Why melatonin doesn't work for stress-related sleep problems

Why melatonin doesn't work for stress-related sleep problems

Melatonin is a circadian hormone, not a sedative. It tells your brain that night has arrived — it does not switch off the arousal systems that stress keeps active. When the core problem is elevated cortisol rather than a disrupted body clock, melatonin addresses the wrong mechanism entirely. Research consistently shows that chronic insomnia driven by stress is characterised by elevated HPA axis activity across the 24-hour cycle, a pattern that melatonin supplementation does not reliably correct. For stress-driven sleep disruption, the evidence points toward approaches that directly target the hypothalamic-pituitary-adrenal (HPA) axis — the stress response system that keeps the brain alert long after the working day ends. Melatonin remains a well-supported tool for circadian rhythm disorders, but the "wired but tired" experience that many people describe is a different physiological problem, and it calls for a different approach.

What does melatonin actually do in the body?

Melatonin is a hormone produced by the pineal gland, a small structure deep in the brain. Its release is triggered by darkness and suppressed by light, and its primary biological function is to transmit a nighttime signal to the suprachiasmatic nucleus — the master circadian clock — and to peripheral tissues throughout the body. In pharmacological terms, melatonin is a zeitgeber: a time-giver that synchronises the body's internal clock to the external environment.

It does not cause sleep directly. It does not suppress the sympathetic nervous system, reduce cortisol, or turn down the activity of the brain's arousal circuits. This is not a limitation unique to exogenous melatonin supplements — it is a description of what the hormone is and does. A useful analogy is a train schedule: melatonin announces that the sleep train is due. If the tracks are clear, the train arrives. If the tracks are blocked by an active stress response, the announcement changes nothing.

The evidence reflects this. Meta-analyses of melatonin in primary chronic insomnia have consistently found modest effects on sleep onset time — typically a reduction of around seven to twelve minutes — with no clinically significant improvement in sleep efficiency or total sleep time. For jet lag and circadian rhythm disorders such as delayed sleep-wake phase disorder, the evidence is considerably stronger, because in those conditions the fundamental problem *is* a timing mismatch, and melatonin is precisely the right signal to correct it.

Why do so many people with stress-driven insomnia still feel wired at night?

Not all insomnia is the same condition wearing the same face. Clinical sleep medicine distinguishes between insomnia rooted in circadian misalignment — the body clock has drifted out of phase with the environment — and insomnia rooted in hyperarousal, where the nervous system remains in a state of elevated activation even when the body is physically exhausted.

The hyperarousal form is what most people are describing when they say they cannot sleep even though they are exhausted. The brain is running at a register too high to allow sleep onset or maintenance, and the physiological signature of this state is elevated activity of the HPA axis. A 2022 systematic review and meta-analysis from the University of Freiburg, led by Raphael Dressle and published in *Sleep Medicine Reviews*, pooled data from 20 case-control studies involving 449 patients with insomnia and 357 healthy sleeper controls, and found consistent evidence of a measurable elevation in cortisol across the 24-hour cycle in the insomnia group — a pattern consistent with persistent HPA axis hyperactivation rather than a simple sleep initiation problem.[1]

This is a meaningful distinction. Cortisol promotes alertness. Its normal evening trajectory — falling through the late afternoon and reaching a nadir around 2 to 3am — is a physiological prerequisite for sleep onset and for the progression into slow-wave sleep. When that decline is blunted by chronic stress or HPA axis dysregulation, the brain receives a sustained arousal signal at precisely the time it needs to wind down. The result is the familiar experience: lie down, body exhausted, mind racing, sleep elusive.

Why doesn't melatonin fix this?

Melatonin can tell the brain that it is night-time. It cannot tell the HPA axis to stand down. The two systems interact — cortisol actively suppresses melatonin secretion, which means that in a state of HPA axis hyperactivation, even endogenous melatonin production is reduced — but the relationship does not run in both directions cleanly. Adding exogenous melatonin on top of elevated cortisol does not reverse the stress response.

A 2024 randomised controlled trial examined exogenous melatonin's effect on salivary cortisol and autonomic stress markers in healthy adults.[2] The authors found that melatonin supplementation did not produce consistent, reliable reductions in cortisol, with results across participants varying considerably. The investigators noted that the relationship between melatonin and HPA axis output remains heterogeneous and inconclusive across the clinical trial literature. For someone whose sleep is disrupted primarily because their stress response has not quietened by 11pm, this matters practically: reaching for melatonin is not reaching for the lever that controls the problem.

This is not a criticism of melatonin as a molecule. It is a description of mechanistic mismatch — the most common reason supplements underperform is that they are reasonable tools applied to the wrong target.

What does the evidence support for stress-driven insomnia?

The adaptogenic approach targets the HPA axis directly. Adaptogens are botanical compounds characterised by their ability to modulate the stress response — not through sedation, but through upstream regulation of the signalling cascade that drives cortisol production.

Ashwagandha (Withania somnifera), specifically standardised root extract, is the most clinically validated adaptogen for this mechanism. Its bioactive withanolide compounds appear to modulate corticotropin-releasing hormone (CRH) signalling at the hypothalamic level, reducing the cascade that leads to elevated evening cortisol. A randomised, double-blind, placebo-controlled trial led by Adrian Lopresti at Murdoch University, Australia, involving 60 adults with moderate-to-high perceived stress, found that 300 mg of standardised ashwagandha extract taken twice daily produced a 23% reduction in serum cortisol at 60 days compared to placebo.[3] A 2021 systematic review and meta-analysis in *PLOS ONE*, pooling five randomised controlled trials with 400 participants, found a statistically significant improvement in overall sleep quality (standardised mean difference -0.59, 95% CI -0.75 to -0.42), with effects most pronounced in adults with insomnia, at doses of 600 mg or more per day, and treatment durations of at least eight weeks.[4] This is a cumulative, gradual mechanism, not a single-night sedative effect, but a recalibration of the stress axis over weeks.

Magnesium bisglycinate supports a different but complementary pathway: parasympathetic nervous system activation. The parasympathetic nervous system — the "rest and digest" counterpart to the stress-driven sympathetic state — needs adequate magnesium as a cofactor for the calcium channel activity that regulates neuronal excitability. Chronic stress depletes magnesium stores, creating a reinforcing cycle in which stress increases demand for magnesium while simultaneously reducing it.

L-theanine, an amino acid found in green tea, increases alpha-wave activity in the brain — the neural signature of calm, unfocused alertness — without causing sedation. In the context of hyperarousal insomnia, it addresses the cognitive dimension: the racing thoughts and inability to disengage mentally that many people experience while physically tired.

Apigenin, a flavonoid derived from citrus peel, acts on GABA-A receptors — the inhibitory neurotransmitter receptors that reduce neuronal firing rate and are central to the natural transition into sleep. Its mechanism overlaps partially with the same pathway used by benzodiazepines and some prescription hypnotics, but without the heavy sedation or dependency risk associated with those classes of drug.

What this means practically

If your sleep problem primarily involves difficulty falling asleep at a consistent time, waking too early relative to your schedule, or disrupted sleep during travel or shift work, melatonin is a well-supported and mechanistically appropriate tool. If your sleep problem is characterised by racing thoughts, difficulty "switching off" despite physical fatigue, waking in the early hours with a sense of alertness or anxiety, or a persistent pattern of feeling exhausted by evening but unable to sleep — the problem is almost certainly HPA axis hyperactivation, and melatonin will not reach it.

ARC's formulation is built around the three-pillar architecture of sleep, stress, and recovery — and it contains no melatonin. Not because melatonin is without value, but because the sleep problem ARC is designed to address requires a different set of levers: the stress response system, the parasympathetic pathway, and the neurochemical conditions for deep, restorative sleep. Understanding the mechanism behind your own sleep difficulty is the first step to choosing an approach that is likely to help.

FAQ

Why does melatonin seem to work for some people with insomnia?

For people whose primary issue is circadian misalignment — a shifted sleep phase, irregular sleep-wake timing, or jet lag — melatonin is a well-supported tool. Even in people with stress-driven insomnia, a modest reduction in sleep onset time (around 7–12 minutes on average) is documented in trials, so some people do perceive a benefit. The question is whether that modest effect is addressing the root mechanism or simply adding a nighttime signal on top of an unresolved stress response. For many people, it is the latter, which explains why melatonin feels only partially helpful or stops working over time.

Can you have elevated cortisol at night and not feel stressed?

Yes. HPA axis dysregulation and subjective stress are not perfectly correlated. Chronic low-grade stress — work pressure, poor recovery, insufficient sleep over weeks or months — can shift the baseline cortisol curve without the person identifying themselves as acutely stressed. The physiological pattern of elevated nocturnal cortisol can persist even when subjective stress scores normalise, which is why addressing the stress axis mechanistically rather than relying on self-reported stress levels is important.

Is it safe to combine melatonin with adaptogens like ashwagandha?

There is no established safety concern with taking both. Melatonin and ashwagandha operate through different mechanisms, and the clinical trials on ashwagandha do not report interactions with melatonin specifically. That said, if stress-driven hyperarousal is the primary problem, combining both is unlikely to be more effective than addressing the HPA axis directly — and it adds complexity without clear benefit. If you are uncertain about which type of insomnia applies to you, speaking to a pharmacist or GP is the most efficient starting point.

*This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before making changes to your supplement routine.*

Written by Cameron Webb, MPharm, PhD: Pharmacist and Founder of NutraWebb

References

1. Dressle RJ, Feige B, Spiegelhalder K, et al. HPA axis activity in patients with chronic insomnia: A systematic review and meta-analysis of case-control studies. *Sleep Med Rev.* 2022;62:101588. doi:10.1016/j.smrv.2022.101588. PMID: 35091194. https://pubmed.ncbi.nlm.nih.gov/35091194/

2. Pachimsawat P, Wanasuntronwong A, Srikam S, et al. Exogenous melatonin's effect on salivary cortisol and amylase: A randomized controlled trial. *Pharmacol Res Perspect.* 2024;12(3):e1205. doi:10.1002/prp2.1205. PMC11103136. https://pmc.ncbi.nlm.nih.gov/articles/PMC11103136/

3. Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (*Withania somnifera*) extract: A randomized, double-blind, placebo-controlled study. *Medicine (Baltimore).* 2019;98(37):e17186. doi:10.1097/MD.0000000000017186

4. Cheah KL, Norhayati MN, Husniati Yaacob L, Abdul Rahman R. Effect of Ashwagandha (*Withania somnifera*) extract on sleep: A systematic review and meta-analysis. *PLOS ONE.* 2021;16(9):e0257843. doi:10.1371/journal.pone.0257843. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8462692/