Melatonin Side Effects, Long-Term Dangers and Safe Usage

Melatonin side effects are generally mild when this supplement is used appropriate. Melatonin is a natural hormone, produced in the body to regulate sleep patterns. It is also used to alleviate sleep disorders, jet lag, mood disorders and to promote anti-aging benefits.

As a dietary supplement, it is rated as Likely Safe by the Natural Medicines Database. In research studies, it has been used safely for up to 6 months – 2 years in adults.

Melatonin is also rated as Possibly Safe for children, but it is not recommended to give it for long periods of time due to a higher risk of negative effects on gonadal development. It should also not be given to pregnant or lactating women without first consulting with a doctor.

What are the effects and side effects of melatonin supplements and how should you use this sleep aid to prevent adverse reactions? Furthermore, what interactions are possible if combining melatonin with other supplements or drugs?

Melatonin

Sleep Supplement

Sleep

Calmness

Daytime Alertness

How It Works:

• Reduces insomnia, jet lag & daytime fatigue
• Promotes restful sleep & calm mood
• Supports brain function, wellbeing & anti-aging

Dosage:

Between 0.5 - 5 mg per day

Safety:

Rated Likely Safe

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Melatonin Function in the Brain

The main function of the hormone melatonin is to regulate our circadian rhythm, or the human/mammalian sleep-wake cycle. When your brain receives information from your retina that it is dark, the pineal gland releases melatonin to prepare the brain and body for sleep.

Alternately, retinal information “telling” the brain that it is daytime significantly reduces the amount of melatonin released by the pineal gland.

External stimuli such as exposure to bright light at night, third shift and jet lag can disrupt the normal cycle of melatonin release/suppression and cause sleep disturbances.

Melatonin regulation and aging seem to be linked as well. Studies have shown that children present the highest nighttime melatonin levels.

Alternately, elderly people have lower nighttime levels of melatonin. This may explain why older people complain of sleep problems when no apparent physical or mental issue can be attributed to insomnia or waking too early in the morning. [1]

Effect of Melatonin Supplements

Melatonin supplements induce sleepiness by shifting the chronobiotic process of the sleep-wake cycle and promoting the onset of sleep by triggering the “homeostatic drive to sleep”. [2]

However, taking melatonin supplements in the morning appears to interrupt the normal phases of the circadian rhythm and often inhibits nighttime sleepiness even when the person is exposed to darkness for an extended period.

Consequently, doctors recommend taking melatonin only in the evening about two hours before going to bed. Dosages of between 0.3 to 5 mg per day have been used to improve sleep quality.

Melatonin Side Effects

Melatonin is available as a dietary supplement for help with relieving insomnia, nighttime waking, jet lag and other sleep disturbances. When taken in suggested dosages, adults report few melatonin side effects that include but are not limited to: [3]

• Morning grogginess/daytime drowsiness
• Decreased body temperature
• Vivid dreams and/or nightmares
• Minor fluctuations in blood pressure
• Headache
• Light-headedness

These minor side effects generally resolve themselves after seven to 14 days of taking a melatonin supplement. If morning grogginess, headache and dizziness continue, the amount of melatonin being taken should be reduced until side effects disappear.

Although no long term side effects of melatonin use have been reported in peer-reviewed journal articles, one study found that men who took melatonin for six months exhibited “decreased semen quality”.

This side effect was attributed by researchers to “inhibition of aromatase at the testicular level”. [13]. However, more studies are needed to affirm the validity of this particular study.

Melatonin Interactions and Adverse Effects

Certain prescription medications and herbal supplements may interact unfavorably with melatonin supplements. Always discuss taking melatonin with your physician if you are taking any kind of medication regularly, whether it is prescribed or an over-the-counter medicine.

Melatonin and Antidepressant: Melatonin combined with antidepressants such as Paxil, Prozac or Lexapro may reduce the ability of the antidepressant to relieve anxiety and depression. [4] I

In addition, some antidepressants, specifically selective serotonin reuptake inhibitors (SSRIs), may suppress release of melatonin from the pineal gland.

Counteracting this effect by taking melatonin supplements may relieve insomnia to a degree, but you should check with your doctor to find out if this is appropriate for you.

Birth Control Pills and Melatonin: Birth control pills contain powerful hormones such as levonorgestrel and ethinyl estradiol that may impact other hormones such as melatonin. Researchers are not sure why, but birth control pills prompt the pineal gland into making and releasing more melatonin than necessary.

Too much blood melatonin can disrupt the sleep-wake cycle and may cause other side effects specific to an individual’s physiology. [5]

Blood Pressure Medications and Melatonin: Mixing melatonin supplements with blood pressure medications (Clonidine, Vasoxyl) [6] can make them less effective at moderating hypertension.

However, a study involving subjects with untreated hypertension found that daily nighttime intake of melatonin significantly reduced high blood pressure at night. [7]

Anticoagulants and Melatonin: Melatonin could increase bleeding potential in people taking anticoagulant medications used for blood thinning and blood clot prevention.

Although aspirin is not considered an anticoagulant medication, [8] it is a blood thinner and should be taken with caution in combination with melatonin.

Immunosuppressant/Steroid Medications and Melatonin: Melatonin may render immunosuppressant medications ineffective. Do not take corticosteroids with melatonin unless under the supervision of a physician. [9]

Diabetic Medications and Melatonin: Melatonin may cause blood sugar levels to spike or rapidly drop. Diabetics interested in taking melatonin supplements will need to have their glucose closely monitored by their doctor so that medication adjustments can be implemented on an as-needed basis. [10]

Melatonin Side Effects on Dreams

Melatonin not only promotes sleep by increasing pineal gland activity but also facilitates our ability to reach the REM stage of sleep. This is the last stage of sleep that researchers believe involves memory organization and storage, learning, dreaming and even mood regulation.

During REM sleep, the brain sends signals to the spinal cord that suppresses movement (sleep paralysis) so that the majority of metabolic energy existing during sleep is used to regenerate the body and mind. [12]

Melatonin’s side effect on dreams varies greatly among melatonin supplement users, with some experiencing no change in dream activity and others reporting vivid dreams and nightmares.

Melatonin Side Effects for Children

A recent meta-analysis published in the International Journal of Pediatrics found that multiple clinical trials involving the use of melatonin on children with sleep disorders resulted in positive results. [13]

Melatonin not only exerts beneficial effects on a variety of dyssomnias but also on sleep disturbances experienced by children with ADHD, autism and autism spectrum disorders.

In addition, melatonin has been used successfully for sedating children undergoing anesthetic or surgical procedures and for subduing occurrences of epileptic seizures. According to this 2011 meta-analysis, side effects of melatonin supplementation in children have not been reported.

However, there is a concern that long-term use in children could cause changes in sexual development. Melatonin secretion in children has been shown to be inversely correlated to gonadal development.

This means that some researchers believe that melatonin could affect gonadal development in adolescents. More research is needed to understand this potential risk of negative melatonin side effects.

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