Cortisol gets a bad reputation as “the stress hormone,” but your body depends on healthy cortisol output for energy, immune function, blood-sugar regulation, and dozens of other daily processes. For people with genuinely low cortisol, whether from burnout, adrenal insufficiency, chronic fatigue states, or simply a blunted morning cortisol response, the question of how to push levels back up naturally is legitimate and under-discussed. Research points to several practical strategies, from timed light exposure and exercise intensity to specific dietary choices and even heat stress, each working through different arms of the hormonal system that governs cortisol production.
Morning Light Exposure and the Cortisol Awakening Response
Cortisol follows a sharp daily rhythm: it surges in the first 30 to 45 minutes after you wake up, a phenomenon researchers call the cortisol awakening response, or CAR. This surge sets the tone for alertness and metabolic activity throughout the day. One of the most reliable ways to amplify it is exposure to bright or blue-enriched light shortly after waking. In controlled studies of healthy men, bright light exposure in the post-awakening period significantly increased the CAR compared to dim light, with blue and green wavelengths producing a stronger effect than red light.1PubMed. The effects of post-awakening light exposure on the cortisol awakening response in healthy male individuals A separate study confirmed that both bright white light and blue light raised morning salivary cortisol compared to dim and red light conditions, with the effect running through stimulation of the body’s central stress axis.2PubMed. Increase in cortisol concentration due to standardized bright and blue light exposure on saliva cortisol in the morning following sleep laboratory
In practical terms, this means getting outside into natural daylight within 30 minutes of waking, or using a bright light box if you wake before sunrise. The mechanism is straightforward: light signals reach the brain’s central clock, which in turn tells the adrenal glands to ramp up cortisol production. This central pacemaker drives the entire 24-hour cortisol pattern and acts as the master synchronizing signal that coordinates metabolism across the body.3PubMed Central. Sleep and Circadian Regulation of Cortisol: A Short Review If your morning cortisol feels sluggish, a dim bedroom followed by immediate bright light is one of the simplest interventions available.
Why Sunrise Time and Season Matter
If you have noticed feeling more alert and energized in winter mornings despite shorter days, cortisol may be part of the explanation. A large population study found that median cortisol was lowest in summer and highest in winter, and that sunrise time was a better predictor of cortisol variation than the season label itself. For each hour that sunrise was delayed, median cortisol increased by about five percent.4PubMed. The effects of season, daylight saving and time of sunrise on serum cortisol in a large population The interpretation is that when the sun rises later, your body compensates with a stronger cortisol push to get you going in relative darkness.
Interestingly, a study measuring salivary cortisol across seasons found higher overall cortisol in summer, with the peak shifted about four hours later compared to winter.5PubMed. Seasonal differences in rhythmicity of salivary cortisol in healthy adults These two studies measured cortisol differently (blood draws versus saliva, single time-point versus 24-hour rhythm), which helps explain the apparent disagreement. The unifying takeaway is that your cortisol rhythm is tightly linked to when you see light, and manipulating that timing with bright morning exposure can shift the pattern in the direction you want.
Exercise Intensity Is the Key Variable
Exercise reliably raises cortisol, but only if the effort is hard enough. A study that tested sessions at rest, 40%, 60%, and 80% of maximal aerobic capacity found a clear threshold effect. Low-intensity work at 40% barely budged cortisol above resting levels. At 60% intensity, cortisol rose by about 40% from baseline, and at 80%, it climbed by roughly 83%.6PubMed. Exercise and circulating cortisol levels: the intensity threshold effect Gentle walking or light yoga, in other words, is unlikely to move the needle on cortisol production. You need to be breathing hard.
High-intensity interval training shows a similar pattern. In soccer athletes performing a high-intensity exercise protocol, salivary cortisol rose significantly from pre-test levels.7PubMed. Acute high-intensity exercise test in soccer athletes affects salivary biochemical markers And in a study tracking hormonal responses to repeated high-intensity sessions, the initial bout produced acute increases in cortisol, prolactin, and thyroid-stimulating hormone.8PubMed. Acute and delayed hormonal and blood cell count responses to high-intensity exercise before and after short-term high-intensity interval training For someone trying to raise cortisol, incorporating two or three vigorous exercise sessions per week at moderate-to-high intensity is a well-supported approach.
The Overtraining Trap
There is a paradox here that catches people off guard. While intense exercise acutely raises cortisol, chronically overdoing it can have the opposite effect. Athletes who push into overtraining syndrome end up with blunted cortisol and ACTH responses to physical stress. During positive training adaptation, cortisol rises in response to exercise as expected. During overreaching, the cortisol response starts to flatten. In full-blown overtraining syndrome, both ACTH and cortisol responses to exercise are diminished, and early-morning cortisol levels drop to their lowest.9Sports Medicine and Health Science. Beyond physical exhaustion: Understanding overtraining syndrome through the lens of molecular mechanisms and clinical manifestation – Section: Neuroendocrine system, hormones, neurotransmitters, growth factors, and brain functions
A systematic review of hormonal changes in overtraining confirmed that stimulation tests, particularly those using maximal exercise, showed blunted hormonal responses in overtrained athletes, though cortisol findings specifically were more mixed than growth hormone or ACTH findings.10PubMed Central. Hormonal aspects of overtraining syndrome: a systematic review If you are someone with already-low cortisol who has been exercising relentlessly in hopes of “fixing” it, the exercise itself may be part of the problem. Recovery days are not optional, they are part of the hormonal stimulus.
Carbohydrates, Calories, and Cortisol
Food is a powerful timekeeper for cortisol. Meal timing and composition both influence how much cortisol your body produces and when. Feeding is considered one of the strongest non-light signals that synchronizes the body’s peripheral clocks and shapes daily cortisol output.11PubMed Central. “Feeding the Rhythm”-Effects of Food and Nutrients on Daily Cortisol Secretion: From Molecular Mechanisms to Clinical Impact
Among macronutrients, carbohydrates stand out. A study comparing identical-calorie meals of pure protein, pure fat, and pure carbohydrate found that cortisol concentrations dropped after the protein and fat meals but were maintained after the carbohydrate meal. The cortisol response following carbohydrate intake was significantly higher than in a fasting control condition, while protein and fat meals produced cortisol levels no different from skipping a meal entirely.12PubMed. Effects of single macronutrients on serum cortisol concentrations in normal weight men For someone trying to support cortisol levels, this suggests that very-low-carb or ketogenic diets could be working against that goal.
An intervention study that shifted participants toward a dietary pattern higher in carbohydrates found that the greatest increases in carbohydrate intake were linked to a dampening of the stress cortisol response over eight weeks, which sounds like the opposite of what you want. But the context matters: that study was measuring cortisol reactivity to a psychological stressor, not baseline cortisol levels.13PubMed Central. Increasing Dietary Carbohydrate as Part of a Healthy Whole Food Diet Intervention Dampens Eight Week Changes in Salivary Cortisol and Cortisol Responsiveness The practical distinction: carbohydrates help maintain resting cortisol output through the day, but over time a healthy, carb-inclusive diet may reduce the spiky cortisol surges that come from acute stress. Both effects can be useful depending on your situation.
Caloric intake in general has its own effect. A study measuring cortisol during both 10 days of overfeeding and 10 days of fasting found that both extremes increased total and free cortisol levels.14PubMed Central. Changes in serum cortisol levels after 10 days of overfeeding and fasting This is not a recommendation to overeat or starve yourself, but it does illustrate that cortisol responds to caloric stress in both directions. Chronic undereating, which is common in people with fatigue-related conditions, can disrupt cortisol rhythms in unpredictable ways.
Sodium Intake and Cortisol
Salt restriction, often considered universally healthy, has a measurable effect on cortisol. A study comparing restricted versus liberalized sodium intake found that 24-hour urinary free cortisol, a measure of the body’s total cortisol production through the day, increased from about 121 to 178 nmol/day when sodium was liberalized, and roughly 84% of participants showed an increase.15PubMed Central. Dietary Sodium Intake and Cortisol Measurements This does not mean you should eat salt by the spoonful, but if you already have low cortisol and are on a very strict low-sodium diet, it may be worth discussing with your doctor whether moderate sodium intake could support your cortisol output.
Caffeine Raises Cortisol, but Tolerance Builds Fast
Caffeine is one of the most potent acute cortisol stimulants available without a prescription. After five days of complete caffeine abstinence, a caffeine dose produced a robust cortisol increase that lasted across the entire waking day. But after just five days of regular caffeine intake at 300 mg per day (roughly three cups of coffee), the cortisol response to the morning dose was completely abolished. A second dose later in the day did still produce some cortisol elevation, and higher daily intake at 600 mg showed a similar pattern of partial tolerance.16PubMed Central. Caffeine Stimulation of Cortisol Secretion Across the Waking Hours in Relation to Caffeine Intake Levels
The practical implication is counterintuitive: if you want caffeine to help raise cortisol, habitual use actually works against you. Intermittent caffeine use, with periodic breaks of several days, preserves its cortisol-stimulating effect. Daily coffee drinkers have largely adapted to caffeine’s hormonal effects, which is one reason that “morning coffee to wake up” may not be doing what you think it is doing on the cortisol front.
Sauna and Heat Exposure
Heat stress triggers a cortisol response through many of the same pathways as exercise. A study of Finnish sauna bathing found that a single session caused significantly elevated blood cortisol levels in both athletes and non-athletes.17PubMed Central. Effect of a Single Finnish Sauna Session on White Blood Cell Profile and Cortisol Levels in Athletes and Non-Athletes Post-exercise infrared sauna use also raised cortisol the following morning after the first session, though this effect faded with repeated sessions.18PubMed Central. Salivary cortisol response to post-exercise infrared sauna declines over time
The evidence is not entirely consistent, though. A review of sauna studies noted that findings on acute cortisol effects are variable: some studies show an increase, some show an initial dip followed by a rise, and some report no change at all.19Current Opinion in Endocrine and Metabolic Research. Endocrine effects of sauna bath – Section: Cortisol The discrepancy probably comes down to how long and how hot the session was, whether the person was a habitual sauna user, and whether they exercised beforehand. As with caffeine, habituation seems to blunt the cortisol response over time. Occasional rather than daily heat exposure is more likely to produce a meaningful hormonal effect.
Licorice Root and Cortisol Metabolism
This one works through a completely different mechanism than everything else on this list. Licorice root contains glycyrrhizin, which gets metabolized into glycyrrhetic acid in the body. This compound blocks an enzyme that normally converts active cortisol into its inactive form, cortisone. The result is that cortisol sticks around longer and exerts stronger effects, particularly on mineral balance, raising sodium retention and lowering potassium levels.20PubMed Central. Licorice abuse: time to send a warning message
This sounds appealing for someone with low cortisol, and small amounts of whole licorice root tea have been used in traditional medicine for exactly this purpose. But the same mechanism that makes it effective also makes it dangerous at higher doses. Chronic licorice consumption can push sodium up and potassium down to levels that cause high blood pressure, muscle weakness, and heart-rhythm problems. The source on this topic is literally titled “Licorice abuse: time to send a warning message.” Deglycyrrhizinated licorice (DGL), which is the form sold for digestive complaints, has had the active compound removed and will not affect cortisol. If you want the cortisol effect, you need the regular form, but you should discuss it with a doctor first, especially if you have any cardiovascular risk factors.
Sleep Restriction and Circadian Disruption
Sleep and cortisol have a complicated relationship. Substantial sleep restriction raises cortisol in the late afternoon and evening, but it does not increase total 24-hour cortisol; it merely shifts the timing. Acute circadian misalignment, like what happens with jet lag or shift work, only slightly delays the cortisol rhythm. But prolonged circadian misalignment actually decreases overall cortisol exposure.3PubMed Central. Sleep and Circadian Regulation of Cortisol: A Short Review
This means that sleeping less is not a viable strategy for raising cortisol in any useful way. You get cortisol at the wrong time (evening, when you want it low) and lose it at the right time (morning, when you need it high). And chronic circadian disruption makes everything worse. The research reinforces a consistent theme: aligning your internal clock through consistent wake times, morning light, and regular meal timing does more for cortisol output than any single supplement or trick.
When Low Cortisol Needs Medical Attention
The strategies above are reasonable for people whose cortisol is on the low side of normal or who want to optimize a sluggish morning response. They are not a substitute for medical treatment of genuine adrenal insufficiency, which is a potentially life-threatening condition requiring hormone replacement under clinical supervision.
One condition that blurs the line is burnout-related hypocortisolism. A study comparing patients with varying severity of burnout found that those with higher burnout scores had significantly lower salivary cortisol responses to acute psychological stress than controls. The cortisol response in the most burned-out group was roughly a third of the response seen in the control group.21Frontiers in Psychiatry. Burnout and Hypocortisolism – A Matter of Severity? A Study on ACTH and Cortisol Responses to Acute Psychosocial Stress This kind of cortisol flattening is thought to be the body’s adaptation to chronic stress overload, essentially a protective downregulation that goes too far.
If you suspect your cortisol is genuinely low, a morning blood cortisol test or a more detailed stimulation test through an endocrinologist can clarify where you stand. The natural strategies discussed here can complement clinical treatment, but they work best as part of a broader plan that addresses the root cause of the suppression, whether that is chronic overexertion, sleep disruption, caloric restriction, or prolonged psychological stress.
Adaptogens and the Limits of the Evidence
Herbal adaptogens like ashwagandha, rhodiola, and various ginseng preparations are widely marketed for “adrenal support,” and there is a preliminary scientific basis for the concept. A review of adaptogen research described these compounds as working through the immune-neuroendocrine system and the HPA axis in a broad, non-specific way to enhance the body’s resistance to external stress.22PubMed Central. A preliminary review of studies on adaptogens: comparison of their bioactivity in TCM with that of ginseng-like herbs used worldwide The word “non-specific” is doing a lot of work there. Adaptogens do not simply raise or lower cortisol; they are thought to modulate the stress response depending on the direction it needs to go, which makes them tricky to study and even trickier to recommend with confidence for someone whose specific goal is higher cortisol output.
Most clinical trials on adaptogens have measured stress perception, fatigue, or mood rather than cortisol levels directly. The ones that have measured cortisol often show a reduction, which is the opposite of what someone with low cortisol wants. This is a space where the marketing has outpaced the science. If you are considering adaptogens, know that the evidence for them as cortisol-raising agents specifically is thin, and their effects probably depend heavily on your baseline stress physiology. The light, exercise, and dietary strategies covered earlier have a much clearer evidence base for moving cortisol in a specific direction.