Does Melatonin Really Cause Nightmares? Myth vs. Science

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    Melatonin can be a powerful hormone that promotes deep, restful sleep. But does this deep sleep cause nightmares? We examine this common concern.

    Millions of people use melatonin supplements to support a night of restful sleep. It’s become one of the most common and popular supplements. Still, people worry that melatonin may give them nightmares. With the benefits melatonin offers, we’ll examine where this belief comes from and what you can do to get the best, most restorative sleep.

    What is melatonin?

    Most people are familiar with melatonin as a sleep support supplement. But melatonin is also naturally produced by the body. It is the only hormone made by the pineal gland, and it encourages drowsiness. Melatonin production is triggered by darkness and supports a healthy sleep and wake cycle. Daylight (or lights in the home) will decrease the body’s production of melatonin, signaling waking hours and keeping the body in a proper circadian rhythm. However, melatonin isn’t just the “sleepytime hormone.” It also has antioxidant benefits and can collect free radicals, preventing them from causing damage to cells.

    How melatonin affects sleep

    Melatonin is a hormone that the body produces to induce sleepiness and more uninterrupted sleep. It can also be taken as a supplement to promote deep sleep. When taken as a supplement, it usually takes between one to two hours for effects like drowsiness to start. Melatonin supplements can be especially helpful as a sleep aid for jet lag when traveling between time zones. Care/of’s Sleep Blend, for instance, relaxes the mind for better sleep and can help with falling asleep naturally.

    Melatonin and the sleep-wake cycle

    Melatonin is a neurohormone that is synthesized from the amino acid tryptophan and the neurotransmitter serotonin. Interestingly enough, tryptophan is one of the most abundant amino acids in turkey, which is why Thanksgiving turkey has a reputation for making you sleepy!

    As mentioned previously, the production of melatonin is necessary for regulating the sleep-wake cycle, also known as the circadian rhythm. By interacting with specific receptors in the brain, melatonin signals to the body that it’s time to prepare for sleep. It helps synchronize various physiological processes, including body temperature, hormone production, and alertness levels, to align with the natural sleep pattern.

    For those with an altered circadian rhythm, such as shift workers or individuals suffering from jet lag, melatonin supplementation can be beneficial by supporting healthy sleep.

    Melatonin and light exposure

    Light exposure is one of the key factors in the regulation of melatonin. When exposed to light later in the day, the natural production of melatonin can be suppressed. While any light source can have this effect, it’s believed that blue light emitted by electronic devices may have a more significant impact on melatonin levels. This is why it’s recommended to stay off your phone and turn off the television at least one hour before going to bed.

    Conversely, exposure to bright light earlier in the day supports a better circadian rhythm. It signals to the body that it’s daytime, promoting alertness and delaying the onset of melatonin until the evening.

    Does melatonin cause nightmares or vivid dreams?

    There are multiple phases of sleep, which combined are often referred to as “sleep architecture.” These phases include:

    • Non-REM Sleep (NREM): This type of sleep cycles through even more specific phases, from an initial light sleep when you first fall asleep to the deep sleep that is hard to be awakened from. Breathing and muscle movement slow during deep NREM. Brain waves also slow and the body uses this time to regenerate.
    • Rapid Eye Movement Sleep (REM): As the name implies, this is when brain activity increases, dreaming occurs, and heart rate and blood pressure rise. This phase occurs around two hours into a night’s sleep and usually lasts for approximately ten-minute spans. As we get older, REM sleep diminishes.

    Melatonin’s exact effect on sleep architecture has not been definitively determined by clinical research. In fact, no conclusive evidence has been published to show how dreams differ while using melatonin. However, because melatonin can encourage greater levels of REM sleep – the sleep phase when dreaming occurs – there may be a reason why melatonin has been linked to more vivid dreams.

    One study of a small group of college students taking 6mg of melatonin found that female college students had more occurrences of bizarre dreams involving fantastical images like object transformation. They did not describe bad dreams or nightmares, however.

    Why melatonin causes nightmares or vivid dreams

    If you notice you have more vivid dreams when taking melatonin, it may be because your body is experiencing more periods of deeper sleep. Melatonin may encourage your body to remain in REM sleep for longer periods. REM sleep is when we dream the most. So melatonin may support more REM sleep, an important component of a restful night’s sleep. But, it would be the REM sleep that actually brings about those vivid dreams. But it’s not just melatonin that may inspire vivid dreams. Stress, anxiety, emotional trauma, grief, and certain medications can all lead to nightmares or vivid dreams.

    What should you do if you're experiencing nightmares after melatonin supplementation?

    The first thing to do if you experience nightmares while taking melatonin is to decrease your nightly dosage. Begin with a small dose. Care/of’s Sleep Blend supplement, for instance, comes with 2.5 mg of melatonin in each capsule. This allows each user to tailor their dosage to their needs. Some people may want to take two capsules, while others may only want to take one. Care/of’s Sleep Blend also includes sleep-promoting herbs such as passionflower, ashwagandha, and valerian extract. As a result, you get to enjoy a more diverse sleep aid that doesn’t rely entirely on melatonin for sleep support. These herbs can also be used individually, if preferred.

    Tips to limit having melatonin cause vivid dreams

    Combining a smaller dose of melatonin with good sleep hygiene can further prevent vivid dreams. Sleep hygiene can help you fall asleep more quickly and help lead to a more relaxed brain and body. Some positive steps to take to support good sleep hygiene include:

    • Putting away all electronic devices at least one hour before bed.
    • Setting time aside before bed for relaxing, including enjoyable activities like reading or meditation.
    • Turning down lights beginning one to two hours before bedtime and following the cycle of the sun.
    • Maintaining a regular and consistent bedtime and morning wake-up schedule.
    • Taking in natural sunlight for at least 15 minutes each day.

    Understanding melatonin doses

    Melatonin dosages can vary widely depending on the product and individual needs. Research studies have utilized a range of doses, typically between 0.1-10 mg, given up to 2 hours before bedtime. Individual responses to melatonin can differ, so it's best to start with the lowest effective dose and adjust as necessary.

    Since melatonin is a supplement and not an actual medication, the FDA is not required to regulate the dosages. Some supplements have been found to contain far more or far less melatonin than indicated on the label. To ensure quality and accuracy, it’s a good idea to look for melatonin products that have undergone third-party testing.

    Other side effects of melatonin

    Melatonin is generally well-tolerated. Side effects, if any, are usually mild and can vary depending on the dosage and specific formulation, such as extended-release versions. The most common side effects include drowsiness, headaches, and mild anxiety.

    Caution should be used in individuals with certain health conditions, including those conditions that affect the immune system, since the interaction between melatonin and immune system cells is not fully understood by research. It’s always recommended to discuss any supplements, including melatonin, with your medical provider before starting them.


    Melatonin helps promote sleepiness, so it naturally can cause drowsiness. For this reason, it should only be taken when you are in safe surroundings to fall asleep. It should not be used when operating a vehicle or machinery.

    There is also a possibility for it to cause mild daytime sleepiness. It should not be mixed with alcohol or other medications or supplements designed to relax muscles, calm mood, or induce sleep. This can lead to an increased risk of side effects.


    Another possible side effect is headaches. However, these are usually mild and only occur with much higher intakes.

    Mild anxiety

    Some individuals have experienced mild anxiety when taking melatonin. But this side effect is generally mild and varies from person to person. In fact, research has noted that melatonin can have a soothing effect on certain types of tension. Studies have also suggested that melatonin may actually have a positive impact on fear and tension.

    The mild anxiety that users have reported could be due to the nightmares they may have experienced, but again, those are mostly associated with very high intakes. Everyone has individual responses to supplements, so it’s best to discuss side effects or concerns with your healthcare provider.

    How long do melatonin side effects usually last?

    When melatonin is taken at appropriate dosages, it will affect the brain in a similar way as the natural hormone. It can support healthy sleep onset, is not habit-forming, and does not typically cause next-day drowsiness.

    The duration of melatonin’s effects can vary depending on the formulation and dosage. The half-life of melatonin, which refers to the time it takes for the concentration of a substance to reduce by half in the body, is usually around 1-2 hours. This means that within 1-2 hours, half of the melatonin you consumed will be eliminated from your system. Typically, a substance is completely cleared from the body within 4-5 half-lives, indicating that melatonin is generally eliminated within 4-10 hours.

    The bioavailability of a supplement also influences its effectiveness in the body. Melatonin supplements are usually between 1-74% bioavailable. Overall, melatonin side effects are generally temporary and last for a relatively short period of time.

    When to seek a healthcare professional

    If you continuously experience sleep challenges, nightmares, or unsettled sleep, there may be other physiological issues to address. Talk to your doctor, who may recommend a sleep study to detect possible physical issues. If no physical causes are found, talking to a sleep psychologist can be helpful to learn cognitive therapy techniques for addressing issues that may be disrupting your sleep.

    The bottom line

    Melatonin is a hormone that is responsible for regulating the sleep-wake cycle and promoting restful sleep. While there is limited scientific evidence to suggest that melatonin directly causes nightmares, individual experiences may vary. Melatonin supplementation is generally considered safe and well-tolerated, but it's important to exercise caution and consult a healthcare provider if you have underlying health conditions or take medications. Prioritizing a comprehensive approach to sleep hygiene, incorporating melatonin if needed, can contribute to better sleep quality.

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    Dr. Carla Montrond Correia ND, CNS
    Medical Content Manager
    Dr. Montrond-Correia is a licensed naturopathic physician and a certified nutrition specialist (CNS). She holds degrees from University of Bridgeport, Georgetown University, and University of Saint Joseph, and supplemented her education with internships in the health and wellness space. She's focused on research, herbal medicine, nutrigenomics, and integrative and functional medicine. She makes time for exercise, artistic activities, and enjoying delicious food.
    Jordana Tobelem, RD
    Freelance Contributor
    Jordana Tobelem is a Registered Dietitian who enjoys helping others become the best versions of themselves through proper nutrition education. Jordana is passionate about promoting lifestyle changes through nutrition, physical activity, and behavior to create a superior quality of life. She uses her experience in the clinical field of dietetics to provide consulting services to an array of healthcare brands and companies. Jordana loves finding the most current research in nutrition to create meaningful content to share with her clients. Jordana has been a member of the Academy of Nutrition and Dietetics since 2018 and also holds certifications in both Personal Training and Health Coaching.