Melatonin Supplementation Improves Pain, Sleep Quality, and Total Plasma Antioxidant Capacity in Women with Fibrocystic Breast Disease: A Randomized, Double-blind, Placebo-controlled Trial

Abstract

Objective:

Fibrocystic breast disease (FBD) is a prevalent benign breast disorder primarily affecting women of reproductive age. Characterized by breast pain (mastalgia), cystic and solid breast lesions, and associated hormonal imbalances. Melatonin, a hormone produced by the pineal gland, exhibits potent antioxidant, anti-inflammatory, and has been shown to improve sleep quality and mental health in various clinical populations. These properties suggest that melatonin may be a promising therapeutic option for symptom management in women with FBD.

Methods:

This randomized, double-blind, placebo-controlled trial enrolled 66 women aged 18–40 years with FBD, diagnosed according to American Cancer Society guidelines, at Beheshti Clinic, Kashan University of Medical Sciences. Participants were randomized to receive either melatonin (6 mg/day; n = 33) or placebo (n = 33) for 12 weeks. Primary outcomes included breast pain severity and high-sensitivity C-reactive protein (hs-CRP), while secondary outcomes assessed sleep quality, depression, anxiety, and biomarkers of oxidative stress and inflammation, including total antioxidant capacity (TAC), malondialdehyde (MDA).

Findings:

After 12 weeks, melatonin supplementation resulted in a significant reduction in breast pain scores (P = 0.006) and improvement in sleep quality (P = 0.02) compared to placebo. Additionally, TAC was significantly increased in the melatonin group (P = 0.01). No significant differences were observed for depression, anxiety, serum hs-CRP, or MDA levels.

Conclusion:

Twelve weeks of melatonin supplementation (6 mg/day) significantly alleviates breast pain, enhances sleep quality, and improves antioxidant status in women with FBD. These findings support the use of melatonin as a safe and effective adjunctive treatment for FBD symptom management.

INTRODUCTION

Fibrocystic breast disease (FBD) is one of the most prevalent benign breast disorders, affecting approximately 40% of women in their reproductive years.[1] Despite its high incidence, the exact pathophysiological mechanisms of FBD remain incompletely understood. However, an imbalance in sex hormone levels, particularly an elevated estrogen-to-progesterone ratio, is widely considered a central factor in its development.[2] This hormonal dysregulation promotes excessive proliferation of mammary gland epithelial cells, leading to the formation of characteristic cystic and solid lesions, along with epithelial hyperplasia. These tissue alterations are accompanied by heightened levels of inflammatory mediators and oxidative stress markers, contributing to the clinical manifestations of FBD, most notably cyclic mastalgia (breast pain).[3]

Current therapeutic options for FBD include hormonal agents such as danazol and tamoxifen, which target the underlying hormonal disturbances.[3] Nevertheless, these pharmacological treatments are frequently associated with adverse effects that limit their long-term use and patient adherence. As a result, nonpharmacological interventions like vitamin E supplementation and evening primrose oil have gained attention as adjunctive therapies aimed at symptom alleviation, though their efficacy varies.[4,5]

Melatonin (N-acetyl-5-methoxytryptamine), a hormone secreted primarily by the pineal gland, has emerged as a promising candidate due to its potent antioxidant properties – reportedly up to four times stronger than vitamin E. Beyond its antioxidant capacity, melatonin exerts regulatory effects on reproductive hormones, modulating progesterone synthesis and luteinizing hormone receptor gene expression in ovarian granulosa cells.[6] It also influences cellular proliferation through inhibition of protein kinase A signaling pathways, which may have implications in controlling abnormal tissue growth.[7] Clinical studies have demonstrated melatonin’s ability to improve quality of life and reduce oxidative stress markers in a variety of conditions, including multiple sclerosis, coronary heart disease, and participants undergoing methadone maintenance therapy.[8,9] Furthermore, melatonin has shown anti-inflammatory and antioxidative effects in metabolic disorders such as obesity and metabolic syndrome and has shown protective effects against organ-specific toxicity and injury in multiple experimental models.[10,11]

Given the pathophysiological complexity of FBD and the limitations of existing treatment modalities, this study was designed to investigate the potential benefits of melatonin supplementation on breast pain (mastalgia), mental health parameters, inflammatory status, and oxidative stress in women with FBD. By exploring these endpoints, we aim to provide insight into melatonin’s therapeutic potential as a safe and effective adjunctive intervention for managing FBD symptoms and improving patient quality of life.

METHODS

Study design and participants

This randomized, double-blind, placebo-controlled clinical trial (registration number: IRCT20170513033941N59) was conducted at the Beheshti Clinic, Kashan University of Medical Sciences, Iran, between June and December 2019. Eligible participants were women aged 18–40 years diagnosed with FBD based on the criteria of the American Cancer Society.[12] The study was approved by the Ethics Committee of Kashan University of Medical Sciences (IR.KAUMS.MEDNT.1398.018) and conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants before enrollment.

Inclusion and exclusion criteria

Inclusion criteria: women aged 18–40 years with a confirmed diagnosis of FBD.

Exclusion criteria: history of breast cancer; use of tamoxifen, danazol, or bromocriptine within the last 3 months; presence of active infections; or use of any nutritional or antioxidant supplements during the preceding 3 months.

Sample size calculation

Sample size determination was based on expected mean differences in high-sensitivity C-reactive protein (hs-CRP) levels obtained from a previous clinical study.[13] Assuming α = 0.05, β = 0.2 (power = 80%), and a 20% anticipated dropout rate, a total of 66 women (33 in each group) were required.

Randomization and blinding

Participants were randomly assigned in a 1:1 ratio to receive either melatonin or a placebo using a computerized randomization system (https://ctrandomization.cancer.gov). Both participants and research personnel were blinded to treatment allocation. Placebo tablets were matched in shape, size, and composition to the melatonin tablets (starch-based). Adherence to melatonin or placebo treatment was evaluated through weekly telephone follow-ups and by counting the remaining capsules at each visit [Figure 1].

Figure 1.

CONSORT diagram of the study protocol, patient selection, and randomization. No serious adverse events were reported. Mild side effects, including fatigue, dizziness, abdominal pain, headache, and restlessness, were observed and constituted the primary reasons for participant withdrawal from the study

Intervention protocol

The treatment dosage and duration were adapted from the double-blind, placebo-controlled study by Mesri Alamdari et al., which showed beneficial effects of melatonin on oxidative stress and inflammatory parameters.[14] Although the study was initially registered with a dose of 10 mg/day, participants received 6 mg/day administered as two 3 mg immediate-release oral tablets (Simorgh Darou Attar Pharmaceutical Co., Iran) approximately 60 min before bedtime to correspond with the circadian rhythm. The dose adjustment was made to enhance safety and tolerability while retaining antioxidant and anti-inflammatory efficacy.[13,14,15,16,17] Participants in the placebo group received identical-appearing tablets.

Outcome measures

Primary outcomes were clinical indicators including breast pain severity and hs-CRP. Secondary outcomes included mental health scores, inflammatory and oxidative stress biomarkers: total antioxidant capacity (TAC), malondialdehyde (MDA).

Pain intensity was assessed using the visual analog scale (0–10). Psychological assessments included the beck depression inventory,[18] Beck Anxiety Inventory (BAI),[19] and Pittsburgh Sleep Quality Index (PSQI).[20] Anthropometric parameters such as height, weight, and body mass index (BMI) were measured by trained personnel at baseline and after 12 weeks using standard Seca equipment. All assessments for pain, sleep quality, depression, and anxiety were performed at baseline and at the end of the 12-week intervention period.

Fasting blood samples were collected at baseline and at the end of the intervention to determine hs-CRP (IBL kit), TAC (Cusabio Biotech), and MDA (thiobarbituric acid-reactive substances method).

Statistical analysis

A per-protocol analysis was conducted, and only participants who completed the intervention and posttreatment assessments were included in the final analysis. Individuals who discontinued participation or were lost to follow-up were excluded due to missing outcome data. Statistical analyses were performed using IBM SPSS Statistics for Windows, Version 17.0 (IBM Corp., Armonk, NY, USA). Data normality was assessed using the Kolmogorov–Smirnov test. Baseline and postintervention comparisons between groups were conducted using independent samples t-tests. All statistical tests were two-tailed, and a P < 0.05 was considered statistically significant.

RESULTS

Of the 66 participants, eight withdrew (five from the placebo and three from the melatonin group) due to mild adverse effects such as fatigue, dizziness, abdominal discomfort, and restlessness. Thus, 58 participants completed the trial (melatonin: n = 30, placebo: n = 28) [Figure 1].

No serious adverse events were reported. Mild side effects, including fatigue, dizziness, abdominal pain, headache, and restlessness, were observed.

Kolmogorov–Smirnov analysis indicated normal data distribution.

Table 1 shows baseline anthropometric variables, which did not differ significantly between groups. After 12 weeks, melatonin administration significantly reduced mastalgia (P = 0.006), improved PSQI sleep scores (P = 0.02), and elevated TAC (P = 0.01) compared to placebo. A lower Pittsburgh Sleep Quality Index (PSQI) score indicates better sleep quality, with higher scores reflecting poorer sleep. Thus, a reduction in PSQI score corresponds to an improvement in sleep quality. Melatonin had no significant effect on depression, anxiety, hs-CRP, or MDA levels [Table 2].

Table 1.

General characteristics of study participants

	Melatonin group n=30	Placebo group n=28	P a
Age (year)	30.7±7.2	29.7±4.0	0.51
Height (m)	157.11±4.7	161.9±6.3	0.13
Weight-baseline (kg)	75.15±4.3	79.11±9.5	0.66
Weight at the end of trial (kg)	75.15±8.8	76.12±8.1	0.78
BMI-baseline (kg/m2)	30.4±2.1	29.4±5.2	0.53
BMI at the end of trial (kg/m2)	30.4±4.4	29.4±4.3	0.51

Data are presented as mean±standard deviation. Statistical significance was set at P^a<0.05

Table 2.

Pain score, mental parameters and biomarkers of inflammation and oxidative stress at baseline and after the 12-week intervention with melatonin in patients with FBD

Variable	Melatonin group n=30		Placebo group n=28		P a
	Baseline	Week 12	baseline	Week 12
Pain score	5.7±1.9	4.2±1.7	5.8±2.0	5.6±2.0	0.006**
Depression score	16.1±4.4	13.2±4.0	16.5±3.7	14.3±4.0	0.11
Anxiety score	12.8±5.4	10.9±4.0	136.6±4.8	12.5±5.3	0.26
Sleep score	8.1±2.4	6.5±2.2	8.5±2.3	8.3±2.6	0.02*
Hs-CRP (mg/L)	4.0±2.9	3.4±2.8	3.6±2.6	3.8±3.2	0.31
MDA (mmol/L)	2.6±0.2	2.5±0.4	2.9±0.7	2.8±0.7	0.27
TAC (mmol Trolox/L)	732.7±66.9	796.8±96.6	865.3±186.4	835.9±239.8	0.01*

Hs-CRP: High-sensitivity C-reactive protein, MDA: Malondialdehyde; TAC: Total antioxidant capacity. 0=VAS means no pain. 10=VAS means the worst possible pain. Data are expressed as mean±standard deviation. Calculated by independent t-test between the two groups. Statistical significance was set at P^a<0.05. *P^a<0.05, **P^a<0.01

DISCUSSION

This study demonstrates that a 12-week supplementation with melatonin (6 mg/day) significantly reduces breast pain and improves sleep quality in women with FBD, accompanied by an increase in total plasma antioxidant capacity. However, no significant changes were observed in depression, anxiety, MDA, or hs-CRP levels.

The improvement in sleep quality is consistent with melatonin’s established role in regulating circadian rhythms and its sedative properties.[21] Previous research has reported melatonin’s efficacy in enhancing sleep quality across diverse populations, including women with polycystic ovary syndrome, children with atopic dermatitis, and participants undergoing methadone maintenance therapy. The absence of significant changes in depression, anxiety, and inflammatory markers may be attributed to the relatively short duration of intervention, small sample size, and the mild baseline psychological distress among participants. Previous clinical trials examining melatonin’s effects on mood and inflammation in populations with metabolic or psychiatric disorders have yielded mixed findings, suggesting that treatment duration, dosage, and baseline characteristics critically influence outcomes.[22,23,24]

Mechanistically, melatonin’s therapeutic effects in FBD appear to be multifactorial. Melatonin modulates hormonal activity pivotal to FBD by downregulating estrogen receptor alpha expression and inhibiting local estrogen synthesis through suppression of enzymes such as aromatase and 17β-hydroxysteroid dehydrogenase.[25] This hormonal regulation likely mitigates estrogen-driven breast tissue proliferation and cyst formation.[26]

In addition, melatonin exerts antiproliferative effects by decreasing proliferating cell nuclear antigen expression and promoting apoptosis via caspase-3 activation, thus contributing to normalization of breast epithelial cell turnover.[27] It also modulates key intracellular signaling pathways; for instance, melatonin restores phosphatase and tensin homolog expression, inhibiting the AKT pathway, which reduces proliferative and survival signaling implicated in breast hyperplasia.[28]

The antioxidant capacity of melatonin is particularly relevant in FBD, a condition associated with increased oxidative stress. Melatonin effectively scavenges reactive oxygen and nitrogen species and enhances the activity of endogenous antioxidant enzymes, as reflected by the observed increase in TAC.[29] Although systemic inflammatory marker hs-CRP remained unaltered, melatonin may exert localized anti-inflammatory effects by downregulating pro-inflammatory pathways such as cyclooxygenase-2/prostaglandin E2 and nuclear factor kappa B, thereby reducing oxidative damage and inflammation within breast tissue.[30,31]

Finally, melatonin’s influence on circadian and neuroendocrine systems may modulate pain perception and stress responses, potentially contributing to the alleviation of breast pain and overall symptom improvement.[32]

In summary, melatonin’s combined hormonal, antiproliferative, antioxidant, anti-inflammatory, and neuroendocrine actions provide a compelling biological basis for its beneficial effects in FBD. These findings support the potential utility of melatonin as an adjunctive treatment to improve symptoms and quality of life in women with FBD. Further investigations are warranted to elucidate the precise molecular mechanisms, optimize dosing regimens, and assess long-term outcomes in larger cohorts.

CONCLUSION

In summary, this study demonstrates that melatonin supplementation effectively reduces breast pain and enhances sleep quality in women with FBD, alongside increased antioxidant capacity. The therapeutic benefits of melatonin likely arise from its complex mechanisms, including modulation of hormonal pathways, antiproliferative effects, and its antioxidant and anti-inflammatory properties. These results support melatonin as a viable adjunctive therapy for symptom management and quality of life improvement in FBD. Further large-scale studies are needed to confirm these findings, optimize dosing protocols, and evaluate long-term safety and efficacy.

AUTHOR’S CONTRIBUTIONS

EA: Conceptualization, methodology, data collection, statistical analysis, drafting the manuscript. SS: Data collection, patient recruitment, clinical assessment, and critical revision of the manuscript. AA: Laboratory measurements, biochemical analysis, data interpretation. NM: Study design, supervision, validation of data, and manuscript editing. HS: Project administration, funding acquisition, and final approval of the manuscript. GM: Methodology, data collection, and statistical analysis. The manuscript was drafted and critically revised through collaborative efforts. All authors have reviewed and approved the final version.

Limitations

Two minor deviations from the registered protocol should be acknowledged. First, although stratified randomization based on age and BMI was recorded in the IRCT, simple computer-generated randomization was ultimately used. Given the relatively small sample size and the baseline similarity between participants, this change is unlikely to have introduced selection bias or affected group comparability.

Second, some secondary outcomes – namely, triglycerides, total cholesterol, insulin levels, and insulin resistance indices (e.g., HOMA-IR) – were initially listed in the trial registry but were not measured due to financial and logistical constraints. While this limits the evaluation of certain metabolic parameters, it does not affect the primary objective or main findings of the study.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

This study received financial support from the Research Council of Kashan University of Medical Sciences (Grant No. 98014).