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Millions of people take melatonin as a sleep aid, and some are left staring at the ceiling in shock about their bizarre or unpleasant dreams. If you recently took melatonin and had horrible dreams, you are not alone, and science may be able to explain what is happening in your brain.
Reports of vivid or bizarre dreams (often classified as nightmares) have been observed in both children and adults who take melatonin. Reports indicate nightmares were an adverse effect in a minority of melatonin users. The relationship between melatonin and nightmares is complex. Some people report having nightmares during melatonin use, but we do not know if melatonin itself is the culprit or if there are co-factors at play.
To understand to what extent melatonin may impact your dreaming, we must first investigate how melatonin operates in your brain. Endogenous melatonin is a naturally synthesized hormone that is primarily synthesized in the pineal gland, which regulates the body's circadian sleep-wake cycles via relationships with the suprachiasmatic nucleus of the hypothalamus and the retina.
Recent pioneering research has helped to reveal exactly how melatonin activates the phase of sleep, REM sleep, where most vivid dreams also occur. Scientists have identified the melatonin MT1 receptor as a crucial regulator of rapid eye movement (REM) sleep. Within the brain, the melatonin MT1 receptor interacts with the noradrenaline neurons in the locus coeruleus. During REM sleep, activity of noradrenaline neurons quiet down and stop firing.
Research indicates that individuals on melatonin showed noteworthy enhancements in percentage of REM sleep and various subjective measures of sleep quality. The alterations in REM sleep led to increased opportunities for more vivid dreaming—as well as potential nightmares.
A study published in 1987 found that during REM sleep, melatonin releases a substance known as vasotocin, which assists the brain in memory erasure while an individual dreams. Extra melatonin can increase the amount of vasotocin released into the brain—this translates into prolonged memory-erasing sleep, resulting in more vivid and lasting dreams.
We reached out to Dr. Michael Grandner, Sleep Expert and Professor of Neuroscience and Physiological Sciences, to hear about his thoughts on melatonin and dream intensity: "Melatonin can enhance the duration and intensity of REM sleep, which may lead to heightened levels of vivid dreams." The increase in REM activity can potentially explain why some individuals report more vivid and memorable dreams—including some nightmares—when incorporating melatonin supplementation.
A systematic review required an extensive search and included 37 randomized controlled trials where nightmares were reported as one of the adverse events associated with melatonin. Nightmares were classified as infrequent and were primarily mild-moderate in severity. The majority of adverse events either resolved spontaneously within a few days without an adjustment to melatonin, or immediately upon withdrawal of treatment.
In one documented case report, the patient was prescribed ramelteon (a melatonin receptor agonist) for insomnia. Shortly after initiation, the patient began experiencing vivid nightmares and ceased taking treatment soon thereafter. The patient reported improvement in the nightmares immediately after discontinuation of ramelteon. Emerging research suggests involvement of the melatonin pathway in the generation of nightmares.
In elderly adults, melatonin peak concentrations following oral doses can be much higher, even by as much as 240% compared to adults younger than 45 years. In addition to individual differences in the metabolism of melatonin (resulting in bioavailability variability), there is heightened risk for unpredictable serum concentrations that can also alter the response from melatonin. This may also help explain the variation in nightmare experiences for melatonin users.
In interviewing Dr. Suzanne Gorovoy, Sleep Expert, Clinical Psychologist, and Behavioral Sleep Medicine Specialist, about the variation in melatonin response from individual users, Dr. Gorovoy stated: "Personal factors like levels of stress, undiagnosed sleep disorders, and differences in brain chemistry determine how melatonin interacts with dream content." This individualized response pattern may be why some people have a higher susceptibility to nightmares over others.
When you are sleep deprived—not getting sufficient time in REM sleep—you will have longer-than-normal periods of REM sleep when allowed to achieve better sleep quality periods, known as the REM rebound effect. Longer periods of REM sleep following sleep loss often lead to vivid and colorful dreaming and are completely normal.
If you have been sleep deprived prior to starting melatonin, the sudden improvement in sleep quality may ultimately cause REM rebound, escalating dream intensity, including nightmares.
Melatonin, particularly at supraphysiological doses, may produce minor adverse reactions, including headaches, rashes, gastritis, nightmares, and insomnia. Higher doses of melatonin are associated with increasing the likelihood of minor adverse drug reactions, including dream disturbance.
Adults can initiate treatment with melatonin at 1 mg and increase by increments of 1 mg weekly if they find they are still having difficulty falling asleep. Beginning with the lowest dose that is effective may decrease the odds of having nightmares and still provide the sleep aid benefits.
A recent study done by researchers at McGill University is an important advancement on the role of melatonin in sleep and dreaming. Scientists initiated the use of an experimental drug that activates MT1 receptors to decrease the activity of noradrenaline neurons in rats and successfully increased REM sleep duration. This study is important because sleep-facilitating medications on the market primarily only contribute to the increased duration of non-REM sleep.
This study helps clarify why melatonin users report different dream content compared to other sleep aids. Nonetheless, in general, there are currently no medications targeting REM sleep specifically. Most hypnotic medications allow patients to get more sleep because they prolong total sleep duration, but do so at the expense of REM sleep, while melatonin enhances REM sleep and is therefore different than sleep aid medications.
While infrequent but vivid dreams or mild nightmares are not necessarily concerning, there are certain circumstances where a more alarming episode would warrant medical investigation:
We asked Dr. Areti Vassilopoulos, a sleep specialist, pediatric health psychologist, and assistant professor of child psychology, regarding when to seek assistance for nightmare issues. Dr. Vassilopoulos states: "When the frequency and intensity of nightmares has an impact on sleep quality or day-to-day functioning, it is important to initiate the evaluation process to determine if there are any underlying conditions." Being able to access professional expertise will help you receive appropriate treatment for the sleep disorders which may exacerbate the frequency of nightmares.
Dose-wise, experts recommend taking melatonin in the range of 1 to 3mg of melatonin each night. For most individuals, melatonin is relatively safe to take. However, excessive dosing can result in side effects, and reduction of doses is proposed to lessen the frequency of nightmares but continue to yield sleep benefits.
Another consideration is that taking melatonin late at night may carry through to the early morning hours when the sleep effect could extend throughout the night. Most experts recommend adults take melatonin anywhere from 1-3 hours before bed.
Melatonin in combination with appropriate sleep hygiene habits can improve sleep and lessen the likelihood of nightmares:
Melatonin can likely be used safely short-term, meaning one to two months, although there have been no studies to inform its long-term utilization. Those who've taken melatonin indicate that for most people, melatonin has significant benefits with few side effects when used short-term. Recently, a meta-analysis noted that melatonin was effective for reducing sleep latency, improving sleep quality, and increasing total sleep time in individuals taking it compared to those taking placebo. The possibility of nightmares, as real as it may be, likely only affects a small portion of the people taking melatonin.
If you have nightmares while taking melatonin, do not just assume you need to stop taking melatonin. Work with a healthcare provider to fine-tune your melatonin dosage, dosing timing, and/or sleep approach, as you may be able to find a good balance between melatonin and sleep without unwanted dream experiences.
Importantly, you should speak with a healthcare provider before starting or stopping a supplement regimen, particularly if you have underlying health problems or take other medications.
Dr. Shiyan Yeo
Dr. Shiyan Yeo is a medical doctor with over a decade of experience treating patients with chronic conditions. She graduated from the University of Manchester with a Bachelor of Medicine and Surgery (MBChB UK) and spent several years working at the National Health Service (NHS) in the United Kingdom, several Singapore government hospitals, and private functional medicine hospitals. Dr. Yeo specializes in root cause analysis, addressing hormonal, gut health, and lifestyle factors to treat chronic conditions. Drawing from her own experiences, she is dedicated to empowering others to optimize their health. She loves traveling, exploring nature, and spending quality time with family and friends.
