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Article

Lippia citrodora (Lemon Verbena) Extract Helps Reduce Stress and Improve Sleep Quality in Adolescents in a Double-Blind Randomized Intervention Study

by
Pau Navarro
1,
Adrián García
1,
Roberta Villa
2,
Vincenzo Nobile
2,
Ortensia Ilaria Parisi
3,
Chiara Lirangi
4,
Fabio Amone
5,
Erminia D’Ambrosio
5,
Nuria Caturla
1 and
Jonathan Jones
1,*
1
Monteloeder SL, C/Miguel Servet 16, 03203 Elche, Alicante, Spain
2
R&D Department, Complife Italia S.r.l., 20024 Garbagnate Milanese, Milan, Italy
3
Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, 87036 Rende, Cosenza, Italy
4
Private Clinical Practice, Via Fratelli Salerno, 87036 Rende, Cosenza, Italy
5
Clinical Trial Department, Nutratech S.r.l., 87036 Rende, Cosenza, Italy
*
Author to whom correspondence should be addressed.
Appl. Sci. 2025, 15(11), 5856; https://doi.org/10.3390/app15115856
Submission received: 25 April 2025 / Revised: 16 May 2025 / Accepted: 20 May 2025 / Published: 23 May 2025
(This article belongs to the Section Applied Biosciences and Bioengineering)
Browse Figure
Versions Notes

Abstract

:
Adequate sleep is important for learning and memory in children and adolescents. Sleep disorder prevalence is high in adolescents, as well as stress, and both can affect their mental and physical health. To this end, the objective of this study is to evaluate the effectiveness of an herb extract, specifically lemon verbena (Lippia citrodora), in reducing stress and improving sleep quality in healthy adolescents. This study lasted 3 months, during which they filled out the Adolescent Sleep Wake Scale (ASWS) and Perceived Stress Scale for Children (PSS-C) questionnaires, and saliva samples were taken to analyze cortisol levels. Also, a psychologist evaluated the results of this study for each subject and concluded if they considered the treatment to be clinically relevant. As a result, significant improvements versus placebo were detected in the ASWS and PSS-C, starting in the first month of treatment, coinciding with a significant reduction in cortisol levels. The psychologist assessment agreed that the treatment was successful for 86% of the experimental group, compared to only 19% of the placebo group. In conclusion, the results of this study revealed that the product may help reduce stress and improve sleep quality in adolescents with sleep and stress issues.

1. Introduction

Sleep is an essential element for our health and wellbeing, necessary for both mental and physical recovery [1]. Benefits of good quality sleep include improvements in cognitive performance, physiological processes, mood, physical recovery and overall quality of life. In children, several studies have shown that sleep helps with memory encoding, working memory and long-term memory consolidation, as well as with other functions such as promoting physical growth and immunity [2,3]. In this respect, insufficient or poor quality of sleep can affect their academic performance, especially their executive functions, memory, and attention [4,5]. The prevalence of sleep issues in adolescents is high, being up to 60% in certain Western countries, and even higher in Asia. As this can have long lasting effects that can continue into adulthood, it is important to find solutions to help improve their sleep.
Both sleep and stress are strongly correlated, each affecting the other in a vicious loop [6,7]. This has been exacerbated during the COVID-19 pandemic, which negatively impacted the mental and physical health of individuals, particularly adolescents, and has a lasting effect still today [8]. Psychological interventions and even medication may be the go-to treatment for the more severe cases, but for non-pathological situations, a natural alternative is a more adequate approach. This includes adopting proper sleep hygiene strategies and behavioral therapy [9]. In some cases, melatonin may be used, though this should be prescribed and controlled by a health physician.
Besides adopting new strategies, there are also natural products that may help reduce stress and improve sleep quality [10,11]. However, there is little evidence on their efficacy in children and adolescents, with only a few case examples [12,13,14], and generally they are studied in non-healthy populations such as autism spectrum disorder (ASD), schizophrenia, bipolar disorder, or attention-deficit/hyperactivity disorder (ADHD).
Therefore, the objective of this study is to assess the efficacy of an herb extract in a healthy adolescent population with sleep and stress issues in a non-pathological setting. Lemon verbena was selected for this study, due to its demonstrated effectiveness in healthy adults [15,16]. This herb extract is highly purified in verbascoside, which is a polyphenol with numerous biological activities, including the ability to bind to the benzodiazepine binding site in GABA-A receptors of neurons, contributing to its potential anxiolytic effects [17]. The results of this intervention study will elucidate if this lemon verbena extract may help improve the sleep quality and reduce stress in healthy adolescents with reported poor quality of sleep and moderate stress.

2. Materials and Methods

2.1. Study Design and Participants

A randomized, double-blind, placebo-controlled, single-center intervention study was carried out, with two parallel arms (placebo and experimental product). This study was conducted at the Nutratech S.r.l. facilities (Rende (Cosenza), Italy). The aim of this study was to assess the efficacy of a food supplement in reducing stress and improving sleep quality in adolescents ages 12 to 16, consumed for 12 weeks. The primary endpoints were the Adolescent Sleep Wake Scale (ASWS), Perceived Stress Scale for Children (PSS-C), and cortisol levels. The secondary objectives were to assess the efficacy of the product as perceived by the parents/legal representatives of the subjects, as well as an evaluation conducted by a psychologist. The secondary endpoints consisted in questionnaires for the parents and a psychological evaluation of the results of the primary endpoints. In the case of the psychological evaluation, the possible answers to the question if the product was efficacious were as follows: completely disagree, disagree, agree, or completely agree.
Participants were recruited based on the following inclusion criteria: healthy female and male subjects, aged 12–16 years, with sleep and stress disturbances. Participants were excluded if they presented any disease or condition that may interfere with the study, are currently or planning to participate in other trials, had a food intolerance or allergy to any of the ingredients that the product may contain, and are under pharmacological treatment that may be incompatible with the study. The inclusion criteria for the parents include being adults, capable of understanding the language used during the study, are committed to respect the instructions given by the investigator, and will not change the daily routine of the minor.
The study protocol was approved by the Ethics Committee “Comitato Etico Indipendente per le Indagini Cliniche Non Farmacologiche” (ref. no. 2024/08 by 16 July 2024). All the participants provided written informed consent.

2.2. Herb Extract

A purified lemon verbena (Lippia citriodora) extract, standardized at a minimum 24% verbascoside and 28% total phenylpropanoids, was used as experimental product (provided by Monteloeder SL (Alicante, Spain)). The extract is commercially available under the brand name RelaxPLX® or PLX®, and its extraction process has been elucidated in previous publications [15,16]. The effective dose was 400 mg, divided into two capsules, taken 1 h before bedtime. The capsules with lemon verbena contained various excipients, such as calcium phosphate, microcrystalline cellulose, magnesium salt, and silicone dioxide. The placebo capsules contained the same excipients, except it included maltodextrin instead of the lemon verbena extract.

2.3. Randomization and Study Procedures

A total of 44 subjects were recruited and randomized using computer software, divided equally into placebo and experimental groups. The duration of the study was 12 weeks, with clinic visits at the beginning, week 4, 8, and 12 of the study. During the enrollment visit, the subjects were screened to confirm they met the inclusion criteria and signed an informed consent as well as authorization for the treatment of personal data. Also, they received a kit to collect and store the salivary samples. The subjects and parents were instructed to collect the saliva sample early in the morning on the day of the visit.
In the first visit, the saliva samples were collected, and the subjects completed the ASWS and PSS-C questionnaires. They were then provided with the capsules based on their designated group, receiving enough for 4 weeks, until the next visit. The kit for saliva sampling was also provided. This same procedure was repeated in the visits on weeks 4, 8, and 12. At the last visit, the parents completed the Parental Evaluation Questionnaire, and the psychologist evaluated the results of the questionnaires completed by the subjects to give their opinion on the effectiveness of the treatment. Any potential adverse events were also collected during each of the visits.

2.4. Study Variables

The subjects filled out two questionnaires: the ASWS and PSS-C [18,19,20,21]. The ASWS is a 28-item self-evaluation questionnaire used to assess sleep quality in subjects aged 12–18 years. The items describe the occurrence of different sleep behaviors and are grouped into 5 subscales: going to bed (5 items), falling asleep (6 items), maintaining sleep (6 items), reinitiating sleep (6 items), and returning to wakefulness (5 items). The respondents indicated how often sleep behaviors had occurred during the past month using the following six-point Likert scale: 1 = always, 2 = very often, 3 = quite often, 4 = sometimes, 5 = once in a while, and 6 = never. Eight items are reversed (Items 3, 4, 7, 11, 17, 23, 24, and 25). Mean subscale scores were calculated for each subscale and an ASWS total score was calculated as the mean of the 5 subscale scores. Higher scores indicate better sleep quality.
The PSS-C is a 13-item measure of a child’s perceived stress in several different areas including stress related to time, school, parent relationships, peer relationships, conflict, and feelings like fear, happiness, and anger. The form consists of 14 questions; the first one, which is not scored, checks that the child understands the response scale. Respondents answer on a four-option scale (never, a little, sometimes, or a lot) with scores ranging from 0 to 3. Seven questions (Numbers 3, 6, 7, 10, 11, 13, and 14) are scored in reverse. The total score ranges from 0 to 39, with higher scores indicating higher levels of perceived stress.
Besides these questionnaires, saliva samples were taken by the subjects in the morning that they attended the visits to assess cortisol levels. Salivary cortisol was performed by electrochemiluminescence (ECLIA) (Elecsys® Cortisol II) (Roche Diagnostics GmbH, Sandhofer Strasse 116, D-68305 Mannheim, Germany). The results are expressed in µg/dL.
Also, a Parental Evaluation Questionnaire consisting of 10 items was completed by the parents or legal guardian. The responders provided answers using an 11-point Numerical Rating Scale (NRS), ranging from 0 to 10 (0 being the lowest value and 10 the highest).
At the end of this study, a psychologist evaluated the results for each subject, providing a final opinion if the treatment was considered efficient. The question asked to the psychologist was “The treatment is efficacious”. The four possible answers are as follows: completely agree/agree/disagree/completely disagree.

2.5. Statistical Analysis

The values are presented as the mean and standard errors of the mean. The statistical analysis of the data was performed with JAMOVI version 1.6.23.0 statistical program (Sydney, Australia) and RStudio (Copyright © 2009–2024 Posit Software, https://cran.rstudio.com/, Boston, MA, USA). For the analysis of the Adolescent Sleep Wake Scale (ASWS) and the Perceived Stress Scale for Children (PSS-C): inter-group analysis was carried out using the Mann–Whitney U-test, except when analyzing the sex-specific results, in which case the ANOVA test was performed. For the analysis of cortisol levels, an inter-group analysis was carried out using the ANOVA (general linear model; 3 times, 2 groups). The significance level was set at p < 0.05.

3. Results

3.1. Participants

A total of 44 participants were recruited for this study, divided into placebo and experimental groups. One individual from the placebo group dropped out due to tachycardia, diarrhea, and nausea, while an additional individual from the experimental group dropped out for personal reasons. At the end, 42 subjects completed the study, 21 subjects per study group (Figure 1).
Details regarding the demographic variables of the subjects are depicted in Table 1.

3.2. Adolescent Sleep Wake Scale (ASWS)

The subjects completed the ASWS questionnaire at baseline and at the end of each month taking the supplement. The baseline values of the placebo and experimental groups were not statistically different (p > 0.05), confirming the homogeneity of the groups. However, starting at the first month of the trial, the results of the experimental group were statistically higher compared to the placebo, suggesting that the experimental product had a significant effect on this variable (Table 2). Furthermore, the results became more significant the longer the subjects consumed the experimental product.
When analyzing the results based on sex, it was observed that the male participants taking the experimental product presented significant improvements versus the placebo, starting at 2 months of intake. The females, on the other hand, presented significant improvements from the first month. Furthermore, their results were more significant versus placebo than the males. This suggests a more significant perception of improvement in sleep quality in the females compared to the males.
Therefore, it can be concluded based on these results that the experimental product significantly improved the subject’s perception of their sleep quality, being statistically significant from the first month of intake. Also, the females seemed to perceive a more significant improvement in sleep quality when taking the experimental product.
The questions are organized in five different categories: questions related to going to bed, questions on falling asleep, questions on maintaining sleep, questions on reinitiating sleep after awaking, and questions on returning to wakefulness. When analyzing the total population, the experimental group revealed significant improvements in all categories, starting at the first month of treatment. When analyzing based on sex, females improved starting at the first month in all categories, while males improved during the first month in questions related to falling asleep, maintaining sleep, and reinitiating sleep. Therefore, the results of this study suggest that the ingredient overall improves all the behaviors related to sleep, in both sexes, with females reporting an earlier significant improvement in questions related to going to bed compared to males.

3.3. Perceived Stress Scale for Children (PSS-C)

The subjects completed the PSS-C questionnaire alongside the ASWS mentioned in the previous section. Again, the homogeneity of the groups was confirmed at baseline (p > 0.05). The experimental group significantly reduced their PSS-C scores compared to the placebo, starting at the first month of the trial (Table 3). In this case, a reduction in the score suggests an improvement in their perception of stress. The results were more significant the longer the subjects consumed the experimental product.
The sex-based results indicated that there were no significant differences in the effects of the ingredient in perceived stress among the males and females. In both cases, significant differences versus placebo were detected after 2 months of intake and continued into the 3rd month. Since the statistical analysis of the whole experimental population indicated significant differences versus placebo at the first month, this could mean that the lack of significance during the first month when analyzing based on sex may be due to the low number of subjects per subgroup.
In this experiment, it can be concluded that the experimental product significantly improved the subject’s perception of their stress levels, being statistically significant from the first month of intake.
When analyzing the questions in the PSS-C independently, it was observed that the significant differences compared to the placebo and experimental groups were with the following questions: “In the last week, how often did you feel rushed or hurried?”, “In the last week, how often did you feel worried about being too busy”, “In the last week, how often did you feel scared or nervous” and “In the last week, how often did you get enough sleep?”. When analyzing based on sex, the males revealed a significant improvement only on the questions “In the last week, how often did you feel rushed or hurried?” and “In the last week, how often did you have enough time to do what you wanted?”. As for the females, significant difference versus placebo was detected with the question “In the past week, how often did you get enough sleep?”. This suggests that the ingredient, in the case of the females, may have a more significant effect on sleep than stress, while in males it seems to have a more noticeable effect on stress-related parameters.

3.4. Cortisol Levels

Cortisol levels were analyzed from saliva samples taken by the subjects at their homes during the morning they went to the clinic. The baseline values were not statistically different in placebo and experimental groups, confirming the homogeneity of the population (Table 4). The cortisol levels of the placebo group did not change throughout this study, whereas a significant reduction was detected in the experimental group after 3 months. This reduction was statistically significant compared to the placebo.
When analyzing the results based on sex, it was revealed that cortisol levels significantly decreased after 3 months of intake only in the females (p < 0.05). The males revealed a tendency to decrease, but did not reach significance levels.
Therefore, it can be concluded that the subjects taking the experimental product significantly reduced their stress, as detected by the reduction in cortisol levels. This corroborates the results observed in the PSS-C questionnaire.

3.5. Psychologist Evaluation of the Treatment Efficacy

A psychologist evaluated the results of the questionnaires completed by the subjects (PSS-C and ASWS) as well as the cortisol levels to determine if the treatment was efficacious in improving their sleep quality and reducing their stress. The psychologist was blinded from the treatment and was unaware if the subject was taking the placebo or the experimental product. As a result, the psychologist reported that only 19% of those taking the placebo seemed to obtain significant results in improving their sleep and stress, providing an “agree” answer, as opposed to 86% of the subjects taking the experimental product (Table 5). Of the 86%, the psychologist gave an “agree” answer to 62% of the subjects, and 24% “completely agree”.
Therefore, the final decision of the psychologist was that the experimental product was clinically effective in the majority of the subjects to improve their sleep quality and reduce their stress.

3.6. Parental Evaluation Questionnaire

The results of the parental evaluation at the end of this study are depicted in Table 6 and Table 7, corresponding to the results of the placebo and experimental groups, respectively. A total of 10 questions were completed by the parents/legal guardians, related to the sleep quality, stress, and mood of the subjects.
Overall, the majority of the responders in the placebo group gave a low score in all the questions, with a median score of 3 or 4 depending on the question. A score above 6 was considered a positive result. In the placebo group, only 5% of responders provided a positive answer to questions related to sleep, academic performance, and willingness to purchase the product.
As for the experimental group, the results were more spread out, with a median score of 5–7 depending on the question. The highest scores were obtained from the questions “How much do you think the supplement helps your child increase the average number of hours of uninterrupted sleep?” and “How much do you think the food supplement helps your child fall back asleep more easily if he/she wakes up during the night?”, suggesting that the product was more efficient in improving aspects related to sleep. The lowest score, with a median value of 5, was obtained with the question “How much do you think the food supplement helps to improve your child behavior at school?”, which could suggest that the product was less efficient in helping the subjects manage their mood during the day. However, approximately a third of the parents/legal guardians provided a positive response to questions regarding stress, behavior, emotional wellbeing, concentration, and even improvements in the subject’s academic performance.
The results of the parental evaluation were also analyzed based on the sex of the subjects. Overall, the results were similar in both cases, with all the answers being significantly higher in the experimental groups compared to the placebo group, and with no specific question standing out when comparing male and female subjects.

4. Discussion

This study revealed that a dietary supplement comprised of lemon verbena extract purified in verbascoside may help improve sleep quality and reduce stress in adolescents with sleep and stress issues. This study was conducted for 12 weeks, with significant improvements in the ASWS (for sleep) and PSS-C (for stress) questionnaires as early as during the first month of this study, compared to the placebo. This coincided with a significant reduction in cortisol levels in saliva, which is related to stress. Interestingly, a stronger effect particularly in sleep quality was perceived by the females. This has also been observed in a previous publication with the same extract [15].
Lemon verbena has been traditionally used for centuries due to its anxiolytic effects, as well as to treat various conditions, including fever, digestive discomfort, and insomnia [22]. The main active compound that is suggested to be responsible for the sleep- and stress-related properties is verbascoside [23]. Preclinical studies revealed that verbascoside binds to the benzodiazepine binding site in GABA-A receptors [17,24].
Previous clinical studies conducted with the ingredient revealed significant improvements in sleep- and stress-related parameters [15,16]; however, these studies were conducted in an adult population. In this respect, there are fewer studies conducted in children and adolescents. Adolescence particularly is for many a challenging period, and studies have shown that up to 60% of adolescents have sleep problems [25]. The World Health Organization reports that there is a high incidence of mental disorders in adolescents, with depression, anxiety and behavioral disorders being the leading causes of illness in this population [26]. In the more severe cases, this can lead to drug and alcohol abuse, self-harm, and suicide, and the effects of mental health issues during adolescence can extend to adulthood. The COVID-19 pandemic has exacerbated this behavior [27]. Therefore, it is vital to detect early and take prevent measures to avoid lasting consequences on this vulnerable population.
The current study was conducted in a single center in Italy. Studies assessing Italian children and adolescents reveal that approximately 50% sleep less than the recommended amount by the National Sleep Foundation [28]. Similar results have been observed in other countries, corroborating that poor sleep quality seems to exacerbate in this age group [29,30,31]. Longer screen times have been suggested to be one of the contributing factors. Besides this, studies conducted in Italy, Spain, and Portugal have revealed that there is still a lasting effect in children and adolescents from the confinement during COVID-19 [32]. Spain and Italy were more severely affected by the pandemic during the first wave, with strict confinements lasting several weeks. The referenced study reveals that children and adolescents in Italy still present significantly greater symptoms related to mood, behavior, sleep, and eating disturbances even 3 and a half years after the confinement, than compared to before the pandemic.
In this study, we evaluated the subjects with questionnaires that are specifically designed for children and adolescents; the ASWS for sleep quality and the PSS-C for stress. In the case of ASWS, previous studies have shown that this questionnaire strongly correlates with the Pittsburgh Sleep Quality Index (PSQI), which is the standard questionnaire used in adults [33]. The PSS-C, on the other hand, was designed to be used in children and have been extensively used since its development a decade ago for this specific population [34]. Therefore, the use of these instruments helps to obtain more relevant information pertaining to this specific population.
While the results of this study are noticeable, there are certain limitations that should be considered. For example, the low subject number caused certain parameters to lose statistical significance when analyzing the study groups based on sex. Also, more clinical measurements such as polysomnography or analyzing brain activity would have provided a more objective indication regarding the effects of the ingredient. Despite this, the perceptions of the subjects are important to address, and intergroup analysis revealed significant differences versus the placebo group, confirming the efficacy of the lemon verbena extract.

5. Conclusions

The findings of this study suggest that lemon verbena extract purified in verbascoside may help reduce stress and improve sleep quality in adolescents with sleep and stress issues. This study was conducted in a single center located in Italy. Statistical significance in improved sleep and stress scores was detected, starting at the first month of intake and coinciding with a reduction in cortisol levels. Furthermore, the results observed in the females participating in the study suggest significant improvements in sleep quality earlier than the males, which corroborates previous studies. Therefore, these results may suggest that lemon verbena extract could be a natural alternative to provide to adolescents that have difficulties in managing stress and reduced sleep quality, which is very common in this population.

Author Contributions

Conceptualization, J.J., N.C. and R.V.; methodology, J.J., R.V. and E.D.; validation, J.J., N.C., A.G. and R.V.; formal analysis, R.V.; investigation, O.I.P. and C.L.; resources, J.J. and F.A.; data curation, E.D.; writing—original draft preparation, J.J.; writing—review and editing, N.C., P.N., A.G., V.N. and R.V.; visualization, J.J. and R.V.; supervision, J.J., F.A. and R.V.; project administration, F.A. and R.V.; and funding acquisition, J.J. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee “Comitato Etico Indipendente per le Indagini Cliniche Non Farmacologiche” on 16 July 2024 (Approval reference: 2024/08).

Informed Consent Statement

Informed consent was obtained from all the subjects involved in this study.

Data Availability Statement

Data may be available upon request to the corresponding author.

Acknowledgments

We wish to thank the technical support received from Monteloeder and Complife.

Conflicts of Interest

Authors Pau Navarro, Adrián García, Nuria Caturla and Jonathan Jones were employed by the company Monteloeder SL. Authors Roberta Villa and Vincenzo Nobile were employed by the company Complife Italia S.r.l. Authors Fabio Amone and Erminia D’Ambrosio were employed by the company Nutratech S.r.l. This does not alter the author’s adherence to all the journal policies on sharing data and materials. The other authors declare no conflicts of interest. The funder had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

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Applsci 15 05856 g001
Figure 1. Participants flow diagram.
Figure 1. Participants flow diagram.
Applsci 15 05856 g001
Table 1. Baseline demographic characteristics of subjects.
Table 1. Baseline demographic characteristics of subjects.
VariablesPlacebo GroupExperimental Group
Number of subjects21 (50%)21 (50%)
Male/female (%)Male 6 (28.6%)Male 13 (61.9%)
Female 15 (71.4%)Female 8 (38.1%)
Age, years13.94 ± 1.0114.33 ± 1.08
Number participants per pubertal stage (pre/early/mid/late/post-pubertal)Pre-puberty 1 (4.8%)Pre-puberty 0 (0%)
Early puberty 0 (0%)Early puberty 2 (9.5%)
Mid-puberty 3 (14.3%)Mid-puberty 3 (14.3%)
Late puberty 11 (52.4%)Late puberty 11 (52.4%)
Post-puberty 6 (28.6%)Post-puberty 5 (23.8%)
Data are presented as n value and percentage for each variable, except for age which is the mean value and standard error.
Table 2. Results of the ASWS (Adolescent Sleep Wake Scale) score in the placebo and experimental groups at different time points. * p < 0.05, ** p < 0.01, *** p < 0.005, and **** p < 0.001 vs. placebo.
Table 2. Results of the ASWS (Adolescent Sleep Wake Scale) score in the placebo and experimental groups at different time points. * p < 0.05, ** p < 0.01, *** p < 0.005, and **** p < 0.001 vs. placebo.
Study GroupBaselineMonth 1Month 2Final
Placebo (total)3.2 ± 0.13.4 ± 0.13.4 ± 0.13.5 ± 0.1
Experimental (total)3.2 ± 0.14.1 ± 0.1 ***4.3 ± 0.1 ****4.5 ± 0.1 ****
Placebo (males)3.3 ± 0.13.5 ± 0.33.6 ± 0.23.4 ± 0.3
Experimental (males)3.3 ± 0.14.0 ± 0.14.2 ± 0.1 *4.4 ± 0.1 **
Placebo (females)3.2 ± 0.13.4 ± 0.33.4 ± 0.33.5 ± 0.4
Experimental (females)3.1 ± 0.14.2 ± 0.2 ****4.3 ± 0.2 ****4.6 ± 0.2 ****
Data presented as mean value ± standard error.
Table 3. Results of the PSS-C (Perceived Stress Scale for Children) score in the placebo and experimental groups at different time points. * p < 0.05, ** p < 0.01, and *** p < 0.001 vs. placebo.
Table 3. Results of the PSS-C (Perceived Stress Scale for Children) score in the placebo and experimental groups at different time points. * p < 0.05, ** p < 0.01, and *** p < 0.001 vs. placebo.
Study GroupBaselineMonth 1Month 2Final
Placebo18.2 ± 0.618.1 ± 0.717.9 ± 0.617.2 ± 0.7
Experimental18.0 ± 0.615.9 ± 1.0 *14.9 ± 0.8 **12.9 ± 0.8 ***
Placebo (males)17.7 ± 1.217.3 ± 0.917.8 ± 1.517.2 ± 0.9
Experimental (males)16.8 ± 0.614.3 ± 1.214.0 ± 1.0 *11.5 ± 0.7 ***
Placebo (females)18.5 ± 0.718.4 ± 0.817.9 ± 0.617.2 ± 0.9
Experimental (females)19.8 ± 0.818.4 ± 1.316.3 ± 1.1 **15.3 ± 1.3 *
Data presented as mean value ± standard error.
Table 4. Results of analysis of cortisol (in µg/dL) in the placebo and experimental groups at different time points. * p < 0.05 vs. placebo.
Table 4. Results of analysis of cortisol (in µg/dL) in the placebo and experimental groups at different time points. * p < 0.05 vs. placebo.
Study GroupBaselineMonth 1Month 2Final
Placebo0.56 ± 0.030.57 ± 0.040.57 ± 0.040.61 ± 0.05
Experimental0.57 ± 0.040.62 ± 0.030.54 ± 0.040.45 ± 0.03 *
Placebo (males)0.56 ± 0.060.55 ± 0.090.52 ± 0.050.58 ± 0.09
Experimental (males)0.51 ± 0.040.63 ± 0.050.49 ± 0.040.41 ± 0.03
Placebo (females)0.55 ± 0.040.59 ± 0.050.59 ± 0.060.62 ± 0.07
Experimental (females)0.68 ± 0.060.61 ± 0.050.63 ± 0.080.51 ± 0.05 *
Data presented as mean value ± standard error.
Table 5. Results of the analysis by the psychologist on the efficiency of the treatment to improve sleep quality and reduce stress.
Table 5. Results of the analysis by the psychologist on the efficiency of the treatment to improve sleep quality and reduce stress.
Result% Placebo Subjects% Experimental Subjects
Completely disagree29%0%
Disagree52%14%
Agree19%62%
Completely agree0%24%
Final decision if treatment is efficientDisagreeAgree
Data are presented as percentage of subjects with respect to the total number per group that the psychologist has given the corresponding result.
Table 6. Results of the Parental Evaluation Questionnaire completed by the parents/legal guardians of the subjects in the placebo group.
Table 6. Results of the Parental Evaluation Questionnaire completed by the parents/legal guardians of the subjects in the placebo group.
Placebo Group Results
No.Items% of Subjects per Each Score% of Subjects Answering > 6Median Value
012345678910
01How much do you think the food supplement improves the quality of your child’s sleep?0%5%14%19%24%29%5%5%0%0%0%5%4
02How much do you think the food supplement helps your child fall asleep more easily (reducing the time it takes to fall asleep)?0%5%14%29%19%29%0%5%0%0%0%5%4
03How much do you think the supplement helps your child increase the average number of hours of uninterrupted sleep?0%5%14%29%14%29%5%5%0%0%0%5%4
04How much do you think the food supplement helps your child fall back asleep more easily if he/she wakes up during the night?0%5%24%14%29%19%5%5%0%0%0%5%4
05How much do you think the food supplement improves your child’s morning behavior (reducing irritability and increasing energy)?0%10%24%19%29%5%14%0%0%0%0%0%3
06How much do you think the food supplement reduces your child’s stress and improves his/her emotional wellbeing?0%10%24%14%24%14%14%0%0%0%0%0%4
07How much do you think the food supplement helps to improve your child’s behavior at school?0%10%29%29%14%14%5%0%0%0%0%0%3
08How much do you think the supplement helps your child to concentrate better in class?0%10%33%24%14%14%5%0%0%0%0%0%3
09How much do you think the food supplement helps to improve your child’s performance and academic results at school?0%10%38%19%14%10%5%5%0%0%0%5%3
10Would you buy the product?10%19%14%24%10%14%5%0%5%0%0%5%3
Data presented as percentage of parents that have given the corresponding score to each individual question.
Table 7. Results of the Parental Evaluation Questionnaire completed by the parents/legal guardians of the subjects in the experimental group.
Table 7. Results of the Parental Evaluation Questionnaire completed by the parents/legal guardians of the subjects in the experimental group.
Experimental Group Results
No.Items% of Subjects per Each Score% of Subjects Answering > 6Median Value
012345678910
01How much do you think the food supplement improves the quality of your child’s sleep?0%0%0%5%14%14%24%10%19%5%10%44%6
02How much do you think the food supplement helps your child fall asleep more easily (reducing the time it takes to fall asleep)?0%0%0%14%10%10%19%10%24%5%10%49%6
03How much do you think the supplement helps your child increase the average number of hours of uninterrupted sleep?0%0%0%10%10%19%5%19%10%19%10%58%7
04How much do you think the food supplement helps your child fall back asleep more easily if he/she wakes up during the night?0%0%0%14%19%10%5%14%24%5%10%53%7
05How much do you think the food supplement improves your child’s morning behavior (reducing irritability and increasing energy)?0%0%0%10%19%10%24%5%14%10%10%39%6
06How much do you think the food supplement reduces your child’s stress and improves his/her emotional wellbeing?0%0%0%14%10%10%29%24%5%0%10%39%6
07How much do you think the food supplement helps to improve your child’s behavior at school?0%0%0%14%29%14%14%10%5%0%14%19%5
08How much do you think the supplement helps your child to concentrate better in class?0%0%0%14%24%10%24%10%5%5%10%30%6
09How much do you think the food supplement helps to improve your child’s performance and academic results at school?0%0%0%14%24%5%14%14%14%5%10%43%6
10Would you buy the product?0%0%0%5%24%10%19%0%29%5%10%44%6
Data presented as percentage of parents that have given the corresponding score to each individual question.
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MDPI and ACS Style

Navarro, P.; García, A.; Villa, R.; Nobile, V.; Parisi, O.I.; Lirangi, C.; Amone, F.; D’Ambrosio, E.; Caturla, N.; Jones, J. Lippia citrodora (Lemon Verbena) Extract Helps Reduce Stress and Improve Sleep Quality in Adolescents in a Double-Blind Randomized Intervention Study. Appl. Sci. 2025, 15, 5856. https://doi.org/10.3390/app15115856

AMA Style

Navarro P, García A, Villa R, Nobile V, Parisi OI, Lirangi C, Amone F, D’Ambrosio E, Caturla N, Jones J. Lippia citrodora (Lemon Verbena) Extract Helps Reduce Stress and Improve Sleep Quality in Adolescents in a Double-Blind Randomized Intervention Study. Applied Sciences. 2025; 15(11):5856. https://doi.org/10.3390/app15115856

Chicago/Turabian Style

Navarro, Pau, Adrián García, Roberta Villa, Vincenzo Nobile, Ortensia Ilaria Parisi, Chiara Lirangi, Fabio Amone, Erminia D’Ambrosio, Nuria Caturla, and Jonathan Jones. 2025. "Lippia citrodora (Lemon Verbena) Extract Helps Reduce Stress and Improve Sleep Quality in Adolescents in a Double-Blind Randomized Intervention Study" Applied Sciences 15, no. 11: 5856. https://doi.org/10.3390/app15115856

APA Style

Navarro, P., García, A., Villa, R., Nobile, V., Parisi, O. I., Lirangi, C., Amone, F., D’Ambrosio, E., Caturla, N., & Jones, J. (2025). Lippia citrodora (Lemon Verbena) Extract Helps Reduce Stress and Improve Sleep Quality in Adolescents in a Double-Blind Randomized Intervention Study. Applied Sciences, 15(11), 5856. https://doi.org/10.3390/app15115856

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