Melatonin and Dosage By Weight and Age

5 min. read

Written by:



Did you know your body’s sleep-wake cycle is controlled by melatonin? It’s the body’s master sleep hormone produced in the pineal gland, found deep within the brain. It is the single most important factor in combatting the effects of sleep deprivation and getting good, restorative sleep. 

How Does Melatonin Work?

Melatonin production in the human pineal is controlled by light exposure. This was discovered in the early 1980s at the Massachusetts Institute of Technology (MIT).

Melatonin is naturally released from the pineal gland into your bloodstream on a cycle during the night when it’s dark—allowing you to sleep. But melatonin production is suppressed during daylight hours, so you stay awake. This production and suppression of melatonin is one of the circadian rhythms which constitute your body’s internal clock.

How Much Melatonin Do You Need?

Melatonin blood levels for a healthy young person are about 10 pg/ml during the day and 150 pg/ml at night.

At about 9:00 pm, melatonin starts to be released into your bloodstream so you become sleepy and fall asleep. When those levels are sustained during the night you remain in a deep, restful sleep. Then, as daybreak arrives melatonin production falls signaling you to wake up.

Many people over age 50 often can only produce enough melatonin to generate blood levels up to 30 pg/ml – 40 pg/ml at the peak of the sleep cycle, this causes them to wake prematurely, sometime between 1 a.m. and 4 a.m.

Other factors, besides normal aging, that can impede your body’s ability to produce sufficient amounts of melatonin include:

  • Medications, such as drugs for depression or blood pressure,
  • Energy drinks,
  • Coffee or other beverages containing caffeine,
  • Smoking.

Low Melatonin and the Effects of Sleep Deprivation

When your body doesn’t produce enough melatonin, it can lead to sleep interruptions and sleep deprivation. These can adversely impact health.

While feeling tired or cranky is the most obvious sign of sleep deprivation, it can also impact other aspects of health. In general, people who consistently sleep fewer than seven hours each night are more likely to experience additional health effects of sleep deprivation than those who sleep more than seven hours.

Research studies have also associated poor quality sleep with:

  • Poor cognitive function, especially short-term memory,
  • Changes in blood sugar levels,
  • High blood pressure,
  • Impaired immune function.

Sleep deprivation can also promote weight gain. A study of adults ages 67 to 96 found that those who slept less than five hours per night had a higher body mass index (BMI) than those who slept seven to eight hours. The “short sleepers” also had more central body fat and a higher total body fat percentage.

What Is the Right Melatonin Dosage for Adults?

Many people are confused about the right melatonin dosage for adults—and the right dosage is often far less than most people think.

In one study, people over age 50 were given three different single doses of melatonin: 0.1 mg, 0.3 mg, and 3 mg. The 0.3 mg dose resulted in the best outcome.

It successfully raised nighttime blood melatonin levels to those usually observed at night in young adults—allowing them to once again experience deep, restful sleep. Plus, it increased sleep efficiency. The greatest benefit was seen during the middle portion of the sleep; between 1 a.m. and 4 a.m. The higher test dose was less effective probably because it desensitized melatonin receptors in the brain. (Such doses, sometimes 5 mg or 10 mg, are sometimes taken in the erroneous belief that more is always better.)

The optimal dosage of 0.3 mg melatonin can help you fall asleep fast. However, it clears the body in about four hours. Then, you may need another boost of about 0.6 mg to stay asleep the rest of the night.

Taking melatonin in a single high dose can diminish its benefit by desensitizing the brain. What may help is taking melatonin in divided doses with a unique capsule-within-a-capsule design. The outer capsule has a fast-dissolving shell that releases 0.3 mg of liquid melatonin to help you fall asleep easily and stay asleep for about 4 hours. Then the inner capsule releases 0.6 mg of melatonin in slow-dissolving microbeads to help keep you in a sound sleep for the rest of the night.

How Much Melatonin Is Too Much?

When you take too much melatonin, it becomes less effective. Exposure to high doses of melatonin – 1 mg or greater for a week or two – can make the receptor proteins in the brain become progressively less responsive. The result is sleep problems become worse.

You can resolve the dilemma by switching to a low-dose melatonin preparation (0.3 or 0.6 mg) in a dual-dose or time release capsule. These amounts are much lower than those provided in most melatonin products. (People taking melatonin products that provide 3 or 5 or 10 mg are taking far too much.)

Research recommends 0.3 mg as the optimal dosage, much lower than what is available in most melatonin products, which means almost everyone using the supplement may be taking too much.

Mega-doses of melatonin cause two problems:

  • As stated above, you can become desensitized to melatonin. Special receptor proteins that interact with melatonin are bombarded with excess amounts of the hormone, becoming overwhelmed. That leads to them becoming increasingly desensitized to melatonin until they stop working altogether.
  • Blood levels of melatonin may remain elevated during the daytime, confusing your body’s natural 24-hour circadian rhythm. It can also lead to drowsiness during the day and the inability to fall asleep at night.

Remember that while melatonin establishes the rhythm and timing of your natural sleep/wake cycle, it doesn’t force you to go to sleep. People who take melatonin are likely to experience drowsiness but can stay awake if they choose to. It simply tells the brain that it’s time to sleep. When melatonin isn’t being produced in high enough levels naturally, sleep deprivation can occur.

Side Effects of Melatonin

Other than having melatonin becoming less effective at high doses, elevations in blood melatonin levels, melatonin during the daytime hours has been associated with grogginess, low body temperature, and a general “hung over” feeling. So, people who take very high doses shouldn’t operate machinery or drive.

Melatonin has no contraindications with drugs that have been prescribed by a doctor. Some melatonin is always present in the bloodstream so you can take it safely and without worry. It is not a drug or sleeping pill. When older people take it, it’s just restoring their nighttime blood melatonin levels to normal. However, consult your doctor to discuss any concerns you might have.

Healthy Directions Staff Editor