Side Effects Of Melatonin Supplement On The Heart And Depression

Melatonin is a naturally occurring compound, a hormone found in human beings and other mammals. It is produced by pineal gland situated in the brain. The main function of melatonin is to regulate sleep and wake cycle in human beings. Products containing melatonin are available as dietary supplements in United States; however in many other countries this neurohormone requires a prescription for its use.

Though melatonin is beneficial in many conditions, increase dosage or its use is known to produce melatonin side effects. Before knowing what are melatonin side effects it is necessary to know what its use is, and how these natural compound helps humans in their daily life.

Benefits Of Melatonin

Melatonin synthesis has cyclical pattern, it is produced more as the night approaches or during the dark phase of the day. The level drops abruptly as soon as the day approaches. Even a brief exposure to light at night rapidly suppresses melatonin production. The level of melatonin starts decreasing as a person ages.

People above the age of sixty have low melatonin level due to its low secretion in the pineal gland, and that is the reason they often have difficulty in sleeping. Melatonin is useful for people associated with shift works, persons traveling more often and complaining of jet leg, blind person, insomnia and aged individuals.

Melatonin Supplement Side Effects

If you are having sleeping problem or insomnia, you may be taking sleeping pills. These sleeping pills contain melatonin. Consuming excess of melatonin synthetic products may cause unwanted melatonin side effects.

Following are the reported side effects of melatonin: headache, nausea, depression, dizziness, sleepwalking, weight gain, heart problem, sleepiness during day time, and discomfort in abdomen.

Most of the side effects such as drowsiness and sleepiness occur when melatonin supplement is taken during the daytime.  Avoid driving or operating heavy machinery if you are taking melatonin supplement.

Melatonin side effects weight gain: studies have shown that deficiency of melatonin is correlated to weight gain, especially around the waist and abdominal area.

 When the level of melatonin is low in your body, you may have diminished sleep. Lack of sleep raises certain hormones in your body. Cortisol, leptin are these hormones. Rise in these hormones is known to cause weight gain. A person who sleeps for 5 hours in a day may be prone to increase in his weight than a person who properly sleeps for 7 to 8 hours.

Melatonin Side Effects On Depression And Heart

Melatonin side effects depression: If a patient is suffering from depression and he is already taking anti-depressive medicine, addition of melatonin supplementation may worsen the symptoms. Therefore a person suffering from depression should always consult his physician before taking melatonin supplementation.

Melatonin side effects on heart

A normal healthy individual has his heart rate between 80 to 100 beats per minute. If anything beyond this is considered as abnormal. Tachycardia is the medical word used for increased heart rate. One of the side effects of melatonin is tachycardia. The heart rate increases even when the body is resting when you take melatonin, as one of its side effect. Tachycardia will raise the blood pressure and put further load on your heart leading to condition such as heart attack of stroke. In case you feel palpitation and sudden increase in heart rate after taking melatonin supplement, you need to immediately consult your doctor.


  1. Heinz

    Do not use melatonin much. Last night I took a 5 mg slow release and previous to that also took one Tafitram pill and .07 5mg Pramipexol for restless legs. On getting up his morning I felt wobbly that stayed with me all day.

  2. Mark

    I started a new weight training program about a month ago, so I have been tracking my heart rate and BP (as well as weight and body fat %) on a weekly basis over the past month. It had positive effects on my BP, but I noticed that my resting heart rate has slowly increased from 67 to 82 bmp.
    I thought maybe it is because I was overtraining and then it dawned on me that I also started taking melatonin to help me sleep at night during that same period. I usually only take half of a 3 mg pill, but this week I upped the dose to 3mg, and my heart rate increased from 74 to 82 bmp over the last week. Thanks for the article, after reading this I am definitely going to stop taking it.
    I consider 82 bpm to be high, since I am used to having it in the 45-65 range (when I was doing cardio on a regular basis, which I am not doing now). I am confident that I am not over-training, so I’ll have to stop taking the melatonin and see if that has an effect.

  3. Shane

    I usually take a 12mg pill every night, but recently I ran out of them. I bought a different brand and the new ones are 5mg, so I took 2 tablets equaling 10mg. I woke up after 1am with sweaty hands and feet, and chest pains with a rapid heartbeat and a numb left arm. I was doing some research because I couldn’t sleep, and found that one of the side effects of melatonin is a rapid heartbeat. Not sure completely if it is the cause, and I will be going to the hospital to get a check up to make sure.

  4. Mary

    I also recently started taking melatonin 10 mg instead of 5 mg. Last night for the first time since I had laser ablation on heart, my heart started beating irregularly. I work up to a very fast heart beat, then suddenly it slowed down for a few seconds, then started racing again. This happened three times, one after another. Then it went back to a regular beat.

    The suddenness heart beat increasing was what I think woke me up. It did scare me a bit. Could it have been due to melatonin? Maybe I will reduce it to 3mg or just stop taking it. I am 65 years and much worried about heart attack or a stroke.

  5. Darryn

    I have been taking melatonin for about 8 months and sleeping so much better. I usually take 5mg tablet, but after running out of it, I found it at other place at a much better price. These tablets are 10mg each (timed release supposedly) and I figured 5 more mg per night wouldn’t hurt. But recently, I have been noticing increased heart rate and abnormal heart rhythm, especially when I sleep on my side. I thought it was due to my caffeine intake increasing, so I cut back on that, but the heart problems persisted. I never realized that melatonin could be the cause.

  6. Cayee

    I have noticed that many people here saying that they are taking 5 mg or above. This is not a healthy dosage and even people with insomnia are not usually prescribed more than 1 mg. Taking higher dosages won’t make it work better, in fact it may end up damaging your sleep cycle even more and also put you more at risk for side effects. I have 5 mg tablets but always cut them into 4 pieces and only have 1/4th a night which is still above what dosage you should take.

  7. Carol

    Thanks to those who shared the side affects from the melatonin. The last two nights of waking up with my heart racing, it felt like my heart was beating out of my chest. It scared me so much that I will not be taking it anymore. I have been taking this for the past few months and slept really good.

  8. Louis

    This is crazy. I was sitting at the airport two weeks ago, and it felt like my heart gave one huge beat. My head felt flush, and I felt like I would pass out. I went to the doctor and my heart was fine. I decided to wear a Fitbit to monitor my heart rate. Just now, two weeks later, my heart did it again. I casually brought it up to a work colleague, and she mentioned that melatonin caused that to happen with her a few years ago. I just started taking it about a month and a half ago, and I did not relate the two together until now. It is comforting to see others have experienced the same thing.

  9. Aaron

    Looks like I am experiencing something similar to you guys. I had been using a 3mg melatonin supplement that you dissolve into water and drink. As they were out of stock I bought a 5mg mouth dissolve tablet last night instead thinking that 2mg wasn’t much more. But I had really restless sleep after I took it last night. I noticed that my heartbeat was a bit faster than it usually is and I woke up sweaty. The 3mg supplement sort of did the same thing on one occasion but It was a lot less pronounced when it did happen.

    I have been dealing with some anxiety or stress related insomnia, and I have discussed it with my doctor and that he said it was okay to take it on a regular basis. The side effects happened maybe twice in a time span of about three weeks of semi-consistent use. Either I will try to find my old supplement, cut the tablets of the 5mg in half or try to ween off of it completely.

  10. Karina

    I am relieved to see quite a few others experiencing similar symptoms as myself. I have been taking a 3mg tablet every night before going to bed without too many issues. Although at times and with increasing regularity I have been waking up very sweaty. The most disconcerting symptom however, has been a racing heart, feeling like my heart was struggling to keep up.

    Last night was the worst (which has prompted me to check in with Google) I woke up about two – three hours after taking the Melatonin, with my heart beating very fast and the pressure gave me an instant and throbbing headache, which I still have into the next day. I shall be laying off the Melatonin for a few days to see if the symptoms resolve on their own. Thanks to all for sharing, much appreciated.

  11. Chris

    Thanks for sharing, this has confirmed it for me. I had been taking 2 gummies (5mg each) which is what the pack suggested to take and I had been doing fine, no problems but my dad accidentally purchased the 10mg gummies and the bottle said to take 2 so I did thinking what could it hurt. But today I have had a faster heart beat and palpitations. So I would say that there is a definite correlation here.

  12. Lisa

    Wow, this is quite a revelation. I have taken melatonin in the past but not on a regular basis. Recently I have been experiencing severe insomnia and and started taking melatonin every night. After waking with a rapid heartbeat in the middle of the night, I have taken another 3 mg but was never able to go back to sleep because of a very heavy heartbeat. Today l have been awake since 3am at which time I took a 3mg dose of melatonin. My heart is beating out of my chest. I will be calling the heart doctor asap and might even go to the hospital. After reading these posts I am convinced that melatonin is the problem and will never touch the stuff again. Thank you all.

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