Does Melatonin Actually Work for Chronic Insomnia? A Look at the Science
Quick Summary
Ineffective for Adults with Primary Insomnia: The review found that for adults whose insomnia occurs on its own (non-comorbid or primary insomnia), melatonin was not significantly more effective than a placebo at helping them fall asleep faster, sleep longer, or improve their sleep efficiency (Choi et al., 2022).
A Different Story for Comorbid Insomnia in Adults: In a single study of adults whose insomnia occurred alongside other medical illnesses (comorbid insomnia), melatonin did appear to significantly reduce the time it took to fall asleep. However, this is based on very limited evidence (Andrade et al., 2001).
Significant Benefit for Children and Adolescents: In contrast to adults, melatonin was effective for children and adolescents with chronic insomnia. The effect was particularly strong in children whose insomnia was comorbid with conditions like ADHD or autism spectrum disorder (Choi et al., 2022).
No Clear Impact on Sleep Quality: The analysis of studies that measured subjective sleep quality using various scales found no significant overall improvement for adults taking melatonin (Choi et al., 2022).
Melatonin and Sleep
Melatonin is one of the most popular over-the-counter sleep aids on the market. Millions of people reach for it, hoping for a natural solution to their sleep troubles, a problem that affects between 10% and 30% of the population worldwide. It’s often perceived as a gentle, safe alternative to prescription hypnotics. But despite its widespread use and reputation, what does the latest comprehensive scientific evidence say about its effectiveness for treating long-term, or chronic insomnia?
To find a definitive answer, a team of researchers conducted a major systematic review and meta-analysis, a rigorous scientific method where all high-quality studies on a topic are gathered and their results are statistically combined for a more powerful conclusion.
They synthesized the results from 24 different clinical trials to see if melatonin truly works (Choi et al., 2022). This article will break down what they discovered.
But first, what exactly is melatonin?
What is Melatonin?
Melatonin is a natural hormone (neurohormone to be more specific) your brain’s pineal gland produces in response to darkness. Its primary job is to regulate your body's internal 24-hour clock, known as your circadian rhythm. The nightly rise in melatonin acts as a signal to your body that it's time to reduce activity. Melatonin achieves this by helping to lower body temperature and decrease alertness, assisting the body in preparing for sleep.
Because melatonin levels rise in the evening, it's often called the "hormone of darkness" (Claustrat et al., 2005).
Why is Melatonin Thought to Help Sleep?
The theory behind using melatonin as a sleep aid is straightforward. Since the body's natural melatonin production helps to initiate the process of falling asleep, it's thought that taking an external (exogenous) dose can supplement the body's own supply.
This could be particularly helpful for individuals whose natural melatonin cycle is weak, delayed, or disrupted, thereby helping to shorten the time it takes to fall asleep and regulate the sleep-wake cycle. Because of this, it has become a first-line consideration for many people looking for a non-prescription sleep solution.
How Did The Researchers Investigate Melatonin’s Effect on Sleep?
The researchers analyzed 24 randomized controlled trials—the gold standard of medical research—that compared melatonin to a placebo in patients with chronic insomnia. This is defined as long-term difficulty with falling asleep, staying asleep, or experiencing poor sleep quality that leads to daytime impairment (Choi et al., 2022).
They looked at two main types of insomnia:
Non-comorbid Insomnia: This is insomnia that occurs on its own, without being attributed to another medical or psychiatric condition. It was previously known as "primary insomnia."
Comorbid Insomnia: This is insomnia that occurs alongside another condition, such as attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder, or other medical illnesses.
The review examined several key outcomes: sleep onset latency (the time it takes to fall asleep), total sleep time, sleep efficiency (the percentage of time in bed spent asleep), and subjective sleep quality.
The Verdict for Adults with Primary Insomnia
For adults whose insomnia was not linked to another health condition, the findings of Choi et al’s (2022) meta-analysis were clear and consistent: melatonin offered no significant benefits.
Does Melatonin Help Adults With Primary Insomnia Fall Asleep Faster?
No. When the results from 12 studies on this group were combined, melatonin did not significantly reduce sleep onset latency (time to fall asleep) compared to a placebo (Choi et al., 2022).
While some individual studies showed very small effects, the overall statistical picture from the meta-analysis was not significant. The average reduction in time to fall asleep was just 2.25 minutes, a difference so small it was not considered statistically meaningful and definitely not clinically meaningful (Choi et al., 2022).
Even when looking specifically at studies on adults aged 55 and older, like those by Wade et al. (2007, 2011) and Luthringer et al. (2009), the trend remained the same: no significant improvement.
Does Melatonin Help Adults With Primary Insomnia Sleep for Longer?
No. The analysis of 11 studies found that melatonin did not significantly increase total sleep time in this group compared to a placebo (Choi et al., 2022). The average increase in sleep time for adults taking melatonin was a negligible 1.23 minutes (Choi et al., 2022).
Furthermore, the review found no significant improvement in sleep efficiency. In the eight studies that measured this outcome, the difference between melatonin and placebo was not statistically significant (Choi et al., 2022).
Does Melatonin Improve an Adult's Perception of Their Sleep Quality?
This is a more complicated question because different studies used different tools to measure subjective sleep quality. The two most common were the Pittsburgh Sleep Quality Index (PSQI) and the Leeds Sleep Evaluation Questionnaire (LSEQ). When the researchers analyzed the results separately for each tool, they found no significant benefit.
For the studies using the LSEQ, there was no overall improvement in sleep quality scores (Lemoine et al., 2007; Luthringer et al., 2009; Wade et al., 2007).
Similarly, for the studies using the PSQI, melatonin did not lead to a statistically significant improvement in sleep quality scores compared to placebo (Wade et al., 2011; Xu et al., 2020).
The high degree of variation (heterogeneity) in the results across these studies also made it difficult to draw a firm conclusion, suggesting that the perceived effect of melatonin on sleep quality is inconsistent at best.
Does Melatonin Help For Insomnia Caused by Other Health Conditions (Comorbid Insomnia)?
This is where the story becomes more nuanced, and the answer depends heavily on the patient's age. The distinction between primary (insomnia alone) and comorbid insomnia (insomnia co-occurring with another physical or mental health condition) is critical, as the underlying reasons for sleep difficulties can be very different.
A Glimmer of Hope for Adults with Comorbid Insomnia
In a surprising contrast to the findings on primary insomnia, the review identified one study that looked at medically ill adults with comorbid insomnia. In this single study, melatonin did have a significant effect, reducing the time it took to fall asleep by an average of 42 minutes (Andrade et al., 2001). This is a clinically meaningful improvement and stands in stark opposition to the results for primary insomnia.
However, the review authors issue a strong caution: this promising finding is based on only one small study. Before any firm conclusions can be drawn, this result needs to be replicated in larger, more robust trials. It does, however, open an important door for future research, suggesting that melatonin might be effective when insomnia is a secondary symptom of another illness, even if it's not effective as a primary treatment.
A Clearer Benefit for Children and Adolescents
The evidence for melatonin's effectiveness was much stronger in children and adolescents, particularly those with comorbid conditions.
The review found that for children with non-comorbid insomnia, melatonin:
reduced the time to fall asleep by about 22 minutes; and
increased total sleep time by 27 minutes (Choi et al., 2022).
The results were even more pronounced in children with comorbid insomnia.
A combined analysis of several studies found that in children with conditions like ADHD, autism spectrum disorder, or Angelman syndrome, melatonin:
reduced sleep onset latency (time to fall asleep) by an average of 29 minutes.
Increased total sleep time by an average of 54 minutes.
These significant findings came from studies by Braam et al. (2008), which looked at children with Angelman syndrome; Cortesi et al. (2012), which studied children with autism spectrum disorders; and van der Heijden et al. (2007), which focused on children with ADHD.
This suggests that for pediatric populations where sleep difficulties often accompany neurodevelopmental disorders, melatonin can be a genuinely effective intervention.
What Were the Limitations of This Research?
The authors of the systematic review pointed out several limitations that are important for context:
Lack of Safety Data: This review focused only on efficacy (whether it works) and did not collect data on safety or adverse events. The long-term safety of melatonin use, especially in children, requires further investigation. This is particularly important given that melatonin can influence other hormonal systems.
Limited Studies in Younger Adults: Most of the adult studies focused on individuals aged 55 or older, as this is the population for which prolonged-release melatonin is often approved in some countries. There is a lack of high-quality research on the effects of melatonin in adults under 55.
Few Studies in Children: Although the results for children were positive, the number of studies was small. More research is needed to confirm these findings and to establish optimal dosing and long-term safety profiles.
Funding Bias: Several of the included studies were funded by pharmaceutical companies, which can introduce a potential for bias in the results. It is crucial for future research to be conducted by independent bodies to ensure impartiality.
Practical Takeaways
The main takeaway is that melatonin's reputation as a universal sleep aid is not supported by the current body of high-quality evidence. Its effectiveness appears to depend heavily on a person's age and the nature of their insomnia.
Here are the key points to consider:
For adults struggling with primary insomnia (insomnia not caused by another condition), melatonin is unlikely to provide a significant benefit over a placebo.
For adults whose insomnia is linked to another medical condition, melatonin might be helpful, but the evidence is very limited and you should speak to a doctor.
Melatonin may be a genuinely useful tool for children and adolescents with chronic sleep onset insomnia, especially those with comorbid neurodevelopmental conditions. However, this should always be discussed with a doctor before use.
The fact that melatonin is available over-the-counter does not mean it is a universally effective or appropriate treatment for all ages and all types of insomnia.
Clinical Comment
The scientific consensus, based on this large and comprehensive review, is that melatonin is not an effective treatment for most adults with chronic primary insomnia, a finding that challenges its popular use and perception pushed by social media.
We see the same in the clinic: melatonin doesn’t do anything for our clients with chronic insomnia.
This is not surprising given that melatonin’s role as a hormone is not to induce sleep but to signal to the body that it is nighttime. It simply isn’t a sleep aid. This is why melatonin is not recommended for chronic insomnia by the American Academy of Sleep Medicine.
The potential effectiveness of melatonin appears to be largely concentrated in children and adolescents. This seems to be a relatively consistent finding across other studies as well.
The study raised the possibly that melatonin may help in adults where insomnia is a symptom of another medical illness. We would think that this would only be in some specific situations, such as neurodevelopmental conditions where there can be circadian rhythm disruptions, typically delayed sleep phase disorder. We would further add that melatonin is considered a treatment option for circadian rhythm disorders, and can be helpful where medications that impact melatonin production are being used (e.g. some blood pressure medications, some anti-depressants etc). So once more studies in this area come out, they may help determine more closely what is going on here.
We suggest adults struggling with chronic insomnia, both primary insomnia and co-occurring insomnia, should explore other evidence-based treatments, such as the recommended first-line treatment for insomnia, Cognitive Behavioral Therapy for Insomnia (CBT-I), rather than relying on an intervention that has little scientific support for their age group and condition.
Frequently Asked Questions - Melatonin and Insomnia
Q1: What is the difference between primary and comorbid insomnia?
A1: Primary (or non-comorbid) insomnia is difficulty sleeping that occurs on its own, without being caused by another health problem. Comorbid insomnia is a sleep problem that occurs alongside another medical or psychiatric condition, such as ADHD, autism, or other chronic illnesses. The research shows this distinction is very important for melatonin's effectiveness.
Q2: Does melatonin work for adults with chronic insomnia?
A2: For adults with primary insomnia, the evidence says no. The comprehensive review by (Choi et al., 2022) found it was not significantly better than a placebo for helping adults fall asleep faster or sleep longer. For adults with comorbid insomnia, there is a small amount of evidence that it might be helpful, but much more research is needed (Andrade et al., 2001).
Q3: Does melatonin work for children and adolescents?
A3: Yes, the evidence is much stronger for this group. Melatonin was found to be significantly effective at helping children and adolescents fall asleep faster and sleep longer. The effect was especially pronounced in children who had comorbid conditions like ADHD or autism spectrum disorder (Choi et al., 2022).
Q4: Will melatonin improve my sleep quality?
A4: For adults, probably not. The studies that looked at subjective sleep quality using different rating scales found no significant overall improvement in adults taking melatonin compared to a placebo (Choi et al., 2022).
Q5: Is melatonin safe to take for insomnia?
A5: The systematic review by Choi et al. (2022) did not evaluate safety, which is a major limitation. The long-term safety of melatonin, especially for children, is not well established. Because melatonin is a hormone, there are concerns it could affect other bodily systems, so it's crucial to speak with a doctor before starting it, particularly for long-term use or for children.
Q6: If melatonin doesn't work for my insomnia, what should I do?
A6: If you are an adult with chronic insomnia, the most effective, evidence-based treatment is Cognitive Behavioral Therapy for Insomnia (CBT-I). This is a structured program that treats both physical sleep system disruptions that lead to sleeplessness, and helps you identify and manage thoughts and behaviors that are causing or worsening your sleep problems. It is recommended as the first-line treatment for chronic insomnia by sleep medicine associations worldwide.
References
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Written By The Better Sleep Clinic
Reviewed By Dan Ford, Sleep Psychologist
