Melatonin Test: Guide to Types and Results

medica-seed-editor · November 3, 2026, 4:15am

A melatonin test measures the levels of the hormone responsible for regulating the body’s biological clock and sleep-wake cycle to diagnose sleep disorders.

What is a Melatonin Test?

This is a medical examination designed to determine the amount of melatonin secreted by the pineal gland in the brain. Production of this hormone increases in darkness and decreases upon exposure to light; therefore, levels peak at midnight and are lowest in the early morning. Beyond sleep, it helps regulate the menstrual cycle and protects the brain from certain neurodegenerative diseases, such as Alzheimer’s and Parkinson’s.

Types of Melatonin Test

There are several methods used to measure this hormone based on the sample collected:

Saliva Test: Multiple samples are collected over 24 hours, which is useful for diagnosing sleep phase disorders and determining when hormone secretion begins.
Blood Test: Samples are drawn from a vein at different times of the day.
Urine Melatonin Test: This does not measure the hormone directly but measures its metabolites, most notably “6-sulfatoxymelatonin.” This method is considered accurate because the metabolite remains stable in the bladder overnight, sparing the patient from frequent awakenings to collect samples.

Melatonin Test Preparation and Instructions

Procedures vary depending on the type of exam:

For saliva tests:

Fast from food and drink (except water) for one hour before the sample.
Avoid brushing teeth, using lip balm, or chewing gum one hour before the test.
Use only dim lighting when collecting nighttime samples.
Stop taking melatonin supplements 3 days before the test.
Inform the laboratory if you are taking medications such as antidepressants, anti-anxiety drugs, or cannabis products.

For blood tests:
Blood is drawn from a vein. An intravenous catheter may be inserted two hours before the draw to ensure that adrenaline does not affect the results.

For urine tests:
Four samples are collected: one immediately upon waking in the morning, another two hours later, one in the evening, and a final one before bed.

Melatonin Levels Meaning

Normal values vary by time. In saliva, nighttime levels (12 midnight) range between 15 and 40 pg/ml, and daytime levels (6 am) are less than 14 pg/ml. In blood, nighttime levels range between 18.5 and 180 pg/ml, and daytime levels between 2 and 80 pg/ml.

Causes of High Levels

Taking tryptophan supplements or overdosing on melatonin.
Seasonal affective disorder or anorexia nervosa.
Pituitary tumors or polycystic ovary syndrome.
Use of certain medications such as fluvoxamine and St. John’s Wort.

Causes of Low Levels

Aging, as natural hormone production decreases.
Exposure to bright artificial light at night or working shift patterns.
Stress, excessive caffeine, tobacco, or alcohol.
Taking medications such as beta-blockers, calcium channel blockers, or high doses of vitamin B12.

When Does a Doctor Order a Melatonin Test?

The test is requested when symptoms indicate a biological clock dysfunction, such as:

Difficulty falling asleep or frequent nighttime awakenings (fragmented sleep).
Excessive daytime sleepiness.
Waking up very early without feeling rested.
Sleep disorders related to traveling across different time zones (jet lag).

FAQ

What is a melatonin test?

It is a medical procedure used to measure the levels of the sleep hormone in the body to evaluate the circadian rhythm and diagnose sleep-related issues.

Can you get melatonin levels checked?

Yes, levels can be checked through clinical tests involving blood, saliva, or urine samples to determine if there is a deficiency or excess.

How to test melatonin levels at home?

Some tests allow for the collection of saliva or urine samples at home according to a specific schedule, which are then sent to a laboratory for analysis.

Does a melatonin sleep aid help in specific medical conditions?

Yes, it may be used to treat insomnia resulting from certain blood pressure medications (beta-blockers), or to treat jet lag and sleep cycle disorders.

When to Visit a Doctor?

It is recommended to consult a doctor immediately if you notice the following signs:

Chronic insomnia that prevents you from performing daily activities.
Severe mood changes or depressive episodes linked to sleep patterns.
Unexplained weight gain coinciding with sleep disorders.
Severe drowsiness that affects concentration and driving during the day.

Disclaimer: This content is for informational purposes only and does not substitute for professional medical advice.