It appears that your browser may be outdated and performance may be limited. The My Study builder is best viewed with the latest internet browsers. However, if you’d prefer to use our standard form, you can access it below.

Go to Internet Explorer Quick Quote Form

Dismiss this message

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 uncover your body’s natural sleep cycle using saliva collected over the course of one evening.

Your sleep cycle, also known as your circadian clock or circadian rhythm, prepares your body for when it’s time to go to sleep and when it’s time to wake up. Melatonin production timing and the amount of melatonin in your body around bedtime is one way to determine if your circadian rhythm is functioning properly. Melatonin is a natural hormone that helps regulate your normal sleep routine within a 24-hour light/dark, sleep-wake cycle. We can monitor this biological process through a circadian phase assessment called Dim Light Melatonin Onset, or DLMO, which begins in the evening when you are exposed to dim light 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 for sleep. In many cases, genetic factors, prolonged exposure to bright light, dysregulation, environmental effects, or even poor sleep hygiene can all 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. Many intrinsic circadian rhythm disorders stem from genetic factors, and are not easily reset through simple behavioral adjustments.

The Biology of Sleep

Below is an example of a normal and healthy circadian phase assessment that properly depicts DLMO. The numbers on the graph below highlight areas of importance in relation to an 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 around two hours before your normal bedtime. This is when your body begins to prepare itself for sleep. The onset is determined using your bedtime and baseline levels.

3 – Bedtime
A normal profile will show increasing 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. This is generally normal unless there is a sharp decline post- bedtime.

Why Drs. Recommend DLMO?

With DLMO, a health professional can more quickly and confidently identify if there is a disruption in your circadian rhythm and help you get your natural sleep cycle back on track. Your circadian phase around bedtime is also useful to determine if you are working with or against your body’s natural circadian rhythm, such as if your DLMO is too early (advance) or too late (delayed). The image below illustrates an example of melatonin production over an entire night’s sleep cycle under these different sleep phases.

Each phase above can assist your healthcare provider in guiding specific treatment(s) as well as appropriate amount and timing of your treatment plan. 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?
Simply order a collection kit from your sleep healthcare provider, or you can order online.

What is in the collection kit?
The 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 to 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 your normal 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)
View All International Distributors