How Long Does Melatonin Last?

Trying to find out how long Melatonin lasts so you can take the correct amount and wake up feeling refreshed in the morning? There is no worse feeling than waking up late in the morning due to oversleeping because of your sleep aid!

Finding the right amount of Melatonin is key to waking up on time and avoid common side effects like grogginess and headaches.

How Long does Melatonin Last in your System?

Want to know how long Melatonin will last in your system after taking a pill before bed?

The answer will depend on a few factors like:

  • Amount of Melatonin
  • Body weight
  • Tolerance
  • Fluid intake
  • Your metabolism

The biggest factor will always be the amount of Melatonin you took, if it was quick release or time delayed, The more milligrams the longer it will be in your system. Melatonin has a short life of about 5 hours so it does not stay in your system long but be careful, a small dose goes a long way! Some studies have shown adults need as little as 150 micro-grams to fall asleep faster. Most people think that more is better and end up over dosing themselves.

Smaller doses have shown to be just as effective as large ones and cause less side effects in the morning! Instead of taking large doses of Melatonin try taking your normal dose, using a sleep mask and not drinking caffeine after dark!

Melatonin Effect Chart

Size by mg


.5 mg 1 hour
1 mg 2 hours
2 mg 3 hours
3 mg 4 hours
4 mg 5 hours
5 mg 6 hours
10 mg 7 hours

In the Bloodstream

Melatonin last even less time in the bloodstream, sometimes leaving the plasma in as little as an hour! Remember, there is little benefit to taking larger doses as you feel most of the effects in the first 30 minutes, not to mention the short half life. Instead of doubling up on your nightly dose, try finding other ways to get better sleep like exercising more or sleeping in a more comfortable bed!

How long to kick in?

Melatonin kicks in fast! Only take some if you are ready to go to bed, don’t try to “time” it! There are many factors that effect how long it takes for Melatonin to start working but you should start to feel something after 20 to 30 minutes.

Melatonin regulates the biological clock inside the pineal gland. This endocrine gland regulates and controls the sleep schedule – aka the circadian rhythm (as well as control reproductive hormones!).

How long does melatonin make you sleep?

Melatonin’s duration largely depends on the amount taken but is also impacted by other factors like your REM cycle and your natural need for sleep! Most people will sleep soundly all night with a normal dose before bed.

Best Times to take Melatonin

Not sure when is the best time to take you Melatonin? Like we talked about before the best time to take Melatonin (or any medication) depends on a variety of factors. The biggest factor outside of body chemistry is what kind of sleeping problems you experience. Science tells us it peaks in the blood stream after about 30 minutes but how should you know when to take it?

  • Insomniacs – The best time for insomniacs and other people having trouble sleeping (but not diagnosed with a sleeping disorder) is a half hour before laying down. It does not matter if you swallow a pill, let is dissolve on your tongue or chew a gummy – the effects are the same!
  • Kids – Due to their smaller bodies children are able to digest and process Melatonin faster than adults. In most cases you will start to see droopy eyes and hear snoring kids 15 to 20 minutes after taking some.
  • With a sleep disorder – If you have been diagnosed with a sleeping disorder you should not take Melatonin unless recommended by your doctor – especially if you are also taking other sleep medications.

Duration of Side Effects

Wake up in the morning feeling some of the common side effects of Melatonin like grogginess, headaches, body aches and cramping? Most of the side effects will pass in a few hours! If you want the effects to pass a quicker try drinking some water and eating breakfast. We recommend a hearty meal of eggs and bacon with a side of orange juice to start every day off right.

Related – Does Melatonin Cause Constipation?

Marie Seska

Marie Seska

Marie Seska is one of the most trusted sources on the net for sleep information. She searches the web - as well as the latest medical journals to bring her readers the latest news and information.

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