The Melatonin-Cortisol hormone correlation

Melatonin is a rarely discussed – or understood – hormone that is indispensable to our health and quality of life. Melatonin is a neuropeptide (form of amino acid) secreted principally by the pineal gland in the brain.

Melatonin’s role is to regulate circadian rhythm and induce sleep cycles. It also aids temperature regulation and some hormone cycles. Melatonin secretion is stimulated by darkness and having one’s eyes closed but not being asleep.

Melatonin operates in-rhythm with the Adreno-corticoid hormone Cortisol (CC). In simple terms Cortisol peaks in its diurnal rhythm in the morning – and correspondingly decreases Melatonin levels – to awaken us from sleep. Cortisol gradually decreases over the day (the CC diurnal rhythm); reaching its lowest level in the late evening. Melatonin again begins to rise – and we go to sleep.

Persons suffering ‘Adrenal Fatigue’ exhibit a ‘flattened’ – or even inverted Cortisol profile where ‘morning surge’ is absent but occurs in the late evening. An ‘inverted’ CC diurnal profile will tend to suppress Melatonin – leading to sleep, mood – and ultimately health disturbance.

Humans produce highest levels of Melatonin in childhood – but levels tend to diminish with age.

Melatonin is regarded as the body’s most crucial anti-ageing hormone (Rebic: 2010); a powerful anti-oxidant, central to immune system integrity – particularly in the prevention of cancer in hormone sensitive tissue (Baratosy: 2010). Melatonin also exerts an analgesic (opioid-like) effect on the body in chronic pain or inflammatory disease states (Hertoghe: 2006) and helps overcome ‘jet lag’.

Melatonin positively influences the effects of our hormones; helping to raise Human Growth Hormone (HGH) and thyroid hormone levels (by increasing T4 – T3 conversion). Adequate levels of Melatonin play a crucial role in reducing disturbance of mood such as depression and anxiety.

Sleep deprivation or interference in natural circadian rhythm for sustained periods of time will severely impact on our health, immediate quality of life – and longevity. Accelerated ageing, hormonal and metabolic disturbance – such as diabetes, obesity, hypertension; lethargy, lowered immunity, body aches + pains, impaired mental function and hair loss are some of the problems that arise from sleep deprivation and its consequences.

The most restful recovery sleep is between the hours of 9pm to 1am – termed ‘Delta Phase’ (Hywood: 2009). ONE hour of sleep during this period is equal to TWO hours sleep after 1am.

The body’s physical repair occurs from 9/10pm to 2am, whilst immune system and psychological recovery happen between the hours of 2am-6am. Severe headaches and mood disorders may result from lack of sleep through these early morning hours (Rebic: 2010).

How to optimise Melatonin secretion:

  • Develop a good sleep routine – aim to be in bed in a darkened room by 10pm.
  • Avoid eating heavy (rich or fatty) meals before bedtime as Cortisol levels – which suppress Melatonin secretion – temporarily triple after eating.
  • Avoid alcohol, cigarette smoking, caffeine or other stimulant drugs – alcohol and caffeine both inhibit/suppress Melatonin secretion.
  • Avoid strenuous physical exercise or activities in the late afternoon or evening (particularly).
  • Minimise evening exposure to Electromagnetic Radiation (EMR) – power lines, mobile telephones, blue-white fluorescent lighting, electrical appliances such as microwave ovens, televisions, computers, powered alarm clock/radios, personal music devices etc.

It is said we are now exposed to more EMR in one DAY than those living 50-100 years ago were exposed to in one YEAR … Numerous studies show a direct correlation between EMR exposure and Melatonin suppression (Baratosy: 2010).

Foods that enhance Melatonin production:

Because Tryptophan is the precursor of Melatonin (i.e.: synthesised or ‘made from’) – foods which are naturally high in Tryptophan will aid the body’s exogenous Melatonin supply. Some of these foods are chicken, turkey, bananas and milk.

Supplements: certain supplements such as Fish Oils (EPA/DHA) exert Melatonin-like properties. St. John’s Wort can stimulate Melatonin secretion, whilst herbs such as Withania indirectly increase Melatonin by calming excessive Cortisol activity and help in overcoming insomnia. (L)-Tyrosine amino acid is the precursor of Tryptophan – which is then the precursor of Melatonin (as referred to above).

According to Chan (2015) compounded prescription sub-lingual Melatonin drops are most effectively utilised by the body. Melatonin is considered a ‘master hormone’ (Chan: 2016) that can profoundly influence other hormones & glands; as such it should always be prescribed & supervised by a Practitioner experienced in hormone therapies.


  1. Melatonin Profile via Salivary Assay is the most reliable method of testing. Due to its circadian rhythm, Melatonin should be collected around midnight (up til 2am) – in darkness – and then again the next morning upon rising (6am-8am). The midnight salivary Melatonin reference range is 10-40pg/mL; ‘target’ is 30pg/mL. Morning reference range is 1-3pg/mL (Healthscope Functional Laboratories: 2010)*.
  2. 24hr Urinary Excretion for 6-sulfatoxy-melatonin.

About Cortisol:

Cortisol is the major glucocorticoid (steroid hormone) produced in the adrenal cortex of the adrenal glands. Cortisol is a key stress response hormone – essential for carbohydrate, protein and fat metabolism; anti-inflammatory tasks, blood glucose regulation, and appropriate immune system function. Cortisol is essential for Triiodothyronine (T3 thyroid hormone) ‘expression’ because it up-regulates nuclear T3 receptors within the cells.

Cortisol also has a modulating effect on the male hormone Testosterone (Moseley: 2016)

Cortisol production varies throughout the day in a predictable rhythm; termed diurnal rhythm. Output is highest in the early morning – falling to its lowest concentration at night as Melatonin rises. Persons suffering ‘Adrenal Fatigue’ (Cortisol insufficiency) exhibit a ‘flattened’ – or even inverted Cortisol profile where ‘morning surge’ is absent.

Due to its anti-inflammatory actions, Cortisol insufficiency should always be considered where ‘unequally localised’ inflammatory conditions such as acne, eczema or other skin rashes; ovarian cyst pain, colitis, swollen joints or asymmetrical ear infections persist. “Inflammatory condition present; think inadequate Cortisol production” (Rebic: 2010).

Symptoms of Cortisol insufficiency are:

  • Morning tiredness unrelieved by sleep – a ‘classic’ sign, often with an energy ‘crash’ in mid or late afternoon.
  • An energy surge mid-evening where you feel more energetic to attend to tasks, clear thinking & brighter mood. However you don’t feel ‘ready’ to sleep until midnight or early hours of the morning.
  • Mood disturbance ( as anxiety, feelings of continual ‘stress’, restlessness or depressed mood)
  • Feelings of lightheartedness when standing up; sluggish pupil-contraction when bright light ‘challenged’.
  • Seek out salty or sugary, refined foods as quick energy hits.
  • ‘Fat’ pads (puffiness to varying degrees of intensity) under your eyes
  • Persistent inflammatory break-outs on the skin or joints.
  • Younger women may experience quite marked PMS discomfort & mood disturbance.

Simple sugars, alcohol, processed white flour are some dietary issues that erode Cortisol levels. Elevated Insulin levels – as found in some metabolic conditions – suppress Cortisol due to the ‘antagonist’ effect of Insulin on Cortisol.

Pathology testing may be evaluated and/or cross-checked through bloods, 24hr Urine collection or Saliva Hormone assay.

Although Cortisol insufficiency is mostly a secondary issue related to disturbed nutritional levels impacting on thyroid-adrenal axis, taking an adrenal support supplement to help promote or balance Cortisol is often beneficial for the person’s feelings of general well-being. The brands most recommended by Dr. Van Zanden (UNSW)* are:

  1. Solgar* Rhodiola concentrate
  2. ‘Thorne’  Rhodiola (Adrenal) support

Currently both brands require online purchase & importation through New Zealand or other reputable overseas websites.

Rhodiola (Rhodiola rosea)is an excellent adrenal support; an adaptogen neither stimulates nor suppresses but balances (Cortisol) levels; raising up when levels low + settling/calming when levels are high.

Copyright Anthony Pearce 2011 (revised January 2017)

References for this article are within body of article or sources obtainable on request.

*Now called Australian Clinical Laboratories

**Dr. Philip Van Zanden (UNSW) is my long-term mentor in thyroid-adrenal & Vitamin D research.