The production of melatonin is inhibited by daylight and occurs during darkness. Thus, melatonin levels are very low during day and rise in the evening. Melatonin is a conservative Molecule and as such is ubiquitous. Not only has it been described in humans and animals, but also in plants and even in microorganisms.

In humans circadian melatonin profiles in body fluids (saliva, serum, plasma) provides an excellent marker for the setting of the endogenous clock. Night-time levels peak at around 3:00 am (acrophase) in most healthy individuals. As a general modulator of human and other vertebrate biorhythm, melatonin is involved in the timing of functions such as sleep, mood, reproduction and immune system activities.

Both, the intra-individual Melatonin onset and acrophase are very stable. Therefore, it will be sufficient to measure the onset of melatonin production, only, once a whole melatonin profile has been established. The onset of melatonin production may be defined as the DLMO (Dim Light Melatonin Onset) for monitoring shifts of the profile.

BÜHLMANN offers most sensitive Immunoassays to measure any kind of biological sample by ELISA technique. An accurate ELISA to determine the main metabolite in urine, 6-sulfatoxy-melatonin, is also available.

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