Short answer: nitric oxide (NO) is one of the signals your brain uses to build the drive for deep sleep. It also widens blood vessels in your hands and feet so your core temperature can drop for sleep, and it keeps your metabolism working smoothly overnight. As we age, NO production falls — and deep sleep falls with it. Poor metabolic health speeds up both.
Key takeaways
- Nitric oxide helps build "sleep pressure" in the brain, the drive that pulls us into deep, restorative sleep.
- NO-driven blood flow to the hands and feet helps the body shed heat — one of the triggers for falling asleep.
- By around 40, most adults make roughly half the nitric oxide they did at 20. Deep sleep declines over the same years.
- Blood sugar, insulin and abdominal fat affect NO, and poor sleep worsens all three. Sleep, NO and metabolism form one connected system.
- Daily habits support NO at any age, and Ultimate 4 supports both of the body's NO pathways in one daily scoop.
What is nitric oxide?
Nitric oxide is a gas your body makes in tiny amounts, used as a signalling molecule. It's best known for relaxing blood vessels and supporting healthy circulation. But NO is also made by nerve cells in the brain, where it helps regulate sleep, memory and the nervous system.
Your body makes NO in two ways: from the amino acid arginine (via enzymes called NOS), and from dietary nitrate in vegetables such as beetroot, rocket and spinach, which mouth bacteria help convert.
How does nitric oxide help us sleep?
Research points to three ways NO supports normal sleep.
1. It builds the drive for deep sleep
The longer we're awake, the more "sleep pressure" builds in the brain. A key signal in that process is adenosine, which accumulates through the day and helps push us into deep, slow-wave sleep at night.
Nitric oxide sits upstream of this. Studies show that NO production rises in a sleep-regulating area of the brain (the basal forebrain) during extended waking, and that this NO triggers adenosine release. When researchers blocked NO in this area, the normal rebound of deep sleep after sleep loss didn't happen. In simple terms, NO helps tell the brain it's time to sleep deeply.
NO-producing neurons in the brainstem are also involved in switching on REM sleep, the dreaming stage linked to emotional processing and memory. A review in Sleep Medicine Reviews identified NO as an important regulator of both slow-wave and REM sleep.
2. It helps cool the body for sleep
To fall asleep, your core body temperature needs to drop. The body does this by opening blood vessels in the hands and feet so heat can escape. Researchers found that warm hands and feet are one of the best predictors of how quickly people fall asleep.
Nitric oxide is one of the main molecules that relaxes and opens blood vessels. Healthy NO-driven circulation helps the body release heat at night, which supports faster sleep onset.
3. It helps calm inflammation and stress
Healthy NO signalling from the lining of the blood vessels helps keep inflammation and oxidative stress in balance. That matters because ongoing inflammation disrupts restorative sleep, and poor sleep in turn increases inflammation.
One nuance: large bursts of NO produced during inflammation (by an enzyme called iNOS) behave very differently from the small, steady signals of healthy NO. The goal is balanced, healthy NO signalling, not simply more.
Why do we sleep worse as we get older?
Sleep changes long before old age. Deep sleep starts declining in our twenties and thirties. In a well-known study of healthy men, deep sleep fell from close to a fifth of the night in early adulthood to just a few percent by midlife. Across large studies, ageing is linked to less deep sleep, more night-time waking and lighter, more broken sleep overall.
Nitric oxide follows a similar curve. NO availability in the blood vessels declines steadily with age, and by around 40 most adults make roughly half the nitric oxide they did at 20.
The two declines run in parallel, and they share mechanisms:
- Less sleep pressure: the NO–adenosine signal that drives deep sleep may weaken.
- Poorer heat release: stiffer, less responsive blood vessels make it harder to cool down for sleep.
- More inflammation: lower healthy NO and more oxidative stress feed the inflammation–poor sleep cycle.
We can't yet say that falling NO causes poorer sleep with age. But the overlap is striking, and it gives us practical targets.
The metabolic link: blood sugar, nitric oxide and sleep
Metabolic health is where these threads come together.
How metabolic health lowers nitric oxide
Insulin normally does two jobs: it moves glucose into cells, and it switches on NO production in the blood vessels, which increases blood flow to muscles so they can take up that glucose. When cells become less responsive to insulin (insulin resistance), the NO side of that signal is blunted.
Excess abdominal (visceral) fat adds to the problem. It releases inflammatory signals and increases oxidative stress, which breaks down NO faster than the body can make it.
How poor sleep damages metabolic health
Sleep loss works the other way. In a landmark study, healthy young men restricted to four hours' sleep for under a week showed glucose responses typical of much older adults. Short sleep also raises hunger hormones and lowers fullness hormones, which pushes food choices and weight in the wrong direction.
The cycle
Put together, it looks like this:
Poor sleep → reduced insulin sensitivity and more abdominal fat → more inflammation and lower NO → weaker sleep signals and poorer circulation → worse sleep.
Heavy snoring and disrupted breathing at night often sit inside this cycle too, and are associated with lower NO levels. If you or your partner notice them, they're worth raising with your health professional.
Where nitric oxide helps
Supporting healthy NO addresses several links in the cycle at once. Healthy NO signalling supports blood flow to muscle and normal glucose uptake, healthy blood pressure within the normal range, healthy mitochondrial function and balanced inflammation. Better metabolic health supports better sleep, and better sleep supports metabolic health.
How to support nitric oxide for better sleep
- Eat nitrate-rich vegetables daily: beetroot, rocket, spinach, silverbeet, celery and lettuce.
- Look after your mouth bacteria: antiseptic mouthwash can wipe out the bacteria that convert nitrate to NO.
- Breathe through your nose: the nasal sinuses produce NO, and nasal breathing carries it into the lungs.
- Move every day: exercise is one of the strongest natural stimulators of NO production.
- Get morning light and keep regular sleep times: these anchor the body clock that times sleep.
- Keep the evening cool: a cool bedroom and a warm shower before bed help heat release.
- Limit alcohol late in the day: it fragments sleep and disrupts metabolic recovery.
- Test, don't guess: a simple saliva test shows where your NO levels sit and whether changes are working.
For more sleep habits, see 10 ways to optimise sleep.
Ultimate 4: daily support for healthy nitric oxide
Habits come first. But the decline in NO with age is real, and most of us can't eat enough beetroot and rocket to make up the difference. That's why I formulated Ultimate 4 — a daily nitric oxide powder that supports both of the body's NO pathways at once.
- The arginine pathway: 1,620mg of L-citrulline, which the body converts to arginine and then to NO. Citrulline raises arginine levels more reliably than taking arginine itself.
- The nitrate pathway: beetroot and rocket (arugula) extracts provide dietary nitrate, which the body converts to NO. This pathway becomes more important as we age, when the enzyme-driven pathway slows.
- Protection: vitamin C and hibiscus help protect NO from oxidative stress — the same stress that rises with poor metabolic health.
- Supporting nutrients: glycine, taurine and magnesium (as magnesium taurate), which are involved in normal nervous system and muscle function.
It's one scoop a day. Ultimate 4 isn't a sleeping aid — it's designed to support healthy nitric oxide levels, which sit underneath circulation, metabolic health and the brain's own sleep signalling. The best way to use it is to test your NO first, take Ultimate 4 daily, then retest after a few weeks so you can see your levels move.
What the science does and doesn't show yet
The evidence that the body's own NO helps regulate sleep is strong. What we don't yet have is clinical trial evidence that taking an NO-supporting supplement or eating more nitrate directly improves sleep. I'd rather be clear about that. What we do know is that healthy NO supports circulation, metabolic health and inflammatory balance — the foundations restorative sleep is built on.
Frequently asked questions
Does nitric oxide make you sleepy?
Not directly like a sedative. NO is one of the signals that builds sleep pressure during the day and helps the brain move into deep sleep at night.
What supplement supports nitric oxide as we age?
Formulas that combine L-citrulline (the arginine pathway) with dietary nitrate from beetroot or leafy greens (the nitrate pathway) support both of the body's NO pathways. Ultimate 4 combines both, with vitamin C and antioxidants to help protect NO once it's made.
Should I take nitric oxide support at night?
There isn't clinical evidence for a best time of day for sleep. Ultimate 4 is taken as one scoop daily — consistency matters more than timing. Always follow the directions on the label.
Why do I wake up more often as I get older?
Deep sleep naturally declines with age, so sleep becomes lighter and easier to interrupt. Falling NO, changes in metabolic health and inflammation are all thought to contribute.
Is beetroot good for sleep?
Beetroot is one of the richest sources of dietary nitrate, which the body converts to NO. It supports healthy circulation, though there isn't yet direct research showing it improves sleep.
How do I know if my nitric oxide is low?
Saliva test strips give a simple at-home reading in seconds. Learn how to test and optimise your nitric oxide.
Have you noticed your sleep change as your health or metabolism has changed? Join the conversation in our Butterworth Health Optimisation community.
Jeff Butterworth N.D — Specialist Naturopath, 30 years in clinical practice
References
- Gautier-Sauvigné S, et al. Nitric oxide and sleep. Sleep Medicine Reviews. 2005;9(2):101–113.
- Kalinchuk AV, et al. Nitric oxide production in the basal forebrain is required for recovery sleep. Journal of Neurochemistry. 2006;99(2):483–498.
- Kräuchi K, et al. Warm feet promote the rapid onset of sleep. Nature. 1999;401:36–37.
- Van Cauter E, Leproult R, Plat L. Age-related changes in slow wave sleep and REM sleep and relationship with growth hormone and cortisol levels in healthy men. JAMA. 2000;284(7):861–868.
- Ohayon MM, et al. Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals. Sleep. 2004;27(7):1255–1273.
- Taddei S, et al. Age-related reduction of NO availability and oxidative stress in humans. Hypertension. 2001;38(2):274–279.
- Muniyappa R, Sowers JR. Role of insulin resistance in endothelial dysfunction. Reviews in Endocrine and Metabolic Disorders. 2013;14(1):5–12.
- Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. The Lancet. 1999;354(9188):1435–1439.
- Irwin MR, Olmstead R, Carroll JE. Sleep disturbance, sleep duration, and inflammation. Biological Psychiatry. 2016;80(1):40–52.
- Lundberg JO, Weitzberg E, Gladwin MT. The nitrate–nitrite–nitric oxide pathway in physiology and therapeutics. Nature Reviews Drug Discovery. 2008;7(2):156–167.
- Schwedhelm E, et al. Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine. British Journal of Clinical Pharmacology. 2008;65(1):51–59.
This article is for general education and is not a substitute for individual health advice. Always read the label and follow the directions for use. If symptoms persist, talk to your health professional.