-in-one product, Sleep Manager is another place to start.

Potential benefits, explained without hype

Glycine is popular because it is simple and usually affordable. It is also one of those ingredients where the benefits can be subtle. Instead of expecting a dramatic effect, we recommend looking for small, practical wins like falling asleep a bit faster, waking less often, or feeling slightly more switched on the next day.

Sleep quality and next-day freshness

Sleep is where glycine has the most human research interest. In several small studies, people took glycine shortly before bed and reported improvements in how rested they felt the next day. Researchers have also looked at measures like sleep onset and perceived sleep quality. Results vary, and not every study finds a clear benefit, but sleep remains the most common reason people trial glycine.

Where glycine fits best: as an add-on to habits that already support sleep, such as consistent bed and wake times, morning daylight exposure, and keeping caffeine earlier in the day.

Relaxation and evening routine support

Because glycine is involved in nervous system signalling, some people describe it as helping them feel more settled at night. This is not the same as a sedative effect, and it should not be treated as a replacement for medical care if you have persistent insomnia. Think of it as a gentle nudge that may help when your routine is already pointing in the right direction.

Collagen, connective tissue, and overall protein balance

Glycine is a major amino acid in collagen. Diets that include collagen rich foods, or collagen and gelatin products, often provide more glycine than typical lean-protein-only eating patterns. If you are focused on connective tissue support, it can be useful to zoom out and look at total protein intake, variety of protein sources, and micronutrients that also matter for tissue health.

Other areas you may see online

You will also see glycine discussed for things like blood sugar control, liver support, and exercise recovery. Some of this comes from animal or lab research, and some from small human trials. It is interesting, but not strong enough to treat as a guaranteed outcome. If those topics matter to you, the safest approach is to prioritise the fundamentals first, then use glycine as a low risk experiment with realistic expectations.

What the evidence says

Human research on glycine is still developing. The strongest interest is around sleep quality and next-day fatigue, where several small trials have found benefits at modest doses taken close to bedtime. For other areas, evidence is mixed and often depends on the population studied, the dose used, and what people are eating overall.

Our take: treat glycine as a gentle, low-friction tool. It can be worth trying for a defined period, alongside the basics that move the needle most, like consistent sleep timing, light exposure, and enough protein across the day.

How to take glycine

Common forms

Powder: typically the most flexible for dosing. It has a mildly sweet taste and mixes into water or a warm drink.

Capsules or tablets: convenient for travel and for people who do not like the taste. You may need multiple capsules to reach a study-style dose.

Typical doses used in studies

Many sleep-focused studies use around 3 grams taken before bedtime, though some people start lower to assess tolerance. Product labels vary, so always check the per serve amount and follow label directions.

Start low: consider 1 gram in the evening for several nights.

Adjust slowly: if you tolerate it well, increase gradually toward your target.

Keep it simple: try glycine on its own first so you can tell what is helping.

Track one outcome: for example, time to fall asleep, number of wake-ups, or morning alertness.

If you are unsure what is right for you, especially if you have kidney or liver concerns, a pharmacist or GP can help you choose a safe approach.

Best time of day

For sleep goals, glycine is most commonly taken 30 to 60 minutes before bed. For general use, some people split their dose between afternoon and evening. If glycine makes you feel more alert, move it earlier. If it makes you feel a little too relaxed during the day, keep it for nighttime only.

How long to try it before deciding

We suggest a simple trial: keep everything else as steady as you can, take the same dose at the same time, and reassess after 7 to 14 nights. If nothing changes, it may not be worth continuing. If you notice a small improvement, consider whether the benefit is meaningful for you, and keep using it in a way that feels sustainable.

Foods high in glycine

Glycine is found in protein foods, with higher amounts in collagen rich choices. If you eat a varied diet with enough protein, you are already getting glycine daily.

Gelatin and bone broth

Slow-cooked meat cuts with connective tissue

Fish with skin

Legumes, dairy, and eggs

A practical tip: if you are using glycine mainly for sleep, pairing it with a steady evening meal and a screen-light cut-off often makes the biggest difference.

Choosing a glycine supplement in NZ

When you are comparing options, we suggest checking these basics:

Clear label dosing: you should be able to see grams or milligrams per serve.

Simple ingredient list: fewer fillers and sweeteners makes it easier to tolerate.

Form that fits your routine: powder for flexible dosing, capsules for convenience.

Quality cues: third-party testing, GMP style manufacturing, and transparent sourcing are positives.

In New Zealand, supplements sit within a regulatory framework that is different from prescription medicines. That means you still want to be a careful label reader, and you should be cautious about bold claims. If you have questions about a product, active ingredients, or potential interactions, a pharmacist is a good first stop.

Price and value tips

Compare like-for-like doses: look at cost per gram, not just cost per bottle.

Check the serving size: some capsules provide a small amount per capsule, so you may need several.

Keep the stack simple: if you already use magnesium, L-theanine, or herbal sleep blends, add glycine one change at a time.

Safety, side effects, and interactions

Glycine is generally considered well tolerated for many adults at common supplemental doses. That said, side effects can happen, especially if you jump to a higher dose quickly.

Possible side effects

Upset stomach, soft stools, or nausea

Headache

Daytime sleepiness if taken too early or at too high a dose

Who should be cautious

Pregnant or breastfeeding people

Children

People with kidney or liver conditions

Anyone taking prescription medicines or managing a health condition

When to see a health professional

If sleep problems persist for weeks, if you have symptoms like loud snoring with daytime exhaustion, or if your mood is worsening, it is worth talking with a qualified professional. Supplements can support a routine, but they are not a substitute for diagnosis and targeted care.

If you notice new or worsening symptoms after starting glycine, stop and check in with a qualified health professional.

Glycine vs collagen, gelatin, and other options

Glycine is one piece of the collagen puzzle. If you are deciding between glycine and other products, here is a practical way to think about it:

Glycine powder: focused and flexible for dosing, often chosen for sleep routines.

Gelatin: a food-style option that provides glycine plus other amino acids, often used in cooking.

Collagen peptides: provide glycine alongside proline and hydroxyproline, and are often used for broader connective tissue support goals.

If your goal is sleep, a small, consistent bedtime dose of glycine can be the simplest test. If your goal is broader, such as supporting protein intake or connective tissue, a collagen or gelatin rich approach might fit better. Some people use both, but we suggest introducing one change at a time.

A simple 7 day glycine trial plan

If you like structure, this is an easy way to run a low-stress trial:

1. Pick your goal: for example, fall asleep faster, fewer wake-ups, or more energy in the morning.

2. Choose one bedtime routine: same wind-down time, similar screen habits, and similar caffeine cut-off.

3. Start with 1 gram: take it 30 to 60 minutes before bed for three nights.

4. Increase if needed: move to 2 to 3 grams for the remaining nights, if tolerated and label directions allow.

5. Review: decide if the change is worth keeping, and if not, drop it and try a different lever.

We also recommend keeping expectations realistic. A supplement is unlikely to compensate for major sleep disruption, shift work, or chronic stress. However, small improvements add up when your routine is consistent.

Common mistakes to avoid

Changing too many things at once: if you add glycine plus multiple other supplements, it is hard to know what helped.

Taking it at random times: consistency matters more than perfection.

Ignoring the basics: morning light, regular mealtimes, and enough protein often matter more.

Pushing the dose fast: digestive discomfort is more likely with big jumps.

FAQs

What is glycine and what does it do?

Glycine is an amino acid found in food and made by your body. It supports protein building, is common in collagen, and also plays a role in nervous system signalling.

What does glycine do in the body?

Glycine helps your body build proteins and supports processes like collagen formation, creatine production, and antioxidant pathways such as glutathione. It also acts as a neurotransmitter in the central nervous system.

What are the main benefits of glycine?

People most often use glycine to support sleep quality, relaxation, and general recovery. Evidence is strongest for sleep related outcomes in small human studies, while other potential benefits are less certain.

What dose of glycine is typical, and how do I choose a dose?

Many sleep studies use about 3 grams taken before bed. A practical approach is to start around 1 gram for a few nights, then increase gradually if you tolerate it well and your product label allows it.

What’s the best time of day to take glycine?

For sleep goals, glycine is commonly taken 30 to 60 minutes before bedtime. If you are using it for general support, you can take it later in the day, but pay attention to how it affects your alertness.

Are there side effects or downsides to glycine?

Some people experience digestive discomfort, headache, or drowsiness, especially at higher doses. If you have side effects, reduce the dose or stop and talk with a health professional.

Who should avoid glycine or check with a health professional first?

If you are pregnant, breastfeeding, have kidney or liver disease, are giving supplements to a child, or take prescription medicines, get personalised advice before using glycine.

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References

PubChem: Glycine

NCBI Bookshelf

Medsafe: Dietary supplements

New Zealand Ministry of Health: Food and nutrition