Tired But Can’T Sleep — The Supplement Approach

Tired But Can’t Sleep? Here’s What the Research Actually Says About Supplements

There’s a particular kind of exhaustion that feels almost cruel. You’re bone-tired. Your eyes are heavy. You’ve done everything right, you’ve put the phone down, the room is dark, the temperature is cool. And then you lie there, wide awake, your brain humming quietly to itself like a refrigerator that nobody can switch off. Sound familiar?

If it does, you’re in very good company. Poor sleep quality affects tens of millions of adults, and nearly one in five regularly reach for some kind of sleep aid, prescription or over-the-counter, just to get through the night [7]. But here’s the question most people don’t ask: what if the gap between being tired and actually sleeping isn’t just about stress or bad habits, but about specific nutrients your body needs to make the chemical handover from wakefulness to sleep? What if the problem isn’t willpower, it’s biochemistry?

Vitacuity analysed over 1.77 million research papers and selected the most relevant studies on this exact question. What follows is an honest, clear-eyed look at what supplements the research actually supports for sleep, and where the evidence still has gaps.

The Science Behind the Tired-But-Wired Problem

To understand why supplements might help, it helps to understand what sleep actually requires from your body.

Sleep isn’t simply the absence of wakefulness. It’s an active, carefully orchestrated biological process, one that depends on a cascade of neurotransmitters, hormones and cellular signals firing in exactly the right sequence [1]. Memory consolidation, immune regulation, physical recovery and emotional processing all happen while you sleep. Miss out on 7–9 hours of quality rest consistently, and the risks to cardiovascular, metabolic and cognitive health are well established [4].

The transition from wakefulness to sleep involves several key players. Melatonin, produced by the pineal gland in response to darkness, signals to the body that night has arrived. Serotonin is a precursor to melatonin, and is itself made from the amino acid tryptophan, which your body cannot produce on its own and must get from food. GABA (gamma-aminobutyric acid), the brain’s main calming neurotransmitter, quiets neural activity. Magnesium supports GABA receptor function. Cortisol, the stress hormone, needs to drop as evening approaches, and when it doesn’t (hello, modern life), it actively interferes with melatonin production.

So the “tired but can’t sleep” experience often reflects a breakdown somewhere in this chain. The nervous system is stuck in a low-level alert state, and the chemical signals needed to override it are either insufficient or poorly timed. This is where nutrition and targeted supplementation can, in certain cases, genuinely help.

Magnesium: The Mineral That Tells Your Nervous System to Stand Down

Evidence grade: Promising, some human trial data, but results are mixed and sample sizes vary

Magnesium might be the most underappreciated sleep nutrient in most people’s diets. It plays a direct role in activating GABA receptors, the same receptors that many prescription sleep medications target, and helps regulate the nervous system’s transition from a high-alert state to a calm, sleep-ready one [1, 7].

A randomised, double-blind, placebo-controlled trial published in *Open Access Macedonian Journal of Medical Sciences* (2019) gave 30 patients a combined supplement containing 175mg of liposomal magnesium oxide, melatonin (1mg), vitamin B6 (10mg), vitamin B12 (16μg) and folate (600μg) once daily for three months [10]. The results were notable: average insomnia scores (measured on the Athens Insomnia Scale) dropped from 14.93 to 10.50 in the treatment group, a meaningful improvement, while the placebo group’s scores actually worsened slightly, moving from 14.37 to 15.13. The difference between groups was statistically significant (p = 0.000).

The honest caveat: this was a combination supplement, so it’s impossible to isolate how much of the benefit came from magnesium specifically versus the other ingredients. That said, several reviews confirm that adequate magnesium status is consistently associated with better sleep, while deficiency is linked to sleep disturbance [2, 8]. Given how common magnesium insufficiency is in adults eating a modern diet, the risk-benefit calculation here is straightforward.

Melatonin: The Most Studied Sleep Supplement, and the Most Misunderstood

Evidence grade: Conflicted, well-researched, but results vary significantly depending on dose, timing, and the type of sleep problem

Melatonin is the body’s darkness signal. When the sun sets, your pineal gland begins releasing it, quietly telling every cell in your body that night is coming and it’s time to wind down [4]. Supplemental melatonin, in theory, reinforces this signal, particularly useful if you’re struggling with circadian rhythm disruption (shift work, jet lag, late-night screen exposure) rather than straightforward insomnia.

The research is extensive but genuinely conflicted, and it’s worth understanding *why*. Studies use wildly different doses (anywhere from 0.5mg to 10mg), different populations (shift workers vs. older adults vs. otherwise healthy sleepers), and measure different outcomes (sleep onset vs. total sleep time vs. sleep quality) [7, 9]. This makes direct comparison difficult.

What does seem clear from the weight of evidence is that melatonin is most effective for circadian-related sleep issues rather than pure insomnia driven by anxiety or hyperarousal [3, 9]. It also appears to work better at lower physiological doses (0.5–2mg) taken at the right time, typically 30–60 minutes before bed, rather than the very high doses often found in US supplements [1].

For the “tired but wired” person whose sleep problems relate to irregular schedules, late light exposure, or a shifted body clock, melatonin has genuine evidence behind it. For chronic, anxiety-driven insomnia, the picture is less clear.

L-Theanine: Calm Without Sedation

Evidence grade: Promising, human data exists, though most trials are small

L-theanine is an amino acid found naturally in green tea. It doesn’t sedate you, it relaxes you, which is a meaningful distinction. It promotes alpha brain wave activity, the kind associated with calm alertness, and appears to support GABA pathways without causing drowsiness during the day [1, 7].

A crossover study published in *Nutrients* (2023) examined four supplements, L-theanine (200mg/day), GABA (111.1mg/day), and two other formulas, in 160 participants over repeated intervention periods [12]. The researchers found that individual responses varied considerably based on pre-existing lifestyle habits and sleep conditions, a finding that’s actually quite useful. It suggests that L-theanine may work particularly well for people whose sleep problems are rooted in an overactive, anxious mind rather than a disrupted body clock.

A separate randomised, double-blind crossover study published in *Medicine & Science in Sports & Exercise* (2023) used a multi-ingredient blend containing L-theanine alongside tryptophan, glycine, magnesium and tart cherry powder in 16 participants aged around 24 [11]. The results were impressive: sleep onset latency was reduced by an average of 24 minutes (p = 0.002), total sleep time increased by 22 minutes (p = 0.01), and sleep efficiency improved by 2.4% (p = 0.03). Morning sleepiness also dropped significantly. The sample was young and small, so we shouldn’t overinterpret, but the direction of effect is consistent with the broader literature.

The Tryptophan-Serotonin-Melatonin Pipeline: Why What You Eat Matters

Evidence grade: Promising, strong mechanistic rationale, some human trial support

Here’s something that doesn’t get nearly enough attention: your body makes melatonin from serotonin, and serotonin from tryptophan. That means if you’re not getting enough tryptophan, an essential amino acid found in foods like turkey, eggs, milk and oily fish, your body may simply not have the raw materials to produce adequate melatonin, regardless of how dark your bedroom is [2].

But tryptophan has a frustrating commute problem. To get into the brain, it has to cross the blood-brain barrier, and it’s competing for transport against other larger amino acids (called long-chain neutral amino acids, or LCNAAs). The ratio of tryptophan to LCNAAs in a given food actually matters more than the absolute tryptophan content. This is why milk and eggs, despite not being the highest sources of tryptophan in absolute terms, are particularly associated with sleep benefits: their tryptophan-to-LCNAA ratio is favourable [2, 8].

B vitamins play a supporting role here too. Pyridoxine (B6), B12, folate and niacin all appear to support the enzymatic steps in the tryptophan-to-serotonin-to-melatonin conversion pathway [2, 8]. The 2019 RCT discussed above included B6 and B12 alongside melatonin and magnesium, and saw significant sleep improvements over three months, though again, the combination makes isolating individual contributions difficult [10].

Ashwagandha and Adaptogens: Targeting the Stress Root Cause

Evidence grade: Promising, growing human trial data, particularly for stress-related sleep disruption

For many people in the 40–65 age bracket, the “tired but wired” pattern has a very clear driver: sustained, low-grade stress that keeps cortisol elevated into the evening hours. This is where adaptogenic herbs, particularly ashwagandha, enter the picture.

Ashwagandha (*Withania somnifera*) appears to work by modulating the hypothalamic-pituitary-adrenal (HPA) axis, essentially, the body’s stress response system. By blunting excessive cortisol output, it may help the nervous system make the transition to sleep that cortisol was blocking [1, 3]. Multiple reviews now include ashwagandha among the nutraceuticals with meaningful evidence for sleep quality improvement, particularly in people whose insomnia has a stress or anxiety component [1, 3, 9].

Valerian root is another herbal option with a longer research history. It appears to act on GABA and serotonin receptors, and several reviews find it may reduce the time it takes to fall asleep and improve subjective sleep quality, though the evidence base is inconsistent and optimal doses remain unclear [3, 9]. Lemon balm, passionflower, and chamomile are also mentioned in the literature as having GABA-modulating properties, though most of the clinical evidence is smaller in scale [3, 15].

Glycine: The Quiet Achiever

Evidence grade: Promising, limited but interesting human data

Glycine is a non-essential amino acid, your body can make it, but not necessarily in the quantities needed for optimal sleep. It appears to lower core body temperature slightly (an important signal for sleep onset) and to interact with NMDA receptors in ways that promote deeper, more restorative sleep stages [1].

The multi-ingredient study from *Medicine & Science in Sports & Exercise* (2023) included glycine in its blend and observed improvements in sleep onset, duration and efficiency, though as noted, individual ingredients can’t be cleanly separated [11]. Glycine is inexpensive, widely available, generally very well tolerated, and has a plausible mechanistic rationale. It’s the kind of supplement that a sensible person would think: low risk, potentially real benefit, worth a try.

Vitamin D: Not Just a Bone Vitamin

Evidence grade: Promising, observational data is consistent; fewer high-quality intervention trials

Vitamin D deficiency is astonishingly common in the UK, particularly in the winter months, and emerging evidence links it to sleep disturbance [2, 7, 8]. Vitamin D receptors are found in brain regions involved in sleep regulation, and low levels appear to be associated with shorter sleep duration and poorer sleep quality.

The intervention trial evidence is thinner than the observational data, and more research is needed [7]. But given how widespread deficiency is in the UK population, and given that vitamin D at standard doses (1,000–4,000 IU) has an excellent safety profile, this is a supplement that makes sense to take regardless, particularly through autumn and winter.

What We Don’t Know Yet

Let’s be honest about the limits of what the research can tell us.

Most studies are short. Many trials run for just a few days to a few weeks. Sleep patterns can shift with seasons, life circumstances and age, and what works for three days in a lab might behave differently over six months of real life [7, 9].

Most samples are small. The impressive multi-ingredient study cited above had just 16 participants [11]. The RCT showing magnesium/melatonin/B vitamin benefits had 60 participants [10]. These are genuinely promising signals, but we need larger, independent replications before we can be fully confident.

Combination supplements dominate the research. Several of the more compelling studies used blends rather than single ingredients, which makes it very difficult to know which compound is doing the heavy lifting, or whether it’s the synergy between them that matters [10, 11].

Individual variation is real and significant. The 2023 crossover trial in *Nutrients* found that the same supplement had quite different effects depending on each person’s pre-existing habits and sleep profile [12]. This matters practically: what works brilliantly for one person may do very little for another. Sleep problems are not one-size-fits-all.

Optimal doses are largely unestablished. For melatonin in particular, the range studied runs from 0.5mg to 10mg, a twentyfold difference, and the literature is inconsistent across this range [7, 9]. For most herbal supplements, standardisation of extracts is also a real problem, meaning one brand’s “valerian” might be very different biochemically from another’s.

The herbal evidence base needs strengthening. Many of the herbs reviewed, chamomile, lemon balm, passionflower, have compelling traditional use and plausible mechanisms, but still lack large, well-designed RCTs to confirm their efficacy convincingly [3, 9, 15].

The Final Takeaway

So what would a sensible, well-informed person actually do with all of this?

First, recognise that the “tired but can’t sleep” pattern is almost always multi-factorial. It’s rarely about one missing nutrient. More often it’s a combination of a depleted biochemical system, low-grade chronic stress, disrupted circadian signals (too much light at night, not enough in the morning), and nutritional gaps that accumulate over years. Supplements work best as part of a broader approach, not instead of sleep hygiene, but alongside it.

That said, here’s what the research genuinely supports:

Magnesium (200–400mg, taken in the evening) is probably the single highest-value supplement for sleep in this age group. Deficiency is common, it’s inexpensive, it’s well-tolerated, and the mechanistic rationale is solid. Take it daily, there’s minimal downside.

L-theanine (200mg, 30–60 minutes before bed) is a low-risk, reasonable option if your sleep problem involves an overactive, anxious mind. It won’t knock you out, but it may take the edge off the mental noise that keeps you staring at the ceiling.

Melatonin (0.5–2mg, 30–60 minutes before bed) makes most sense if your sleep problem is circadian in nature, you’re a night owl who needs to sleep earlier, you’re doing shift work, or you’ve been hit by jet lag. Start low. There is no strong evidence that higher doses work better for most people, and some evidence that lower doses are more physiologically appropriate.

B vitamins (B6, B12, folate) support the tryptophan-to-melatonin pathway. These are water-soluble, excess is excreted, so daily supplementation is safe, practical and needs no testing. If you’re not taking a B complex already, there’s a reasonable case to start.

Vitamin D (1,000–2,000 IU daily through winter months) is worth taking regardless of sleep, but the emerging sleep data adds another reason. At these doses, it’s very safe. In the UK, the risk of deficiency is far more real than the risk of excess.

Ashwagandha is worth considering if chronic stress is clearly part of your picture, the kind of background hum of pressure that keeps you alert when you’d rather be asleep. The evidence for stress reduction is stronger than for sleep specifically, but the two are clearly linked.

Glycine is low risk, inexpensive, and has an interesting emerging rationale. A small dose (2–3g before bed) is a reasonable experiment, particularly if the other fundamentals are already in place.

Finally: pay attention to what you eat in the evenings. Oily fish, milk, eggs, kiwi fruit and tart cherries all appear in the literature as having sleep-supportive properties [1, 2]. Alcohol feels like a sleep aid, it’s not. It fragments sleep architecture and suppresses the deep, restorative stages your brain genuinely needs [2, 3].

Sleep isn’t a luxury. It’s the maintenance window for everything else you care about, your memory, your mood, your immune system, your heart. The research says there are real, safe, evidence-based ways to support it. A sensible stack, magnesium, L-theanine, perhaps low-dose melatonin and B vitamins, is a reasonable starting point for most people.

Try it for four weeks. Notice what changes. Adjust from there.

References

[1] Dietary Protocols to Promote and Improve Restful Sleep: A Narrative Review. (2025). *Nutrition Reviews*. DOI: 10.1093/nutrit/nuaf062 | https://pubmed.ncbi.nlm.nih.gov/40418260/

[2] Nutrition in improving sleep quality and fighting insomnia. (2025). *Nutrición Hospitalaria*. DOI: 10.20960/nh.06090 | https://pubmed.ncbi.nlm.nih.gov/40728459/

[3] Integrative sleep management: from molecular pathways to conventional and herbal treatments. (2025). *Naunyn-Schmiedeberg’s Archives of Pharmacology*. DOI: 10.1007/s00210-025-04183-y | https://pubmed.ncbi.nlm.nih.gov/40338321/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12511158/

[4] Improving Sleep Quality to Enhance Athletic Activity, The Role of Nutrition and Supplementation: A Mini-Short Review. (2025). *Nutrients*. DOI: 10.3390/nu17111779 | https://pubmed.ncbi.nlm.nih.gov/40507048/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12157846/

[5] Effect of diamine oxidase (DAO) enzyme dietary supplementation in subjects with insomnia symptoms and single nucleotide polymorphisms. (2026). *Sleep Medicine: X*. DOI: 10.1016/j.sleepx.2025.100167 | https://pubmed.ncbi.nlm.nih.gov/41437955/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12721298/

[7] Current Evidence on Common Dietary Supplements for Sleep Quality. (2024). *American Journal of Lifestyle Medicine*. DOI: 10.1177/15598276241227915 | https://pubmed.ncbi.nlm.nih.gov/38737872/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11082867/

[8] Nutrition in improving sleep quality and fighting insomnia. (2025). *Nutrición Hospitalaria*. DOI: 10.20960/nh.06090 | https://pubmed.ncbi.nlm.nih.gov/40728459/

[9] Herbal and Natural Supplements for Improving Sleep: A Literature Review. (2024). *Psychiatry Investigation*. DOI: 10.30773/pi.2024.0121 | https://pubmed.ncbi.nlm.nih.gov/39086164/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11321869/

[10] The Effects of Magnesium–Melatonin–Vit B Complex Supplementation in Treatment of Insomnia. (2019). *Open Access Macedonian Journal of Medical Sciences*. DOI: 10.3889/oamjms.2019.771 | https://pubmed.ncbi.nlm.nih.gov/31850132/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6910806/

[11] Nutritional Modulation of Sleep Latency, Duration, and Efficiency: A Randomized, Repeated-Measures, Double-Blind Deception Study. (2023). *Medicine & Science in Sports & Exercise*. DOI: 10.1249/MSS.0000000000003040 | https://pubmed.ncbi.nlm.nih.gov/36094342/

[12] Analysis of the Effects of Known Sleep-Support Supplements in Relation to Life Habits, Sleep Conditions, and Sleep Problems. (2023). *Nutrients*. DOI: 10.3390/nu15102377 | https://pubmed.ncbi.nlm.nih.gov/37242260/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10220724/

[15] Nutraceuticals for Sleep Disorders. (2021). *Current Molecular Pharmacology*. DOI: 10.2174/1386207324666210121111446 | https://pubmed.ncbi.nlm.nih.gov/33475068/

This article is for informational purposes only and does not constitute medical advice. Food supplements should not be used as a substitute for a varied and balanced diet and healthy lifestyle. If you are pregnant, breastfeeding, taking medication or have a medical condition, consult your doctor before taking any supplement. These statements have not been evaluated by the Food and Drug Administration (FDA) or the Medicines and Healthcare products Regulatory Agency (MHRA). This product is not intended to diagnose, treat, cure, or prevent any disease.