Cortisol
In brief
Section titled “In brief”- Cortisol is essential for energy, blood pressure, immune function and day-night rhythm
- The goal is not “cortisol down” but a healthy pattern
- Problems arise with too high cortisol in the evening or chronically high
- First focus on rhythm, sleep and recovery - testing is rarely the first step
- Signals are not specific: optimize lifestyle before measuring
What is cortisol?
Section titled “What is cortisol?”Cortisol is made by the adrenal glands under control of the brain (hypothalamus and pituitary). It helps the body handle stress and maintain internal balance.
The normal day-night rhythm
Section titled “The normal day-night rhythm”| Time | Cortisol level |
|---|---|
| 30-45 min after waking | Rises (cortisol awakening response) |
| During the day | Gradually declining |
| Evening and night | Low |
What cortisol does
Section titled “What cortisol does”- Keeps energy and blood sugar stable between meals and during fasting
- Supports fat and protein metabolism when extra energy is needed
- Inhibits excessive inflammation and directs immune responses
- Helps keep blood pressure and circulation stable
- Supports alertness and focus, especially in the morning
When cortisol becomes a problem
Section titled “When cortisol becomes a problem”- Too high late in the evening or around 3:00 AM can disrupt sleep
- Chronically high (weeks/months) can impair recovery and cause unrest
- Irregular life keeps the system more easily “on”:
- Sleep deprivation
- Night work
- Alcohol
- Overtraining
- Undereating
Signals that may fit
Section titled “Signals that may fit”- Difficulty falling asleep, frequent waking, or early waking with “on” feeling
- Tired during the day and more energetic in the evening
- Restlessness, tense body, irritability
- Much need for caffeine or snacking
- Dizziness when standing up (has multiple causes)
Practical approach: focus on rhythm
Section titled “Practical approach: focus on rhythm”Choose 2-3 points and implement them consistently for 2-4 weeks.
Morning
Section titled “Morning”- Fixed wake time, also on weekends (small deviation is fine)
- Outside for daylight within 30 minutes
Evening
Section titled “Evening”- Last 1-2 hours dim light and limit screens
- Clear the head: short note with to-do’s and worries
Caffeine
Section titled “Caffeine”- No caffeine after 12:00-14:00
- If sensitive: coffee only after light, water and possibly breakfast
Movement and training
Section titled “Movement and training”- Daily walking (preferably outside)
- Heavy training preferably earlier in the day and with sufficient recovery
Nutrition and electrolytes
Section titled “Nutrition and electrolytes”- Choose a pattern that keeps your energy stable
- With TKB/KMT: pay attention to sufficient protein, energy, salt and fluids
Stressors concrete
Section titled “Stressors concrete”Metabolic and mental
Section titled “Metabolic and mental”Blood sugar fluctuations can cause unrest, irritability and energy dips. With less fluctuation, many people experience more stable energy and mood.
Ketones are an alternative fuel for the brain. Some people experience more focus or mental calm when they (temporarily) enter nutritional ketosis.
Testing cortisol
Section titled “Testing cortisol”Why a single measurement often says little
Section titled “Why a single measurement often says little”Cortisol varies by hour and reacts to:
- Sleep and stress
- Illness and pain
- Exertion
- Alcohol and caffeine
The result is therefore only meaningful if test type and timing are correct.
What question do you want to answer?
Section titled “What question do you want to answer?”| Question | Suspicion |
|---|---|
| Too much cortisol? | Cushing’s |
| Too little cortisol? | Adrenal insufficiency or suppression by corticosteroids |
Timing is crucial
Section titled “Timing is crucial”- Morning values belong to your wake time
- Evening/night should be low - a high value needs context
- Shift work/jet lag makes interpretation more difficult
Which tests are used
Section titled “Which tests are used”| Test | Application |
|---|---|
| Blood (morning cortisol) | First impression, sometimes follow-up test needed |
| Saliva late evening | For suspicion of too much cortisol |
| 24-hour urine | Total production over 24 hours (correct collection is essential) |
| Dexamethasone suppression test | Checks if cortisol can be normally suppressed |
| ACTH stimulation test (Synacthen) | Assesses adrenal reserve for suspicion of too little cortisol |
What can distort the result
Section titled “What can distort the result”- Poor sleep, acute stress, pain, infection/inflammation
- Intensive training, alcohol (especially late), caffeine just before collection
- Medication - especially all forms of corticosteroids (tablet, inhalation, nasal, skin, injection)
- Hormonal factors (e.g. estrogens) and other medication interactions
Practical preparation
Section titled “Practical preparation”Always follow the lab instructions. In general, it helps to:
- No extreme exercise 24-48 hours beforehand
- Avoid alcohol
- Start the morning of collection calmly
- Only adjust medication in consultation
When testing is useful
Section titled “When testing is useful”- For alarm signals or clear clinical suspicion
- For complaints around tapering/stopping corticosteroids
- For unexplained fainting, severe dizziness, prolonged vomiting or unexplained weight loss
- For features fitting Cushing’s (in consultation with doctor)
Veelgestelde vragen
What is cortisol?
Cortisol is an essential hormone, made by the adrenal glands under brain control. It helps the body handle stress and keeps energy, blood pressure and immune function stable. The goal is usually not 'cortisol down', but a healthy pattern: higher in the morning, declining during the day, low in the evening.
When does cortisol become a problem?
Too high cortisol late in the evening or around 3:00 AM can disrupt sleep. Chronically high cortisol (weeks/months) impairs recovery. An irregular life with sleep deprivation, night work, alcohol, overtraining or undereating keeps the system more easily 'on'.
Should I have my cortisol tested?
For general stress or fatigue complaints, testing is rarely the best first step. First optimize rhythm, sleep and load-capacity balance. Testing is useful for alarm signals, suspicion of Cushing's or adrenal insufficiency, or for complaints around tapering corticosteroids.
Why does a single cortisol measurement often say little?
Cortisol varies by hour and reacts to sleep, stress, illness, pain, exertion, alcohol and caffeine. The result is only meaningful if test type and timing are correct. Morning values belong to your wake time, evening/night should be low.
What can I do myself for a healthy cortisol rhythm?
Focus on rhythm: fixed wake time, outside for daylight within 30 minutes, no caffeine after 12:00-14:00, dim light in the evening, daily walking, and heavy training preferably earlier in the day. Choose 2-3 points and implement them consistently for 2-4 weeks.
Medische Disclaimer: De informatie van Stichting Je Leefstijl Als Medicijn over leefstijl, ziektes en stoornissen mag niet worden opgevat als medisch advies. In geen geval adviseren wij mensen om hun bestaande behandeling te veranderen. We raden mensen met chronische aandoeningen aan om zich over hun behandeling goed door bevoegde medische professionals te laten adviseren.
Medical Disclaimer: The information provided by Stichting Je Leefstijl Als Medicijn regarding lifestyle, diseases, and disorders should not be construed as medical advice. Under no circumstances do we advise people to alter their existing treatment. We recommend that people with chronic conditions seek advice regarding their treatment from qualified medical professionals.