- Research has been reported showing that melatonin has a positive effect on sleep quality.
- The evidence score is 60, and reliability is moderate.
- The research targets adults, children, and people in specific medical situations, among others.
Melatonin is a substance examined in the context of sleep.
In research, it is treated as something taken as a supplement, and as a subject of examination in relation to sleep conditions.
There are reports that melatonin may have a positive effect on sleep condition.
This shows an improvement in sleep-related indicators compared with doing nothing (placebo).
Overall results show that sleep quality improved.
This kind of tendency is also shown by a meta-analysis (a method that combines and analyzes multiple research results) with as many as 1,683 participants. In other words, when a large amount of data is gathered and examined, the possibility emerges that melatonin is related to sleep.
Research on melatonin has been conducted in a variety of situations.
For example, a small-scale study with 203 adult participants hospitalized in the ICU (Intensive Care Unit: a room that manages the condition of hospitalized patients around the clock) found a result in which melatonin intake improved sleep quality. This study was carried out using the method of a randomized controlled trial (a highly reliable research method that randomly divides participants to compare effects). In other words, changes related to sleep quality have been reported even in specific medical settings.
Intake through food has also been examined.
In a study of a very small number of 20 healthy adults, it was shown that consuming cherry juice increased sleep duration and sleep efficiency, among other indicators. In other words, it is thought that components contained in specific foods may also affect sleep-related indicators.
It has also become clear that the effect of melatonin may differ depending on the circumstances.
For example, in research targeting 516 patients who underwent surgery, there is a report that melatonin did not produce a clear change in sleep quality. This study was also conducted as a meta-analysis (a method that combines and analyzes multiple research results). In other words, in specific situations such as after surgery, the expected result may not always occur.
Each study also has its own limitations.
Among the studies included in this data are some with a very small number of about 20 participants, and some that only conducted observation. Therefore, all of these results do not necessarily apply to everyone. 5 research reports on melatonin have been confirmed, but there are still parts that cannot be said to be certain.
| Study | Design | Number of Participants | Duration | Main Result |
|---|---|---|---|---|
| Unknown journal (2013) | Randomized controlled trial (RCT) | 125 people | 91 days | A positive effect was reported |
| PloS one (2013, PMID:23691095) | Meta-analysis | 1683 people | Unknown | A positive effect was reported |
| Critical Care Medicine (2020, PMID:33048904) | Randomized controlled trial (RCT) | 203 people | 7 days | A positive effect was reported |
| PloS one (2013, PMID:23691095) | Meta-analysis | 1683 people | Unknown | A positive effect was reported |
| European Journal of Nutrition (2012, PMID:22038497) | Randomized controlled trial (RCT) | 20 people | 7 days | A positive effect was reported |
| Journal of Clinical Pharmacology (2026, PMID:41014554) | Systematic review | Unknown | Unknown | A positive effect was reported |
| Canadian Journal of Anaesthesia = Journal Canadien d'Anesthesie (2023, PMID:36977935) | Meta-analysis | 516 people | Unknown | No clear association was found |
The research subjects include children with neurodevelopmental disorders (125 people), adults and children with primary sleep disorder (1,683 people), adult patients admitted to the ICU (203 people), healthy adults (20 people), and adult patients who underwent surgery (516 people).
The attributes of the subjects range widely, from people in a healthy state to patients admitted to the ICU and patients who underwent surgery, indicating that the result may differ depending on an individual's condition.
The study designs used include randomized controlled trials (RCTs), meta-analyses, and systematic reviews.
Some meta-analyses report that no effect was found on the sleep quality of adult patients who underwent surgery, compared with placebo.
It has also been reported that the number of subjects differs between studies, and that there is heterogeneity in review methods and the definition of outcomes.
Does melatonin affect the time to fall asleep?
Research has been reported showing a positive effect on the time to fall asleep. There are 2 such studies.
Does melatonin change sleep quality?
Research has been reported showing a positive effect on sleep quality. On the other hand, there is also a report from research targeting patients who underwent surgery in which no effect was found compared with placebo.
Is there melatonin research targeting children?
Yes, research targeting children has been reported. Specifically, this includes children with neurodevelopmental disorders and children with primary sleep disorder.
Multiple studies suggest that melatonin may have a positive effect on sleep quality. However, in some situations no effect occurs, and there is variation among the research results. Please note that this content is merely a report based on data from 5 studies.
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