How to Lower Cortisol: What the Evidence Shows and What It Means for Athletes
Table of Contents
Key Takeaways: How to Lower Cortisol
- Exercise programmes lowered cortisol compared with controls (SMD −0.37) in a meta-analysis of randomised trials, most of which included solely breast cancer patients [1].
- Two nights of 4 hours in bed raised evening total cortisol by 30% and dampened the daily cortisol decline by 21% [2].
- Meditation had a medium-sized effect on blood cortisol, but only in at-risk samples [3].
- Ashwagandha lowered cortisol by 1.16 µg/dL without a significant change in perceived stress [4].
- Cortisol rose by 83.1% in 12 moderately trained men after 30 minutes at 80% of VO₂max [5], in studies using at least 30 g of carbohydrate per hour, carbohydrate attenuated cortisol rises in most cases [6], and 14 days of low energy availability raised cortisol by 22% [7].
- Resting hormone levels, including cortisol, are not good predictors of overtraining syndrome [8].
- In my clinical experience, prolonged stress is most often driven by work or personal circumstances, and it tends to ease when the underlying problem is actually resolved.
- In my view, an isolated cortisol value rarely helps in practice: testing is mainly for ruling out disease such as Cushing’s syndrome, in athletes and sedentary people alike.
Introduction: How to Lower Cortisol Without Fighting Your Own Physiology
Cortisol has become one of the most talked-about hormones online. Search for how to lower cortisol and you will find long lists of supplements, morning routines and warnings that hard training is ruining your hormones.
The controlled research tells a more modest and more useful story. A 2022 systematic review and meta-analysis of randomised trials found that physical activity programmes lowered cortisol compared with controls, with a pooled standardised mean difference (SMD) of −0.37 (95% CI −0.52 to −0.21) [1]. The authors rated this as moderate-certainty evidence that exercise probably lowers cortisol slightly compared with active controls or usual care [1].
The effects discussed here vary in size and certainty, and a measurable change in cortisol does not by itself establish a clinical benefit. Cortisol is also not a hormone you want to switch off. It follows a daily rhythm [1], and it rises during demanding exercise [5].
The question of how to reduce stress comes up in my clinic very often, sometimes several times in a single day. Many of my patients are dealing with the effects of prolonged stress, and in occupational health, where I work, the cause is frequently work-related.
As a physician and former competitive athlete, I want to separate what lowers cortisol in trials from what only sounds plausible. This article covers what cortisol does, what pushes it up, which strategies have trial evidence, what a cortisol test can and cannot tell you, and what it all means for athletes who train hard.
What Cortisol Does, and Why the Daily Pattern Matters More Than One Number
Cortisol is an adrenal hormone released in response to stress, and it follows a strong daily rhythm: levels are high in the morning and fall steadily towards the evening [1]. Shortly after waking there is a brief peak, the cortisol awakening response (CAR), which occurs within the first 30–45 minutes; cortisol then declines through the day to a low point around midnight [1].
The shape of that curve appears to matter. A 2017 systematic review and meta-analysis examined diurnal cortisol slopes, meaning the change in cortisol from morning to evening [9]. Across all included studies, flatter slopes were significantly associated with poorer health (average effect size r = 0.147), and flatter slopes were linked to poorer health in 10 of the 12 subtypes of emotional and physical health outcomes examined [9]. Flatter slopes have been proposed as one pathway between chronic psychosocial stress and poor mental and physical health [9].
These are associations, so they do not prove that a flat cortisol curve causes disease. They may explain why “lower cortisol” is a slightly misleading target. For most healthy people, a well-regulated daily rhythm may be a more realistic goal than the lowest possible number at a single time point.
Persistent, disease-level cortisol excess is a separate medical problem. It is covered in the testing section below.
What Raises Cortisol: Short Sleep, Chronic Stress and Hard Exercise
Before asking how to lower cortisol, it helps to know what pushes it up in the first place. Chronic psychosocial stress is one proposed driver of the flatter daily cortisol slopes described above [9]. Sleep and exercise intensity have been tested more directly.
Prolonged stress in daily life
In occupational health, I see two work situations that patients find especially heavy. In the first, the atmosphere at work is poor and the person has to stay on guard all the time. In the second, the person is under constant observation, which for reasons that are not always clear is very stressful for them. In general terms, stress tends to build when the demands of a situation exceed a person’s capacity to deal with them, and a workload that cannot be managed, combined with too little time to recover, can over time lead to exhaustion. Conflicts at work can also keep stress elevated for a long time, and outside work I see patients living under chronic stress because of difficult relationships, illness, accidents or other traumatic events.
Short sleep shifts the timing of cortisol
In a randomised crossover study, 13 participants completed two nights with 4 hours in bed and two nights with 10 hours in bed [2]. After sleep restriction, evening total cortisol was 30% higher and evening free (salivary) cortisol was 200% higher, and the normal daytime decline in cortisol was dampened by 21% [2]. Morning ACTH, the pituitary hormone that stimulates the adrenal glands, was higher after sleep restriction, but morning cortisol was not [2]. The 21% rise in overall daytime total cortisol did not reach statistical significance (P = .10) [2]. The authors concluded that the effect of sleep loss on the HPA (hypothalamic–pituitary–adrenal) axis depends on time of day [2].
A 2024 meta-analysis of 24 studies adds an important nuance. Overall, acute sleep deprivation did not significantly change cortisol in 21 crossover studies (SMD 0.18; 95% CI −0.11 to 0.45) or 3 randomised trials (SMD 0.26; 95% CI −0.22 to 0.73) [10]. However, the pooled effect was significant in studies that measured serum cortisol (SMD 0.46) and in studies with multiple measurements (SMD 0.28), but not in studies that relied on a single cortisol measurement [10].
One reading of that single experiment is that poor sleep may disturb the rhythm and the evening values more than a single morning number.
Exercise raises cortisol above an intensity threshold
In a classic study, 12 active, moderately trained men performed 30 minutes of exercise at 40%, 60% and 80% of VO₂max, plus a 30-minute resting control session [5]. Cortisol changed by −6.6% during rest, +5.7% at 40%, +39.9% at 60% and +83.1% at 80% [5]. The authors attributed the increases to a combination of haemoconcentration and HPA-axis stimulation through ACTH [5]. After correction for plasma volume and circadian factors, the low-intensity 40% session actually reduced circulating cortisol [5].
This matters for everyone who exercises, and it is central to the athlete section below. A cortisol rise after a hard session is an expected response [5].
How to Lower Cortisol: What the Evidence Supports
Four strategies have research behind them, but the strength of the evidence differs: exercise and ashwagandha have trial and meta-analytic data, meditation has meta-analytic data with mixed results, and the sleep evidence mostly describes the harm of sleep loss. Each has limits worth knowing.
1. Regular physical activity, mostly light to moderate
In the 2022 meta-analysis, the cortisol result came from 651 adults [1]. Exercise programmes were associated with lower cortisol than usual care or active controls (SMD −0.37), and aerobic programmes and mind-body programmes such as yoga did not differ significantly from each other (p = .50) [1]. The same review found low-certainty evidence that exercise improved sleep quality scores (SMD −0.30) [1].
The population limits generalisation. Of the nine meta-analysed studies, six included solely breast cancer patients, only 10% of participants were male, and no trials included adults aged 65 or older [1]. The authors concluded that light-to-moderate exercise, whether aerobic or mind-body, seems beneficial for both stress and sleep [1]. That fits the exercise-intensity study above, where 30 minutes at 40% of VO₂max lowered cortisol once plasma volume and circadian factors were accounted for [5].
2. Meditation and mindfulness, especially under real stress
A 2021 meta-analysis asked whether meditation lowers cortisol more in people at risk of elevated cortisol [3]. In 10 studies using blood samples, meditation had a significant, medium-sized effect compared with control groups, but only in at-risk samples, namely patients with a somatic illness [3]. In 21 studies using saliva samples, the effect was small and not statistically significant, with a marginally significant effect in groups living in stressful life situations [3].
An earlier meta-analysis of randomised controlled trials compared meditation with active control groups rather than doing nothing [11]. Focused-attention meditation reduced cortisol, and when all meditation types were analysed together, meditation reduced cortisol, C-reactive protein, blood pressure, heart rate, triglycerides and tumour necrosis factor-alpha [11].
In short, the blood-cortisol effect appeared in at-risk samples and the saliva-based effect was small and not statistically significant [3]. Meditation may therefore be a reasonable tool when stress is genuinely high, but these data do not show a reliable cortisol-lowering effect in people without elevated risk.
3. Protect sleep duration and timing
The sleep studies above show what sleep loss does: two nights of 4 hours in bed raised evening cortisol and flattened its daily decline [2], and pooled data show higher cortisol after acute sleep deprivation when serum or repeated measurements were used [10]. Most of this evidence describes the harm of sleep loss rather than testing extra sleep as a cortisol treatment, but because short sleep disturbed cortisol timing in the controlled experiment [2], protecting sleep is a reasonable precaution rather than a tested treatment.
4. Ashwagandha: promising evidence, with caveats
A 2026 meta-analysis of 23 randomised, placebo-controlled trials with 1,706 participants found that ashwagandha significantly reduced cortisol (SMD −1.18, p < 0.04) [12]. It also increased testosterone in men (mean difference 57.43 ng/dL) but the change in women was not statistically significant, and the authors noted that heterogeneity and limited data on some endpoints call for further standardised trials [12].
A separate 2025 meta-analysis included seven trials on cortisol and six on perceived stress (n = 488) [4]. Included trials lasted at least two weeks and used oral doses of at least 250 mg/day [4]. Cortisol fell by 1.16 µg/dL (95% CI −1.64 to −0.69), but there was no significant effect on Perceived Stress Scale scores (SMD −0.355; P = 0.40), and the author highlighted gaps in long-term safety, dosing and effectiveness across diverse populations [4]. The two analyses report effects on different scales (standardised mean difference versus µg/dL), so their figures are not directly comparable.
A lower cortisol value on paper therefore did not translate into a significant change in perceived stress [4].
In My Clinic: Start With the Source of the Stress
In my practice, we often refer patients to a psychologist early on, because a psychologist can help with problem solving and with cognitive methods that change how stress is approached. From a clinical perspective, a stressor often stops being stressful once it is actually resolved; the stress of a thesis, for example, ends when the thesis is finished. There is rarely a way around this. The situations I find hardest are those that cannot be resolved because they are outside the patient’s control, since the patient keeps looking for a solution that is not available, which is itself very stressful.
When workload is the cause, sick leave can sometimes be the clearest option. In my experience, patients may be on sick leave for several weeks and occasionally for several months, depending on how long stress has been elevated, and this often lowers stress and helps recovery. It is nevertheless a fairly extreme measure. My first priority is to try to keep the person in their own role with a lighter workload, and to take temperament into account: someone who is easily disturbed may do better with a room of their own, while a very social person may cope better in a group where they can talk with colleagues than working alone.
In many situations I recommend good sleep, healthy habits and regular exercise, which fits the evidence on sleep and physical activity above. Education about stress, which is also a central part of psychotherapy, is in my view of primary importance in reducing it. The strategies above are the ones with trial data behind them; the points in this section are clinical starting points rather than trial-tested interventions.
Testing Cortisol: What a Result Can and Cannot Tell You
Cortisol follows a daily rhythm [1], so a single value is a snapshot. In research, an accepted sampling design uses several samples across the day, for example immediately after waking, 30 minutes after waking, at noon, in the late afternoon and just before bed [1]. The sleep-deprivation meta-analysis above illustrates why: effects were detectable in studies with multiple measurements but not in studies that relied on a single cortisol assessment [10].
Timing around exercise matters too. Because moderate-to-hard exercise raises circulating cortisol [5], a sample taken soon after a hard session may tell you more about that session than about your baseline. For athletes, resting cortisol is also a weak tool for detecting overtraining, as discussed below [8].
Patients sometimes ask me whether it is worth testing their cortisol. In my clinical experience, testing is of limited use in this situation, for several reasons. A single value is hard to interpret, because cortisol varies with time of day, sleep and recent exercise, and we usually do not know the patient’s baseline. In a patient with nonspecific stress complaints, even an elevated value would not by itself lead to any particular measures.
When high cortisol needs a doctor, not a lifestyle fix
Endogenous Cushing’s syndrome, in which the body itself produces excess cortisol, is a rare disease [13]. It is usually characterised by hypertension, diabetes, obesity, osteoporosis, a rounded face, a fat pad at the back of the neck, thin skin, purple stretch marks (striae), excess hair growth (hirsutism) and mood disorders [13].
For screening, Endocrine Society guidance recommends choosing one of four tests according to the patient: the 1 mg overnight dexamethasone suppression test, the longer low-dose dexamethasone suppression test, late-night salivary cortisol or 24-hour urinary free cortisol [14]. Salivary and urinary cortisol need at least two measurements, and an abnormal result should be followed by evaluation by an endocrinologist [14]. Late-night saliva is useful because cortisol normally reaches its lowest point shortly after falling asleep, whereas people with Cushing’s syndrome have higher night-time values [13]. Every screening test has pitfalls: some drugs interfere with the dexamethasone test, saliva samples can give false results, and antibody-based immunoassays can produce false positives through cross-reactivity with related steroids [13].
If several of those features apply to you, the right next step is a medical assessment. Meditation apps and supplements are not a substitute for ruling out a hormonal disorder.
In basic differential diagnostics we do measure cortisol from time to time, but not in the sense that patients often have in mind. If Cushing’s syndrome is suspected, measuring cortisol is appropriate. As a marker of exhaustion, stress or burnout, however, I do not find it a usable value, and it is not part of the basic laboratory panel. In my clinical experience, an elevated value without other findings pointing to a hormonal disorder does not usually call for special measures. Interpretation always depends on the test used, the sampling conditions and the clinical picture.
What It Means for Athletes: How to Lower Cortisol Without Undermining Training
For athletes the question changes. Hard sessions raise cortisol [5], so the aim is not to suppress that response. A more useful question is whether avoidable stressors such as under-fuelling [7] or short sleep [2] are adding to it.
Expect cortisol to rise after hard sessions
In the intensity study described earlier, 30 minutes at 60% and 80% of VO₂max raised cortisol by 39.9% and 83.1%, respectively [5]. Reviewers of the carbohydrate literature note that stress hormones play an essential role in allocating energetic resources, orchestrating immune surveillance and adapting cardiac output to the physical load [6].
Fuel long endurance sessions
A 2024 systematic review included 11 placebo-controlled studies in experienced endurance athletes, with 159 participants in total, eight of the studies including men only [6]. Exercise lasted one to four hours at 60–85% of VO₂max, and eligibility required at least 30 g of carbohydrate per hour, ingested no more than 30 minutes before exercise started, with a placebo-controlled design [6]. Nine of the 11 studies reported a significant group-by-time interaction for cortisol, which the authors interpreted as lower cortisol after exercise with carbohydrate than with placebo, and they concluded that 50–100 g per hour taken continuously during prolonged exercise was effective in reducing HPA-axis activation in their included studies [6].
Eat enough to cover your training
In a randomised, single-blinded crossover study, 12 female endurance athletes spent 14 days on a low energy availability diet (22 ± 2 kcal per kg fat-free mass per day) and 14 days on an optimal diet (52 ± 2 kcal per kg fat-free mass per day) [7]. Low energy availability increased systemic cortisol by 22% (P = 0.013) [7]. Performance fell in both exercise tests, and the drop in time-trial performance persisted after three days of refuelling [7].
This study included women only, so the size of the effect in male athletes is not known from these data. The direction is still a useful warning: in this study, 14 days of low energy availability raised cortisol.
A growth mindset and sport psychology
Athletes in particular may benefit from a consultation with a sport psychologist, and developing a growth mindset is one reason. In my own athletic career it made a real difference: I did not have to perform every time, and if I did not win, I at least knew that I would learn something. My own stress decreased noticeably once I had developed a growth mindset. It can be harder to apply at work, but in my view the principles are the same in sport and in everyday life. For me it was a decisive way to reduce stress, along with seeking out environments where I stress less, and that has been my coping approach in both working life and sport.
Do not diagnose overtraining from one cortisol value
A systematic review of 38 studies found that basal hormone levels, including cortisol, were mostly normal in athletes with overtraining syndrome or overreaching compared with healthy athletes [8]. Resting cortisol after deliberate overload training was normal in 75.0% of findings across 16 studies, and cortisol responses to stimulation tests were conflicting [8]. The authors concluded that basal hormone levels are not good predictors of these conditions [8].
I cover how cortisol behaves under stress in overtrained athletes, and why resting tests often look reassuring, in Cortisol and Overtraining.
In an athlete’s blood work, I find that a cortisol value on its own tells us very little. If we knew the athlete’s baseline over a longer period, a value might add a little, but even a mildly elevated result, or one rising from baseline, is not very informative. The cortisol awakening response could in principle be used in some situations, but in practice I do not see it used in clinical work; it remains more of a research-level curiosity. For these reasons, I would not give cortisol testing a special status in athletes compared with sedentary people. The indications are the same: clinical, and aimed at ruling out disease rather than optimizing performance.
How to Lower Cortisol: Practical Steps
For everyone
- Make regular light-to-moderate activity the foundation. Both aerobic and mind-body programmes had trial support for lowering cortisol [1].
- Protect sleep and avoid repeated very short nights. Two nights of 4 hours in bed raised evening cortisol and flattened its daily decline [2].
- Consider meditation during stressful periods. Effects on blood cortisol were clearest in at-risk groups [3], and focused-attention meditation reduced cortisol against active controls [11].
- Discuss ashwagandha with a doctor before using it. Cortisol fell in pooled trials, but perceived stress did not change significantly and long-term safety data remain limited [12][4].
- Seek medical assessment, not a supplement, if you have features of genuine cortisol excess such as hypertension, diabetes, purple stretch marks or a rounded face [13].
For athletes
- Do not aim to eliminate the cortisol response to hard sessions. It rises with exercise intensity [5], and stress hormones play an essential role in adapting to physical load [6].
- Take carbohydrate during long endurance sessions. In studies using at least 30 g per hour, carbohydrate attenuated cortisol rises in most cases [6].
- Match energy intake to training load. Fourteen days of low energy availability raised cortisol by 22% and impaired performance in female endurance athletes [7].
- Judge overtraining by performance, symptoms and training history rather than by a single resting cortisol value [8].
Conclusion: How to Lower Cortisol Without Chasing a Number
The research on how to lower cortisol is real, but the effects vary in size and certainty. Exercise programmes lowered cortisol with a pooled SMD of −0.37 [1], meditation had its clearest effect in people at risk of elevated cortisol [3], and ashwagandha lowered cortisol by 1.16 µg/dL without a significant change in perceived stress [4].
For athletes, the levers with trial support here are unglamorous ones. Carbohydrate during long sessions blunted cortisol rises in most trials [6], and two weeks of under-fuelling raised cortisol by 22% while impairing performance [7].
In my clinical experience, the most useful starting point for prolonged stress is the source of the stress itself. Stressors often ease once they are actually resolved, and where they cannot be, it can help to lighten the workload and to take the person’s temperament into account. A cortisol test is rarely the answer: in my view the indications are the same for athletes and non-athletes, namely to rule out disease rather than to optimize performance. For me personally, a growth mindset was a decisive stress reducer, both in sport and in working life.
Move regularly, sleep enough, eat enough for your training, and treat cortisol as a signal to understand rather than an enemy to defeat.
Bibliography
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[3] https://doi.org/10.1080/17437199.2020.1760727
[4] https://doi.org/10.1177/02601060251363647
[5] https://doi.org/10.1007/BF03345606
[6] https://doi.org/10.3389/fspor.2024.1264814
[7] https://doi.org/10.1016/j.redox.2024.103250
[8] https://doi.org/10.1186/s13102-017-0079-8
[9] https://doi.org/10.1016/j.psyneuen.2017.05.018
[10] https://doi.org/10.1507/endocrj.EJ23-0714
[11] https://doi.org/10.1016/j.jpsychires.2017.08.004
[12] https://doi.org/10.1055/a-2802-8363
