Cortisol and Sleep: Does a Stress Hormone Explain Waking at Night?

One sleep supplement’s sales page tells a cortisol story: a stress hormone that spikes at night and wakes you, and an ingredient that brings it down. This guide explains what cortisol is, what research links it to insomnia, and how one product’s cortisol claim holds up against the studies we could find.

It is not medical advice. If sleep trouble is persistent, talk to a healthcare provider.

The Short Answer

Cortisol follows a daily rhythm. A 2025 review says that in healthy people most cortisol secretion occurs within several hours around morning awakening, with a rapid rise in the first 30 to 45 minutes after waking.
People with insomnia have moderately higher cortisol on average. A meta-analysis of 20 case-control studies found a standardized mean difference of 0.50. That is an association. It does not show which way the cause runs.
We found no study showing that a cortisol spike wakes people at 3 a.m. Our PubMed search for cortisol together with waking at 3 a.m. or in the middle of the night returned one paper, from 1987, on mood and cortisol in depression.
We found no controlled trial showing that lemon balm reduces cortisol. Two controlled trials of herbal combinations that included lemon balm found no difference in cortisol. One small analysis reported a decline with a lemon balm product, and its abstract describes no comparison group.
The best-supported help for chronic insomnia is cognitive behavioral therapy for insomnia (CBT-I). See our guide on waking up at night.

What Cortisol Does and When It Rises

Cortisol is a hormone released in a daily pattern. Stalder and colleagues’ 2025 review says that in healthy individuals the majority of cortisol secretion occurs within several hours surrounding morning awakening. The cortisol awakening response is the rapid increase in cortisol across the first 30 to 45 minutes after waking. The authors propose that this burst helps prepare the body for the day ahead (Stalder et al., 2025).

Cortisol is also one of the body-clock markers researchers measure. In the 1999 study that found the human clock runs at about 24.18 hours, the timing of the cortisol rhythm was measured along with melatonin and body temperature (Czeisler et al., 1999). Our guide on the circadian rhythm explains the clock itself.

What Research Links to Insomnia

Dressle and colleagues pooled 20 case-control studies, with 449 people who had insomnia (aged 18 to 70, not taking medications) and 357 good sleepers. People with insomnia had moderately increased cortisol, with a standardized mean difference of 0.50 (95% CI 0.21 to 0.80), and the difference was larger in studies that used blood samples (0.67). The link between how much objective sleep a person lost and the cortisol difference was positive but not significant. The authors declare no conflicts of interest (Dressle et al., 2022).

A 2025 umbrella review of six meta-analyses compared people with insomnia disorder and controls. The largest objective differences were in nonspecific stress markers, cortisol among them, while the differences in subjective sleep were larger and more consistent. The authors read the pattern as supporting a biopsychosocial view of chronic insomnia with a strong psychological component (Hertenstein et al., 2025).

These are comparisons between people with and without insomnia. They do not show whether stress hormones disturb sleep, whether poor sleep raises stress hormones, or whether a third thing drives both. A 2023 review of hyperarousal in insomnia says recent evidence points to a role for neuroendocrine variables and that longitudinal studies are needed (Dressle and Riemann, 2023).

One Product’s Claim

The sales page for Yu Sleep, a liquid supplement, makes a specific claim about cortisol and waking at 3 a.m. We read it on September 19, 2026. About lemon balm extract, it says: “It reduces cortisol - the stress hormone that spikes in the middle of the night when you’re stressed. Thanks to it, you’ll STOP waking up at 3 AM.” It also says: “The 3 AM wake-ups become less frequent, sometimes even stop completely.” Those are the seller’s words, not ours. There are three claims inside them.

“Cortisol spikes in the middle of the night when you’re stressed.” The 2025 review places most cortisol secretion in the hours around morning awakening, and its abstract does not describe a mid-night spike. We searched PubMed titles and abstracts for cortisol together with waking at “3 am”, “3 a.m.” or “middle of the night”. We found one paper, from 1987, on diurnal variation of mood and the cortisol rhythm in depression. That does not prove no such study exists. We did not find a source for the claim as worded.

“Lemon balm reduces cortisol.” We found three studies that measured cortisol with lemon balm:

Mazzola and colleagues, 2026. A secondary analysis of 12 adults with poor sleep quality and emotional distress who took 400 mg a day of a lemon balm extract formulated in phospholipids for 3 weeks. Salivary cortisol fell over the 3 weeks (P < 0.001). The authors call it preliminary evidence of an association. The abstract describes no comparison group. One author is an employee of Indena, which owns the Relissa and Phytosome trademarks named in the paper, and the authors report no specific funding (Mazzola et al., 2026).
Gutiérrez-Romero and colleagues, 2024. A randomized, placebo-controlled trial in adults with impaired sleep of a combination of L-theanine, lemon balm, valerian and saffron for 6 weeks. It did not improve objective or subjective sleep more than placebo, and salivary cortisol stayed unchanged in both groups. It was funded by Team Foods Colombia, and several of the authors work in research and development at that company. The paper says the sponsor was not involved in the study conduct, the analysis or the decision to publish (Gutiérrez-Romero et al., 2024).
Meier and colleagues, 2018. A randomized, placebo-controlled trial of 72 healthy men given a combination of valerian, passion flower, lemon balm and butterbur (Ze 185) before a standardized stress test. The cortisol response did not differ between groups. Self-reported anxiety responses were lower than with placebo. Several authors are at Max Zeller Söhne AG, a Swiss company (Meier et al., 2018).

So the only reported decline came from a 12-person analysis of one formulation with no described comparison group, and the two controlled trials of combinations found no cortisol difference. None of them tested Yu Sleep. Our side-effects guide works out that, if the label lists ingredients by weight, the lemon balm in Yu Sleep can be at most about 159 mg. The real amount could be much lower, and the label does not say.

“Thanks to it, you’ll STOP waking up at 3 AM.” None of the studies above tested waking at 3 a.m. The trial of a combination did measure time awake after falling asleep, and it did not differ significantly between groups (p = 0.33). The sales page’s own list of 20 studies does not help either: our legitimacy guide found that none of the 17 indexed in PubMed mentions cortisol. The claim has no source that we could find.

None of this shows that lemon balm does nothing. A 2025 scoping review of 51 randomized trials of over-the-counter products for insomnia lists “lemon balm and fennel” among the products with promising results compared with prescription medication alone. The authors call the findings for over-the-counter products promising but inconclusive (Salame et al., 2025). That is about sleep, not cortisol.

What Has Evidence for Waking at Night

Our guides on why you keep waking up at night and why you might wake at 3 a.m. go through the causes health agencies list, including stress, worry about sleep, alcohol, caffeine, noise, light, temperature, age and sleep apnea. For chronic insomnia, the American College of Physicians and the American Academy of Sleep Medicine give CBT-I a strong recommendation.

What We Do Not Know

Whether cortisol causes waking in the night. Studies compare groups. We found none that tests it at 3 a.m.
Whether reducing cortisol would improve sleep. The trials above measured cortisol as an outcome. We found none that tested this in people with insomnia.
Whether lemon balm affects cortisol. The results conflict, and the positive one is small and from a maker-linked formulation.
What is in Yu Sleep. The label gives no amount for lemon balm.

Questions

Does cortisol wake you up at 3 a.m.?

We found no study showing it. Cortisol rises around morning awakening in healthy people, and NHLBI’s pages on insomnia do not link waking to a particular hour.

Do people with insomnia have high cortisol?

On average, moderately higher, in a meta-analysis of 20 case-control studies. It is an association, and it does not show cause.

Does lemon balm reduce cortisol?

The evidence conflicts. Two controlled trials of combinations that included lemon balm found no cortisol difference, and one small analysis of a single formulation reported a decline.

Can a supplement fix a cortisol spike?

We found no evidence that a cortisol spike is why people wake at night, so we cannot say a supplement fixes one. If stress or worry keeps you awake, talk to a healthcare provider about the approaches with evidence.

Sources Cited in This Guide

Stalder T, Oster H, Abelson JL, et al. “The Cortisol Awakening Response: Regulation and Functional Significance.” Endocr Rev. 2025. Read September 19, 2026 (abstract). PMID 39177247
Czeisler CA, et al. “Stability, precision, and near-24-hour period of the human circadian pacemaker.” Science. 1999. Read September 19, 2026 (abstract). PMID 10381883
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. Read September 19, 2026 (abstract). PMID 35091194
Hertenstein E, Angelillo M, Henckaerts P, et al. “Comparing subjective and objective nighttime- and daytime variables between patients with insomnia disorder and controls - a systematic umbrella review of meta-analyses.” Sleep Med Rev. 2025. Read September 19, 2026 (abstract). PMID 40850055
Dressle RJ, Riemann D. “Hyperarousal in insomnia disorder: Current evidence and potential mechanisms.” J Sleep Res. 2023. Read September 19, 2026 (abstract). PMID 37183177
Mazzola G, Rondanelli M, Lazzarotti A, et al. “Salivary cortisol dynamics and their relationship with sleep and mental well-being in adults receiving a phospholipid-based Melissa officinalis supplement: a secondary analysis in a subpopulation.” Food Nutr Res. 2026. Read September 19, 2026 (abstract and conflict statement). PMID 42232738
Gutiérrez-Romero SA, Torres-Narváez ES, Zamora-Gómez AC, et al. “Effect of a nutraceutical combination on sleep quality among people with impaired sleep: a randomised, placebo-controlled trial.” Sci Rep. 2024. Read September 19, 2026 (abstract and conflict statement). PMID 38580720
Meier S, Haschke M, Zahner C, et al. “Effects of a fixed herbal drug combination (Ze 185) to an experimental acute stress setting in healthy men - An explorative randomized placebo-controlled double-blind study.” Phytomedicine. 2018. Read September 19, 2026 (abstract and affiliations). PMID 29433687
Salame A, Mathew S, Bhanu C, et al. “Over-the-counter products for insomnia in adults: A scoping review of randomised controlled trials.” Sleep Med. 2025. Read September 19, 2026 (abstract). PMID 40054227
Yu Sleep sales page, getyusleep.com. Read September 19, 2026. Cited only for the seller’s own wording; not used as a source for any claim.

This guide is for information and is not medical advice. Talk to a healthcare provider about medication, pregnancy, medical conditions and persistent sleep problems.