How Melatonin + Serotonin Work Together

Melatonin and serotonin are two of the most common sleep-related household names. Below, we’re breaking down exactly how these two are different while answering common questions about how they also work together, like:

• How do levels of melatonin affect levels of serotonin?
• What role does serotonin play in melatonin synthesis?
• How can I naturally boost my serotonin and melatonin levels?

Melatonin is a hormone produced by the pineal gland in the human brain, then released into the bloodstream. Quantities naturally increase as the sun goes down and decrease during daytime hours and exposure to bright light, thus regulating the sleep-wake cycle (aka circadian rhythm).

When it’s produced within our bodies, it goes by the name endogenous melatonin; however, some also choose to supplement their natural levels as a way to effectively adjust and regulate their body's internal clock if they have trouble sleeping. In this form, it’s called exogenous melatonin.

There is research supporting the efficacy and safety of melatonin. One meta-analysis, (1) which compared melatonin against placebo in improving sleep parameters for patients with primary sleep disorders, showed that the supplement reduced sleep latency (the amount of time it takes to fall asleep) by 7.06 minutes and increased total sleep time by 8.25 minutes. Also promising was the fact that trials with a longer duration and higher doses of melatonin demonstrated greater effects on decreasing sleep latency and increasing total sleep time.

Melatonin is best for those suffering from circadian rhythm sleep disorders such as:

• Jet lag
  Officially known as "Rapid Time Zone Change Syndrome," jet lag messes with your sleep times and wake times as you cross into new time zones, especially when traveling east. Melatonin, when studied in vitro, has been found (2) to exhibit antioxidant properties that help ease jet lag.
  
  
• Shift Work Disorder
  Shift workers with inconsistent schedules have been found to get upwards of four fewer hours of sleep than the average person due to disrupted melatonin production. (3)
  
  
• Delayed Sleep Phase Disorder (DSPS)
  Night owls who fall asleep late but have a hard time getting up in the morning (common with teens and young adults).
  
  
• Advanced Sleep Phase Disorder
  Early birds whose body clock causes them to fall asleep and wake up on the early side (common with older adults).
  
  
• Irregular Sleep-Wake Rhythm Disorder
  When someone's sleep patterns are flipped upside down due to one-too-many naps over a 24-hour period.
  

READ MORE: Guide To Circadian Rhythms

Melatonin is commonly consumed between 1 (low dose) and 5mg by healthy adults. (4)

A small percentage of melatonin users have been found to experience next-day drowsiness/grogginess, sleepiness, headaches, and dizziness; however, there is no evidence of a risk for serious, clinically significant adverse events (AEs). (5) As a precautionary measure, it’s recommended that users not drive or use machinery for four to five hours after taking melatonin in the case of impairment.

Before beginning any new dietary supplement regime to target sleep problems, it's best to consult your healthcare provider for medical advice.

Yes. If you have low levels of melatonin, there are several lifestyle changes you can make to improve your sleep hygiene/sleep habits which, in turn, can help boost natural melatonin levels and help you get a good night’s sleep. Small, doable behavioral changes include relaxation techniques to calm a racing mind, cultivating an evening bedtime routine, steering clear of blue light/bright light exposure, and avoiding certain foods/types of physical activity at night to avoid raising your body temperature.

For those looking for personalized guidance, support, and accountability from an expert trained in behavioral patterns and strategies for change, we recommend sleep coaching.

It's important to do your research to ensure your supplement of choice contains what it says it does and is not contaminated with heavy metals or pesticides. Here's what to look for when selecting a supplement for short-term or longer-term use:

• Third-party tested for purity and verified free of heavy metals, microbes, and pesticides
• U.S. manufactured and produced in a Food & Drug Administration (FDA)-approved, "Good Manufacturing Practices"-compliant facility
• If the supplement has other active ingredients or botanicals, ensure they are standardized to guarantee consistent purity, potency, and efficacy
• Free of artificial colors or binders
• Non-GMO and, if it’s important to you, vegan, gluten/dairy/sugar-free

READ MORE: The FDA Regulates Supplement Facts Differently Than Nutrition Facts. Here’s Why.

Although serotonin is commonly referred to as the “happy hormone” that helps stabilize our mood, it's not actually a hormone. Rather, it's a neurotransmitter that carries messages between nerve cells in our brains (aka the central nervous system) to the rest of our bodies (aka the peripheral nervous systems). It acts as a regulator that plays a role in everything from memory to mood, body temperature to libido, anxiety to digestion. But for our purposes, we’re just going to talk about its impact on sleep, which is impactful because serotonin plays an important role in the production of melatonin with a little help from a chemical compound called n-acetylserotonin.

Here’s where things get a bit complicated. Certain studies (6) have found that TOO much serotonin promotes wakefulness and may inhibit REM sleep. (7) That said, there’s overwhelming evidence that serotonin is necessary for our pineal gland to produce melatonin, (8) a hormone that regulates our biological clock, also known as the circadian rhythm.

Although you can’t take serotonin supplements in the same way you’d take melatonin supplements, there are ways to naturally boost your levels. 

• Exercise
  Studies indicate that exercise may directly increase the serotonin function in the hippocampus and frontal cortex. (9-10) Additionally, evidence suggests that exercise also stimulates the production of tryptophan, which is a precursor to serotonin. (11)
  
  READ MORE: What’s The Best Time To Exercise For Quality Sleep?
  
  
• Bright light
  There are seasonal variations in our serotonin levels, which tend to be lower in winter and higher in the summer. (12) This has led researchers to believe that bright light and exposure to sunshine facilitates the skin’s ability to synthesize serotonin.
  
  
• Diet
  There are a handful of foods that are high in tryptophan, an amino acid essential for serotonin production. The most common foods include nuts, seeds, lean meat, dairy products, (13) bananas, eggs, (14) and barley grass powder. (15)
  
  READ MORE: The 15 Best + Worst Foods For Your Sleep
  
  
• Probiotic supplements
  Researchers have found (16) that probiotic supplements, which add more good bacteria to your microbiome (aka your gut) also help increase the concentration of tryptophan.

Depending on your individual circumstances, your healthcare provider may also recommend the temporary use of an SSRI, which stands for selective serotonin reuptake inhibitors. This is a type of antidepressant medication that prevents the brain from reabsorbing the serotonin it releases, thus leaving it more readily available. Your healthcare provider, if recommending this course of action, will also talk to you about the risks of serotonin syndrome.

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