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Researchers commonly measure melatonin levels to:

• Establish an individual’s circadian rhythm and explore related disorders
• Identify shifts that disrupt normal biological functions and physiological disorders
• Determine an individual’s dim light melatonin onset (DLMO) time point
• Explore disruptions in the sleep-wake cycle

Establishing a Melatonin Profile

Nicknamed the “darkness hormone,” melatonin levels are high at night and low during the day.  It is well-established that exposure to light during darkness greatly inhibits melatonin production.  The transition from day to evening initiates its production, an event called Dim Light Melatonin Onset (DLMO).  Establishing a melatonin profile can help determine an individual’s DLMO time point, which is important in therapeutic applications.

6-sulfatoxymelatonin (aMT6s) as a Surrogate Biomarker

Melatonin has a half-life in humans of just 10 to 60 minutes, and more than 90% of circulating melatonin is deactivated by the liver.  Through a series of processes, melatonin is converted into 6-sulfatoxymelatonin (aMT6s) which is excreted and can be measured in urine as a surrogate biomarker.  Urinary aMT6s levels closely mimic the melatonin profile of the general population, and first morning urine samples can be used to evaluate the melatonin rhythm of the prior night.  Measuring 6-sulfatoxymelatonin in urine provides a non-invasive, integrated parameter to assess circadian rhythms over a period of time.

Available Sleep Disorder-Related Immunoassays and Products

NovoLytiX offers the most sensitive immunoassays for the measurement of melatonin and its key metabolite in urine, 6-sulfatyoxymelatonin, including products formerly offered by BÜHLMANN Laboratories. ALPCO is now the exclusive distributor of NovoLytiX products in North America. Products for sleep medicine research include:  

Item	Catalog #	Sample Type
6-Sulfatoxymelatonin ELISA	12-EK-M6S-U	Urine
Direct Saliva Melatonin RIA	12-RK-DSM2-U	Saliva
Direct Saliva Melatonin ELISA	12-EK-DSM-U	Saliva
Melatonin RIA*	12-RK-MEL2-U	Serum, Plasma, Urine
Melatonin ELISA	12-MLTN-96-U	Saliva
NEW! Serum/Plasma Melatonin ELISA (includes extraction columns)	12-MLTN-PL-U	Serum, Plasma, Urine, Other fluids.
Caffeine ELISA	12-CAFN-96-U	Other Fluids, Food, Plasma, Saliva, Serum
Cortisol Urinary ELISA	20-CORHU-E01-URN	Urine
Cortisol ELISA (Saliva)	11-CORHU-E01-SLV	Saliva
NEW! Cortisol (Saliva) ELISA (sensitive)	11-CRLHU-E01-SLV	Saliva
Cortisol ELISA	11-CRLHU-E01	Serum
Cortisol RIA	38-CORHU-R96	Plasma, Saliva, Serum, Urine
Creatinine ELISA	74-CRNHU-E02	Urine
Vasopressin RIA	12-RK-VPD-U	EDTA Plasma, Urine
Vasopressin RIA*	12-RK-AR1-U	EDTA Plasma, Urine
Vasopressin ELISA (AVP/ADH)	74-VSPHU-E01.1	Cell Culture, Plasma, Serum
Item	Catalog #	Description
Salivette Collection Devices	12-B-SVC50-U	For simple, hygienic collection and storage of saliva samples. Each box contains 50 units.
Saliva Collection Device (for Cortisol and Melatonin)	12-B-SCDC50-U	For simple, hygienic collection and storage of saliva samples for measurement of cortisol and melatonin. Each box contains 50 units.
Melatonin Extraction Columns	12-B-MECX	For use with 12-RK-MEL2-U and 12-MLTN-PL-U. C18 silica extraction columns available in boxes of 10x10 units for extraction from biological samples.
Angiotensin/Vasopressin Extraction Columns	12-B-AECX	For use with Vasopressin RIA (12-RK-AR1-U). Solid phase extraction containing 500 mg C18 silica in boxes of 100 units for extraction from biological samples.

*Extraction recommended. See associated extraction devices.
References

• Keijzer H. et al. (2014): Why the dim light melatonin onset (DLMO) should be measured before treatment of patients with circadian rhythm sleep disorders. Sleep Med Rev. Aug;18(4):333-9.doi:10.1016/j.smrv.2013.12.001
•  Zawilska et al. (2009): Physiology and pharmacology of melatonin in relation to biological rhythms, Pharmacol Rep. May-Jun 61(3):383-410.  doi: 10.1016/s1734-1140(09)70081-7.
• Basket et al. (1998): Sulphatoxymelatonin excretion in older people: relationship to plasma melatonin and renal function. J Pineal Res.;24(1):58–61. doi:10.1111/j.1600-079X.1998.tb00366.x.
• Graham C et al. (1998). Prediction of nocturnal plasma melatonin from morning urinary measures. J Pineal Res. 24(4):230–8. doi:10.1111/j.1600-079X.1998.tb00538.x.
• Pandi-Perumal SR et al. (2007) Dim light melatonin onset (DLMO): A tool for the analysis of circadian phase in human sleep and chronobiological disorders. Progr Neuropsychopharmacol Biol Psychiatry 31, 1-11. doi: 10.1016/j.pnpbp.2006.06.020.
• Benloucif S et al. (2008): Measuring Melatonin in Humans. J Clin Sleep Med. 4, 66-9. PMCID: PMC2276833
• Nagtegaal JE et al. (1998) Delayed sleep phase syndrome: A placebo-controlled cross-over study on the effects of melatonin administered five hours before the individual dim light melatonin onset. J Sleep Res 7, 135-43. DOI: 1046/j.1365-2869.1998.00102.x
• Lewy AJ et al. (1999) The endogenous melatonin profile as a marker for circadian phase position. J Biol Rhythms 14, 227-36. DOI: 1177/074873099129000641
• Scheer FA et al. (2005): Melatonin, sleep, and circadian rhythms. Sleep Med Rev 9, 5-9. DOI: 1016/j.smrv.2004.11.004
• CKlerman EB et al. (2005): Clinical aspects of human circadian rhythms. J Biol Rhythms 20, 375-85. DOI: 1177/0748730405278353
• Nagtegaal JE, Smits MG et al. (2001): The effect of melatonin administration on sleep, daytime sleepiness and performance after a period of night work. In: Pharmaceutical, chronobiological and clinical aspects of melatonin. Veenendaal: Universal, 93-111
• Sack RL. Clinical practice. Jet Lag. N Engl J Med 362, 440-7 (2010)
• Van der Haijden KB et al. Prediction of melatonin efficacy by pretreatment dim light melatonin onset in children with idiopathic chronic sleep onset insomnia. J Sleep Res 14, 187-94 (2005)
• Heukelom RO, Prins JB et al. Influence of melatonin on fatigue severity in patients with chronic fatigue syndrome and late melatonin secretion. Eur J Neurol 13, 55-60 (2006)