Melatonin is a key biomarker for measuring circadian rhythm. In healthy individuals, production of melatonin follows predictable cycles and is suppressed by exposure to daylight. In the evening, melatonin production in the body is expected to rise about 2 hours before the onset of sleep. This is called Dim Light Melatonin Onset (DLMO).
Knowing the timing of a patient’s nocturnal melatonin secretion reliably evaluates the sleep-wake cycle to determine alignment or misalignment (phase delay or phase advance) from a typical 24-hour entrained circadian clock. Temporal shifts on the phase response curve can indicate abnormal sleep-wake patterns and provide clinicians with important data for sleep disturbance assessment.
Measuring the Circadian Clock
The most reliable measure of the timing of the central circadian clock in humans is the onset of the evening melatonin production measured in dim light, i.e., dim light melatonin onset, DLMO. DLMO is believed to accurately represent the timing of the central circadian clock (suprachiasmatic nucleus, SCN), as the secretion of melatonin from the pineal gland is controlled by the SCN. Typically, melatonin levels begin to increase in the 2–3 hours before the usual onset of nocturnal sleep, peak in the early morning hours, and decrease to daytime levels around usual waking.
The most noticeable feature of circadian rhythms is the sleep/wake cycle. But there are other circadian rhythms including swings in many hormones throughout the day, the body temperature cycle, appetite and the times of best alertness. Ideally these rhythms are in sync with each other and with the light-dark cycle in nature. Most humans are awake during daylight hours and sleep during darkness – it’s the ideal scenario for overall health. DLMO is a convenient phase marker to measure, as it can be obtained non-invasively from saliva, and can require only a relatively short window of sampling of 6–8 hours. For all of these reasons, the use of DLMO to assess circadian phase is proving to be a valuable tool for both researchers and clinicians alike.
BioHealth’s #220 DLMO Profile – Saliva Melatonin
* Eight (8) measurements of salivary melatonin for determination of DLMO phase.
* An effective alternative to inconvenient collections performed in clinics or labs.
* Performed using the Salimetrics melatonin assay, the industry standard – with higher specificity and consistency between tests, and a lower variability between replicate tests.
At-Home Testing DLMO
While commonly performed by patients in sleep clinics for many years, the at-home option for patients to perform DLMO saliva collections at home is a reality now for clinicians assessing circadian rhythm disorders. Patients are required to restrict certain foods and activities on the day of collection. The start time of the 8 hourly saliva collections starts 5 hours previous to the typical time of falling asleep. Restriction of light to > 30 lux is critical to a successful collection procedure, given that excess light will suppress melatonin. The patient stays awake for the entire DLMO collection process, freezes the samples, then ships them to the lab in a thermal container. Device apps like multi-timers and light meters can be downloaded to ensure compliance.
√ Lab Test
√ Doctor’s Written Review of Test Results
√ Doctor’s Recommended Course of Action
This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure or prevent any disease. Always consult with your professional health care provider if you are taking any medication.
NOTE: This test is not available to residents of New York or Maryland. Any orders originating from the state of New York, Rhode Island or Maryland will automatically be canceled. Any samples originating from the state of New York or Maryland will be discarded.