Melatoninthe sleep hormonenaturally signals to our bodies that its time for rest. The hormones levels are highest at night as it gets darker, and lowest in the morning when the sun rises. One in three Americans say insomnia negatively impacts their day-to-day lives, leading many to routinely take melatonin supplements in the form of capsules, gummies, or liquids with the hopes of hitting the hay faster. 

Although not essential for sleep, You definitely sleep better when your brain secretes melatonin appropriately, Dr. Raj Dasgupta, a pulmonary, critical care and sleep medicine specialist at the University of Southern California tells Fortune

But what are melatonin supplements actually doing to our bodies and brains?

We push up our body block 

Melatonin is naturally released from the pineal gland, located in the middle of the brain and helps regulate the circadian rhythm, or the bodys internal clock. When adults take a melatonin supplement, potentially to combat jet lag or a night shift, it can signal to the body that its time for rest at a new time.

What youre doing is trying to give your body that hormone, thats naturally released anyways, at a different time to help you shift your circadian rhythm, Dasgupta says. 

Melatonin may help adults fall asleep faster, and therefore, increase duration of sleep and potentially sleep quality, or ability to fall into REM or deep sleep.  

We may be taking too much

The FDA classifies melatonin as a dietary supplement for adults so there arent specific regulations on how much to take or for how long. Sleep scientists generally recommend between one and five milligrams for adults, yet not all brands of melatonin sold over-the-counter have clear dosage markers and some may even be higher than what the label says. Taking too much melatonin can cause headaches, vomiting, and even changes in blood pressure.

We may have side effects

The hormone naturally occurs in our body, which is why there are few warnings on the side effects of the supplement, Dasgupta says. 

Still, people may feel daytime sleepiness, headache, dizziness, and upset stomach, he says, noting that if the symptoms persist or are more than mild to see a health care provider. 

Short term melatonin use in adults is generally harmless, but theres limited guidance when it comes to long term use. After one to two months of routine use, experts recommend weaning off of it to see how you fare without the supplement and whether you need further sleep interventions, Dasgupta says.

We can become psychologically dependent

Experts recommend cognitive behavioral therapy and a healthy wind down routine (limiting screens before bed, and being in dark, cool spaces) for treating insomnia. Melatonin alone is not a very potent sleep aid, for adults Dasgupta says, leading some to speculate that any positive results from melatonin are a placebo effect. 

So if we perceive that the melatonin supplement aids our sleep quality, we can become enticed to keep taking itbecoming psychologically dependent on it. Unlike an addiction, this mental draw to melatonin doesnt cause the same harm that other drugs might, because the supplement doesnt cause the euphoria or pleasure associated with substances [known for] getting high, Dr. Lewis S. Nelson, director of the division of Medical Toxicology and Addiction Medicine at Rutgers New Jersey Medical School previously told Fortune. However, someone who is psychologically dependent on it may feel anxious if they cant access it.

We may assume melatonin causes our nightmares 

Some also associate melatonin with increased nightmares or dreaming, especially closer to the morning. Melatonin may increase the duration of sleep, and therefore indirectly increase the amount of time you spend in REM, or deep sleep, which is when we have dreams and nightmares, Dasgupta says.

By having more vivid dreams, it might make you feel like melatonin is the direct cause of those dreams, he says. 

Sleep duration and quality is imperative, and melatonin use in the short term may help adults in what Dasgupta deems a time limited trial, alongside other sleep regiments.

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