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What is a circadian phase / melatonin levels test?

By now you’ve likely heard about melatonin and know that it has some relationship with sleep. You may have seen it on the shelves in the supplement aisle of your grocery store and wondered if this is the key to a restful night’s sleep. But what is it, why measure it, and can it restore your sleep-wake cycle by resetting your body’s internal clock? The answer, as you may have guessed by now, is often complicated and directly linked to your own body’s unique biology.

Salimetrics’ Circadian Phase Tests measure melatonin levels over time to determine if your sleep-wake cycle is functioning properly and in alignment with your environment and intended sleep cycle. At this time, melatonin assessments, specifically Dim Light Melatonin Onset (DLMO), are considered by sleep experts to be the most accurate and objective assessment of circadian timing. You can think about your circadian function as a finely tuned orchestra, where the “conductor” (your internal clock) meticulously coordinates the timing of each instrument’s note. Just like a symphony, if any instrument (e.g., melatonin production) plays out of sync or too loud, the harmony of your sleep-wake cycle is disrupted.

Unfortunately, the biological “conductor” that exists inside us all to signal proper sleep timing can lose their ability to hear over time. This is when things begin to drift out of alignment. Since our internal rhythm is no longer in sync, we are now left with symptoms that may indicate multiple different problems. Currently, the only way to truly understand how this intricate biological process is working in your body is to track melatonin levels over time, as rising melatonin is a primary biomarker of an individual’s sleep phase.

Why check melatonin levels?

The information you get from a melatonin assessment is both vast and valuable. Just from the timing of the samples themselves, you can look at your melatonin profile and get a visual insight into your daily biological routine. Your sleep-wake cycle could be delayed (you get tired too late), advanced (you get tired too early), or you could have an irregular sleep-wake cycle where your circadian rhythm shifts over time.

Your melatonin levels could also be too high or too low when they shouldn’t be, or even non-existent. Often people who take melatonin supplements or sleep aids don’t realize the biological impact over time. Melatonin supplements alone can shift the circadian rhythm further out of alignment or remain in the body long after you need to be awake and functioning again. Therefore, it is not recommended to start supplementing until you know approximately when your sleep onset occurs. This way you can properly time the administration of any treatment to match your sleep-wake cycle and prevent further dysregulation.

While melatonin may primarily function to properly prepare the body for sleep, that’s not the only function it provides. Melatonin also helps to regulate body temperature, cardiovascular function, immune function, and acts as a powerful antioxidant.  There’s also emerging evidence that low melatonin levels are also associated with stress and depression. Therefore, abnormally low melatonin levels can also signify other significant health concerns. You can read more about some possible future treatments using melatonin supplementation on WebMD, such as for reducing migraines, blood pressure, and even cancer. You can also read this article from Harvard Medical School on Sleep and Mental Health or this article from The Sleep Guru.

What is Melatonin and How Does it Impact Sleep?

Melatonin production is a natural process produced by many living creatures, and in humans, production is part of a complex system inside your body called the endocrine system. This is the system responsible for releasing hormones directly into your bloodstream. Melatonin production begins and ends with a pea-sized gland in the center of your brain called the “pineal gland”.

While there’s lots of information online that dives into the complexities of melatonin production, let’s try to simplify this. Here’s the gist of it: Basically, the amount of light that hits your eyes, sends signals that eventually reach the pineal gland and tell it to produce or restrict melatonin production. Bright light exposure sends a message to produce little to no melatonin and darkness sends a message to produce more melatonin in normal individuals. In nature, since light is dependent on the sun, which rises and sets on a 24-hour cycle, life itself is aligned to this cycle, which in turn, guides the circadian rhythm. The circadian rhythm is basically a 24-hour routine that happens inside our bodies every day.

Now here’s the good stuff; In human biology, since we are programmed to be awake during the daytime, melatonin production is low, and at nighttime, melatonin production increases to prepare us for sleep. While the full functionality of our hormonal influences is still being researched, one thing has remained constant: Melatonin’s primary function is to regulate your circadian rhythm and plays a primary role in your sleep-wake cycle.

Since melatonin is so closely connected to your circadian rhythm and sleep-wake cycle, you can determine if your circadian rhythm is functioning properly with a circadian phase test. Remember how your circadian rhythm cycles roughly every 24 hours? That means you can check your melatonin levels at specific times to see how much melatonin you have in your body. The key timing is generally around when you attempt to go to sleep, and when you wake up. Sampling over these times will reveal what the body is doing at this time.

However, one key element is to remain in dim light when you’re taking a melatonin test. As you now know, melatonin production begins when it’s dark, so if you are staring into bright lights in the evening, this will artificially lower your natural melatonin levels, and you won’t be able to tell if your rhythm is shifted naturally, or if it’s shifted due to light exposure. This is important because your daily routine has trained your melatonin production rhythm over time. This helps you function normally in your day-to-day life, even if the sun was to suddenly set, say an hour early. However, if the sun set an hour early every day, your circadian rhythm would eventually adjust to this schedule over time. This is why daylight savings time or jet lag can be so painful because for the first few days your body is adjusting to the sudden shift in light-dark timing. This is also what makes a melatonin assessment so valuable because it reveals shifts in your rhythm in the absence of light.

Testing Melatonin Levels in Saliva

You can measure melatonin in saliva, urine, and blood and each has its own pros and cons. Salimetrics tests measure melatonin in saliva so that it is easier for you to conduct a personal sleep study at home. Melatonin passively diffuses into your saliva through your blood and comparative results have shown that levels are highly correlated (meaning that if levels in blood increase, then the levels in saliva will also increase to the same degree). This is advantageous because you can easily provide a saliva sample, whereas blood sampling would require you to go to a lab and be punctured by a needle. However, there are few other reasons why saliva is so beneficial for melatonin assessments. Since you are looking at melatonin levels over time, collecting saliva is much easier than performing multiple blood draws or attempting to calculate total urine output over the same period of time. Remember, the whole point of a melatonin assessment is to capture the production of melatonin over time (a circadian phase) so that you can visually see irregularities in your circadian rhythm.

Melatonin Testing CliffsNotes