REM Sleep vs Deep Sleep 2026: 6 Supplements Compared

Last updated: October 15, 2026 · By Eternal Elixir Editorial

Last updated: October 15, 2026 · By Eternal Elixir Editorial · 6 products compared

REM sleep vs deep sleep comes down to two different jobs. Deep sleep is the slow, heavy stage that dominates the first half of the night and helps your body recover. REM sleep is the active, dreaming stage that grows longer towards morning and is closely tied to memory and mood. You need both, every night, and a short or broken night tends to cost you some of each.

Below we explain REM sleep vs deep sleep in plain terms, then compare six sleep supplements sold in Australia by what their human trials measured, priced in AUD per night.

A plain disclosure. Eternal Elixir makes Magnesium L-Threonate 2000mg and Saffron Extract 30mg (affron®); they are our picks, and every figure for the other four products is taken from their own labels and brand websites on October 15, 2026. For a cost-first ranking of sleep products, see our sleep supplements comparison for Australia, which this page sits beneath.

Key numbers:

• A full sleep cycle runs 80 to 100 minutes, and most adults complete four to six cycles a night (NHLBI).
• Magnesium L-threonate, 1 g a day for 21 days in 80 adults aged 35 to 55: better Oura ring deep sleep and REM sleep scores than placebo (Sleep Medicine: X, 2024).
• Valerian extract after repeated nights: slow-wave sleep began sooner than on placebo, 13.5 versus 21.3 minutes, on lab sleep recordings (Pharmacopsychiatry, 2000).
• Saffron extract (affron®), 28 days in 120 adults with unsatisfactory sleep: better sleep quality ratings and higher evening melatonin than placebo (Sleep Medicine, 2021).
• Cost per night across the six products at their label serve: $0.09 to $2.00 AUD.

REM sleep vs deep sleep: what each stage does

Sleep runs in two phases: non-REM sleep and REM (rapid eye movement) sleep. Non-REM has three stages. Stage 1 is the drift between waking and sleep, stage 2 is light but real sleep, and stage 3 is deep sleep, also called slow-wave sleep after the slow brain waves that sleep studies record during it. REM sleep follows, and the whole cycle repeats through the night.

The figures on stage timing and age come from the US National Heart, Lung, and Blood Institute’s guide to sleep phases and stages. It also notes that you get less REM sleep in a cold room, because the body does not regulate its temperature well during REM.

So which matters more? Neither stage can stand in for the other. If you sleep deeply but wake early, you cut off the late cycles where most REM sleep sits, which is why an alarm at 5 am costs more REM sleep than deep sleep.

Why the timing of your night shapes REM and deep sleep

Early cycles carry long stretches of deep sleep and short REM periods; later cycles flip the ratio. A late bedtime with a fixed alarm trims the morning cycles, so REM sleep takes the bigger hit. Our guide on how to fall asleep faster covers the bedtime habits with the best evidence, and they should come before any supplement.

Sleep trackers add a wrinkle. A ring or watch estimates stages from movement, heart rate and skin temperature, while a lab sleep study reads brain activity directly. Treat a tracker’s nightly deep sleep or REM figure as a trend line. That difference matters for the trials below, because some used a ring and some used full sleep studies.

Which supplements have trial data on deep or REM sleep?

We sorted each ingredient’s human trials by what was measured: a full sleep study (polysomnography), a consumer sleep tracker, or questionnaires and diaries. Only the first two say anything about REM sleep vs deep sleep.

Two ingredients have direct stage data: magnesium L-threonate (on a wearable) and valerian (in sleep labs). That is the main reason for the order below.

REM sleep vs deep sleep supplements: price and evidence compared

Prices are the shelf price on the date above for the smallest pack. Price per night divides that price by the nights the label serve lasts, using the upper serve where the label gives a range. A product taken as three capsules is costed on three capsules.

Eternal Elixir makes Magnesium L-Threonate 2000mg and Saffron Extract 30mg; they are our picks, and every figure for the other products is taken from their own labels and retailer pages. Glycine is the cheapest by a wide margin. Magnesium L-threonate costs the most per night and still ranks first, because it is the only product here whose ingredient improved both deep sleep and REM sleep scores against a placebo.

#1. Eternal Elixir Magnesium L-Threonate 2000mg — Best overall for deep and REM sleep

Key specs: 2,000 mg magnesium L-threonate per serve (about 144 mg elemental magnesium) · 3 capsules daily with a meal, taken in the evening for sleep · 90 vegetable capsules per bottle (30 days) · $59.99 · $2.00 per night.

Magnesium L-threonate is magnesium bound to L-threonate, a breakdown product of vitamin C. It was developed to raise magnesium levels in the brain, which is why researchers have tested it on sleep.

The key trial for this page was run by Hausenblas and colleagues at Jacksonville University and published in Sleep Medicine: X in 2024. Eighty adults aged 35 to 55 who reported sleep problems took 1 g of magnesium L-threonate or a placebo daily for 21 days, wearing an Oura ring throughout. Compared with placebo, the magnesium group recorded better deep sleep scores, better REM sleep scores and more light sleep time, and reported better mood, energy and alertness on waking.

We are clear about the limits. A ring score is an estimate, the trial lasted three weeks, and three of its authors work for AIDP, a commercial ingredient company. A second trial, run in Perth by Lopresti and Smith and published in Frontiers in Nutrition, gave 100 adults 2 g a day for six weeks and found no difference from placebo in ring-measured sleep. It did find better self-rated sleep-related impairment, plus a larger drop in heart rate and a rise in heart rate variability during sleep. So one trial supports a stage effect and one does not. Magnesium L-threonate still earns #1 because no other product on this list has a placebo-controlled result for REM sleep at all. Our magnesium L-threonate for sleep guide walks through why the two trials may differ.

The Hausenblas trial used 1 g a day; our three-capsule serve gives 2,000 mg, the Perth trial dose. If you take regular medicines, check with your GP or pharmacist first.

Pros:

• The only ingredient here with a placebo-controlled result for both deep sleep and REM sleep scores
• Label serve matches the 2 g dose of the Australian trial
• Third-party tested every batch, with the certificate of analysis sent on request

Cons:

• The dearest product per night in this list at $2.00
• The second trial found no ring-measured sleep change
• Three capsules a night, which some people find a lot to swallow

Best for: adults who wake unrefreshed and want the one supplement with direct deep and REM sleep data. Order Eternal Elixir Magnesium L-Threonate 2000mg for $59.99, 90 capsules, shipped from our Sydney warehouse. Curious how it compares with cheaper magnesium? Read magnesium L-threonate vs glycinate.

#2. Eternal Elixir Saffron Extract 30mg (affron®) — Best for a busy mind at bedtime

Key specs: 30 mg affron® saffron extract, standardised to 3.5% Lepticrosalides® · 1 capsule daily, same time each day · 90 capsules per bottle (90 days) · $49.99 · $0.56 per night.

affron® is a standardised saffron extract that Perth researchers have tested in several sleep trials, so the evidence comes from the same ingredient in our capsule.

In 2020, Lopresti, Smith, Metse and Drummond published a 28-day trial in the Journal of Clinical Sleep Medicine. Sixty-three adults with self-reported sleep problems took affron® 14 mg twice a day or a placebo. Saffron produced larger improvements in Insomnia Severity Index scores, restorative sleep scores and sleep diary quality ratings. A follow-up in Sleep Medicine in 2021 gave 120 adults 14 mg or 28 mg one hour before bed for 28 days. Both doses improved sleep quality ratings and mood on waking more than placebo, and evening melatonin rose in the saffron groups. The two doses worked about equally.

These trials did not measure sleep stages; they relied on questionnaires, diaries and saliva samples. Our article on saffron for sleep covers the full set of trials, and affron® explained covers how the extract is standardised.

Pros:

• $0.56 a night, one capsule, and a 90-day bottle
• Two placebo-controlled trials of this exact extract improved sleep quality ratings
• Evening melatonin rose in the 2021 trial, a plausible route to settling down

Cons:

• No trial of affron® has measured deep sleep or REM sleep
• Effects were measured after four weeks, so give it time
• Not for pregnancy, and check with your GP if you take mood medicines

Best for: people who lie awake replaying the day, and anyone who wants the lowest-cost Eternal Elixir option. Buy Eternal Elixir Saffron Extract 30mg for $49.99. It can sit alongside the evening magnesium L-threonate serve if you want help with both settling down and staying asleep.

#3. Swisse Ultiboost Sleep — Best for a valerian blend

Key specs: Each tablet: valerian extract 325 mg (equivalent to 1.3 g dry root), hops extract 26.67 mg, licorice, China root, Anemarrhena and magnesium 6.4 mg · 1 to 2 tablets 30 to 60 minutes before sleep · 60 tablets · $29.99 · $1.00 per night at 2 tablets ($0.50 at 1).

Valerian root has the oldest sleep-lab record of any ingredient here. In a 1994 pilot published in Pharmacopsychiatry, Schulz and colleagues recorded 14 older poor sleepers. After a week of valerian extract 405 mg three times daily, slow-wave sleep increased and stage 1 sleep decreased, while REM sleep was unchanged. A 2000 crossover study by Donath and colleagues at Humboldt University in Berlin used eight overnight recordings per person in 16 adults with confirmed sleeplessness. One dose did nothing measurable. After repeated nights, slow-wave sleep began sooner than on placebo (13.5 versus 21.3 minutes), and slow-wave sleep as a share of time in bed rose from 8.1% to 9.8% compared with baseline. REM sleep rose too, but equally under placebo.

The closest match to the Swisse formula is a valerian and hops combination tested by Füssel and colleagues in 30 adults. After two weeks of two evening tablets (each 250 mg valerian and 60 mg hops extract), people fell asleep sooner, woke less and had more slow-wave sleep. That was a small pilot, and extracts differ in strength.

Pros:

• Valerian has sleep-lab evidence for slow-wave sleep
• Flexible dose of one or two tablets
• Easy to find in Australian retailers

Cons:

• A single dose showed no effect in the best trial; it took repeated nights
• No REM sleep benefit beyond placebo in any of the three studies
• A six-herb blend makes it hard to know what is doing the work

Best for: people who want a herbal option aimed at deep sleep and will take it nightly for a few weeks. It contains licorice, so check the label if you watch your blood pressure.

#4. Bulk Nutrients Glycine — Lowest price per night in this list

Key specs: 100% glycine powder · label serve 1,000 mg once or twice daily · 250 g pouch (250 serves of 1 g) · $11.00 · $0.09 per night at 2 g.

Glycine is an amino acid the body makes and also gets from protein foods. Researchers at Ajinomoto, a Japanese amino acid manufacturer, ran the human work cited here. In a 2012 study in Frontiers in Neurology, Bannai and colleagues restricted healthy volunteers’ sleep by a quarter for three nights and gave them 3 g of glycine or placebo before bed. The glycine group reported less fatigue the next day, showed a trend towards less sleepiness and did better on a reaction-time vigilance test.

We could not verify a human trial abstract reporting glycine’s effect on deep sleep or REM sleep, so we do not claim one. The trial dose of 3 g is also above this label’s 1 to 2 g a day, so stay with the label unless your GP says otherwise.

Pros:

• $0.09 a night, by far the cheapest option compared here
• Mixes into a drink, per the label directions
• Single ingredient, nothing else in the pouch

Cons:

• No verified human data on deep or REM sleep
• The studied dose is higher than the label serve
• Small serves need micro-scales, as the brand advises

Best for: people on a tight budget who mainly want to feel less wrecked after a short night.

#5. Herbs of Gold L-Theanine 200mg — Best for a tense, wired evening

Key specs: 200 mg AlphaWave® L-theanine per capsule · 1 capsule daily with food · 30 capsules · $29.95 · $1.00 per night.

L-theanine is an amino acid found in tea leaves, better known for calm focus than for sleep. Hidese and colleagues at Japan’s National Center of Neurology and Psychiatry gave 30 healthy adults 200 mg a day or placebo for four weeks each, in random order, and reported the results in Nutrients in 2019. On L-theanine, Pittsburgh Sleep Quality Index scores improved, with lower scores for sleep latency, sleep disturbance and use of sleep medication than on placebo.

The trial dose matches this capsule, but the sleep result is self-reported and no stages were measured. The ingredient maker that supplied the tablets employs two of the authors. Our guide to supplements for stress in Australia compares L-theanine with other calming options, and supplements to lower cortisol covers the stress hormone side.

Pros:

• Label dose equals the trial dose of 200 mg
• Non-drowsy, so it also suits a stressful afternoon
• One small capsule

Cons:

• Sleep evidence is from questionnaires only
• 30 capsules is a one-month pack
• Trial size of 30 people is small

Best for: people whose sleep trouble starts with feeling keyed up after work.

#6. Swisse Ultiboost Magnesium Glycinate — Best for a standard magnesium top-up

Key specs: 150 mg elemental magnesium (from magnesium glycinate) per tablet · 1 tablet daily for general health, 2 for stress support · 60 tablets · $29.50 · $0.98 per night at 2 tablets ($0.49 at 1).

Magnesium glycinate is a gentle, well-absorbed form, and Swisse notes it is easier on the stomach than magnesium oxide. The evidence for magnesium in general comes mostly from a 2012 trial by Abbasi and colleagues, published in the Journal of Research in Medical Sciences. Forty-six older adults with long-standing sleeplessness took 500 mg of magnesium or placebo daily for eight weeks. Magnesium improved Insomnia Severity Index scores, sleep efficiency and time to fall asleep, raised blood melatonin and lowered cortisol. Total sleep time did not differ between groups.

The abstract does not name the magnesium form, and two tablets supply 300 mg, below the 500 mg used. If you are weighing forms, our guide to the types of magnesium explains how glycinate, citrate and threonate differ.

Pros:

• Two pack sizes up to 240 tablets for longer use
• Useful if your diet is low in magnesium
• Widely stocked

Cons:

• No sleep trial of this form or dose
• No deep or REM sleep data
• Formulated for muscles and stress rather than sleep specifically

Best for: older adults who want basic magnesium cover and have not tried a supplement before.

What it costs to copy each trial

What would it cost to match each trial’s length at the label serve? Today’s prices, rounded up to whole packs:

The saffron bottle stands out: one $49.99 bottle covers a full trial three times over. Magnesium L-threonate is the bigger outlay, and a six-week run is the minimum the Perth researchers tested.

How We Evaluated these sleep supplements

We compared products and did not test them on people. For REM sleep vs deep sleep support, each product was scored on five weighted criteria:

• Evidence on sleep stages (30%): placebo-controlled human data on deep sleep or REM sleep scored highest, then other measured sleep outcomes, then questionnaires alone.
• Australian availability and shipping (20%): sold by an Australian brand or retailer with local delivery.
• Price per night in AUD (20%): shelf price divided by nights at the label serve.
• Dose match (15%): how close the label serve sits to the dose used in the trial.
• Quality and transparency (15%): a clear ingredient list, a named or standardised extract, and batch testing where the brand discloses it.

Eternal Elixir batches are third-party tested, with the certificate available on request; we hold no test results for the other brands. Glycine wins on price, which is why it keeps a true “best for” label.

Habits that protect deep and REM sleep

Supplements work best on top of good sleep habits. The steps below cost nothing and protect both stages.

• Give yourself enough time in bed. Most REM sleep sits in the last cycles, so a short night cuts it first.
• Keep the same wake time all week. A steady body clock makes the order of the stages more predictable.
• Keep the bedroom comfortable rather than cold. NHLBI notes that REM sleep shortens in colder temperatures.
• See your GP if poor sleep persists. Snoring with pauses in breathing, restless legs, low mood or daytime sleepiness while driving all need a proper check. Healthdirect has a plain guide to sleep problems and when to get help.

If foggy mornings follow bad nights, our comparison of supplements for brain fog looks at the daytime side.

REM and deep sleep: frequently asked questions

Is it better to be in REM sleep or deep sleep?

REM sleep vs deep sleep is not a ranking; you need both every night. Deep sleep comes mostly in the first half of the night and is linked with physical recovery. REM sleep comes mostly in the second half and is linked with dreaming and memory.

Is 40 minutes of deep sleep per night good?

It depends on your age and on how the figure was measured. Deep sleep falls through adulthood, and some older people have very little. A ring or watch only estimates stages, so compare your own trend over several weeks and judge it by how rested you feel. Persistent tiredness is worth raising with your GP.

Is 2 hours of REM sleep good or bad?

Two hours can be normal on a full night. Each 80 to 100 minute cycle ends with a REM period, and those periods lengthen towards morning, so your total depends heavily on how long you stay asleep. A tracker’s figure is an estimate, and how rested you feel is a better guide.

Does magnesium increase deep sleep?

One form has direct data. In an 80-person trial, magnesium L-threonate at 1 g a day for 21 days improved Oura ring deep sleep and REM sleep scores compared with placebo. A second trial at 2 g a day found no ring-measured difference, so the evidence is mixed. Other forms of magnesium have no stage data.

Can a sleep tracker measure deep and REM sleep accurately?

Only approximately. Trackers estimate stages from movement, heart rate and temperature, while sleep studies read brain activity directly. Use them for trends over weeks.

How long do sleep supplements take to change your sleep?

Most trials on this page ran three to four weeks, and valerian showed no effect after a single dose. Give a product at least four weeks at the label dose before judging it.

Why do you get less deep sleep as you get older?

Slow-wave sleep peaks in early childhood, drops sharply in the teenage years and keeps falling through adulthood, according to NHLBI. Some older people have almost none. A smaller deep sleep figure on a tracker at 60 than at 30 is therefore expected, and it is the trend for you that matters.

The verdict: REM sleep vs deep sleep, and what to take

REM sleep vs deep sleep is not a contest. Deep sleep front-loads the night and REM sleep back-loads it, so the simplest way to get more of both is a longer, steadier night. Once the habits are in place, match the product to your problem:

• Best overall for deep and REM sleep: Eternal Elixir Magnesium L-Threonate 2000mg, our #1, at $2.00 a night, the only product here with placebo-controlled deep and REM sleep data.
• Busy mind at bedtime: Eternal Elixir Saffron Extract 30mg at $0.56 a night, tested in two affron® sleep trials.
• Herbal deep sleep focus: Swisse Ultiboost Sleep, with valerian’s sleep-lab record.
• Lowest spend: Bulk Nutrients Glycine at $0.09 a night.
• Keyed up after work: Herbs of Gold L-Theanine 200mg at the trial dose.

Read our magnesium L-threonate benefits guide for more. If short nights leave you flat the next day, consider Eternal Elixir Methylene Blue Capsules or the Methylene Blue Liquid 1% in the morning, and Korean Panax Ginseng 1600mg is our daytime energy option. To rank sleep products by cost instead of by stage evidence, go back to our full sleep supplements comparison.

Sources

• National Heart, Lung, and Blood Institute. Sleep Phases and Stages. nhlbi.nih.gov
• Healthdirect Australia. Sleep. healthdirect.gov.au/sleep
• Hausenblas HA, et al. Sleep Medicine: X, 2024. PMID 39252819
• Lopresti AL, Smith SJ. Frontiers in Nutrition, 2025. PMID 41601871
• Lopresti AL, et al. Journal of Clinical Sleep Medicine, 2020. PMID 32056539
• Lopresti AL, Smith SJ, Drummond PD. Sleep Medicine, 2021. PMID 34438361
• Schulz H, Stolz C, Müller J. Pharmacopsychiatry, 1994. PMID 7972346
• Donath F, et al. Pharmacopsychiatry, 2000. PMID 10761819
• Füssel A, Wolf A, Brattström A. European Journal of Medical Research, 2000. PMID 11003973
• Bannai M, et al. Frontiers in Neurology, 2012. PMID 22529837
• Hidese S, et al. Nutrients, 2019. PMID 31623400
• Abbasi B, et al. Journal of Research in Medical Sciences, 2012. PMID 23853635