Melatonin Biorhythm

210 – Melatonin Biorhythm Profile

This profile is clinically indicated for sleep disorders, mapping 24-hour output of melatonin, providing an accurate assessment of the melatonin biorhythm. This profile will assist in the development of clinical protocols: sleep and mood disorders; biorhythm disruptions; seasonal depression; thyroid disorders; and immune dysregulation.

  • Four melatonin measurements over 24 hours.
  • Salivary testing to measure active level of melatonin actually doing work in the body.
  • Melatonin cycle mapping to help with evaluation of sleep disorders; commonly as follow-up to BH #205.

When Should I Run This Test?

If other adrenal tests and their subsequent therapies – as well as removal of sources of chronic stress and lifestyle changes – have not helped the patient with sleep, run this tests to evaluate the cycle of melatonin levels thoughout a 24-hour period to look for abnormalities.

Related Info


Melatonin (N-acetyl-5-methoxytryptamine) is a naturally occurring hormone found in animals, plants, and microbes.  In humans, melatonin is produced primarily by the pineal gland, located in the center of the brain. Melatonin forms part of the system that regulates the sleep-wake cycle by chemically causing drowsiness and lowering the body temperature.  Production of melatonin by the pineal gland is inhibited by light and permitted by darkness.  Secretion of melatonin, as well as its level in the blood, peaks in the middle of the night and gradually falls during the second half of the night, with normal variations in timing according to an individual’s chronotype. (1,2)  Melatonin is also important for its ability to scavenge free radicals and to regulate the activity and expression of antioxidant and pro-oxidant enzymes. (3,4,5)

In human plasma 61-85% of melatonin is weakly bound to proteins, and there is a close relationship between circulating free and salivary melatonin levels. (6) Melatonin enters saliva from blood either by passive diffusion or active transport. (7)  Melatonin is measurable in saliva, and the acrophases of saliva and plasma melatonin rhythms are significantly correlated. (8,9)  Plasma and salivary melatonin concentrations increase when moving from a supine to a standing position, and decrease when these positions are reversed, due to changes in plasma volume. (10)  Inflammatory processes such as periodontitis trigger an increase in plasma melatonin, which then increases melatonin levels in the oral cavity, where it may increase antioxidant protection. (11)
© Salimetrics


  1. Claustrat, B., Brun, J., Chazot, G. (2005).  The basic physiology and pathophysiology of melatonin.  Sleep Med Rev, 9(1), 11-24.
  2. Cajochen, C., Kräuchi, K., Wirz-Justice, A. (2003).  Role of melatonin in the regulation of human circadian rhythms and sleep.  J Neuroendocrinol, 15(4), 432-37.
  3. Jou, M.-J., Peng, T.-I., Yu, P.-Z., et al. (2007).  Melatonin protects against common deletion of mitochondrial DNA-augmented mitochondrial oxidative stress and apoptosis.  J Pineal Res, 43(4), 389-403.
  4. Rodriguez, C., Mayo, J.C., Sainz, R.M., et al. (2003).  Regulation of antioxidant enzymes: A significant role for melatonin.  J Pineal Res, 36(1), 1-9.
  5. Gupta, Y.K., Gupta, M., Kohli, K. (2003).  Neuroprotective role of melatonin in oxidative stress vulnerable brain.  Indian J Physiol Pharmacol, 47(4), 373-86.
  6. Kennaway, D.J., Voultsios, A. (1998).  Circadian rhythm of free melatonin in human plasma.  J Clin Endocrinol Metab, 83(3), 1013-15.
  7. Gröschl, M., Köhler, H., Topf, H.G., et al. (2008).  Evaluation of saliva collection devices for the analysis of steroids, peptides and therapeutic drugs.  J Pharm Biomed Anal, 47(3), 478-86.
  8. Voultsios, A., Kennaway, D.J., Dawson, D. (1997).  Salivary melatonin as a circadian phase marker: Validation and comparison to plasma melatonin.  J Biol Rhythms, 12(5), 457-66.
  9. Vakkuri, O. (1985).  Diurnal rhythm of melatonin in human saliva.  Acta Physiol Scand, 124(3), 409-412.
  10. Deacon, S., Arendt, J. (1994).  Posture influences melatonin concentrations in plasma and saliva in humans.  Neurosci Lett, 167(1-2), 191-94.
  11. Cutando, A., Gómez-Moreno, G., Villalba, J., et al. (2003).  Relationship between salivary melatonin levels and periodontal status in diabetic patients.  J Pineal Res, 35(4), 239-44.