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Circadian DLMO Test Information Guide

Is Your Circadian Phase (DLMO) Normal, Delayed or Advanced?

Why do doctors recommend circadian rhythm testing and what can your circadian phase tell them? How does this test provide value in understanding your internal sleep clock? Here, we’ve put together some basic information to help you understand the importance of your circadian rhythm and how it affects your ability to both fall asleep and stay asleep. You can review the informational brochure below to better understand the who, what, where, when, why, and how circadian phase testing can paint an important picture of your body’s response to sleep.

Who is This Test For?

Do you go to sleep when your body goes to sleep? Many of us work against our body’s natural sleep timing. However, this simple circadian phase test can reveal your body’s natural sleep routine using saliva samples collected over the course of an evening.

Your sleep routine is also called your circadian clock or circadian rhythm, which tells your body when to go to sleep and when to wake up. A healthy circadian rhythm depends on the production timing and amount of melatonin in your body around bedtime. Melatonin is a natural hormone that helps regulate your normal sleep routine in a 24-hour light/dark, sleep-wake cycle. We can reveal this biological process through a circadian phase assessment called Dim Light Melatonin Onset, or DLMO, which begins when you are exposed to dim light in the evening every day.

With this test, a health professional can identify disruptions in your circadian rhythm and help you get your natural sleep cycle back on track.

What Does This Test Measure?

This test measures dim light melatonin levels from saliva samples in relation to your bedtime. After sunset, melatonin levels in your body should increase to prepare you for sleep. In many cases, prolonged exposure to bright light, dysregulation, or other events can shift your natural sleep routine, which may cause the rise in melatonin levels to occur too late, too early, or not rise much at all.

The Biology of Sleep

Below is an example of a normal and healthy circadian phase assessment that was designed to capture DLMO. The numbers on the graph below highlight areas of importance in relation to this individual’s circadian phase.


1 – Baseline
A normal baseline should be low, indicating that your body is not producing too much melatonin during the day when you need to be awake.

2 – Melatonin Onset
A normal melatonin onset will start to rise within two hours of your bedtime. This is when your body begins to prepare itself for sleep. This point is determined using your bedtime and baseline levels.

3 – Bedtime
A normal profile will show melatonin levels that continue to rise until bedtime. This is when you should feel tired and ready for bed.

4 – Peak
In a healthy profile, melatonin levels will either continue to rise or may flatten after bedtime. This indicates that your body is producing enough melatonin to maintain sleep. Sometimes levels will peak at bedtime too. This is generally normal unless there is a sharp decline post-bedtime.

Why Drs. Recommend DLMO?

With DLMO, a health professional can identify if there is a disruption in your circadian rhythm and help you get your natural sleep cycle back on track. A DLMO profile generally captures your overall circadian phase around bedtime. This indicates if you are working with or against your body’s natural circadian rhythm, such as if your DLMO is too early (advanced) or too late (delayed). The image below illustrates an example of melatonin levels over an entire night’s sleep under three different sleep phases.

Each phase above can assist your healthcare provider in guiding specific treatment(s) as well as dictating the amount and timing of your treatment(s). Knowing your circadian phase can be an invaluable resource in helping you achieve a better night’s sleep.

Frequently Asked Questions?

How do I get started?
Easy. Get a collection kit from your practitioner or order online.

What is in the collection kit?
This kit contains everything you need to collect, freeze, and safely return saliva samples to the Salimetrics’ CLIA-Certified Laboratory. This includes all instructions, forms, pre-paid shipping labels, and laboratory analysis. Once you order a kit, there are no additional fees to obtain your results.

What do I need to do?
With your collection kit, you will take a total of 7 or 9 scheduled saliva samples over time, freeze them, and drop off your return samples at the nearest FedEx drop-off.

Is it painful?
Not at all! You will be collecting saliva by drooling into a tube. Most people can easily perform the sample collection process. The only painful part is often staying awake for an hour past bedtime.

How do I receive results?
Results will be delivered via a HIPAA compliant e-mail portal within 7-14 business days from when the lab receives your samples.

Can I just take melatonin supplements?
It is best to consult with your healthcare provider. However, finding the right timing and amount of melatonin supplementation may require multiple rounds of estimation without knowing the effect it’s having on your body. This could also shift your circadian phase further out of sync, creating even greater disruption.

Contact: Salimetrics (USA)
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