top of page

Overnight Melatonin Concentration and Sleep Quality Are Associated with the Clinical Features of Polycystic Ovary Syndrome

October 2023

Evans AT, Vanden Brink H, Lim JS, et al. Overnight Melatonin Concentration and Sleep Quality Are Associated with the Clinical Features of Polycystic Ovary Syndrome. Biomedicines. 2023;11(10):2763. Published 2023 Oct 12. doi:10.3390/biomedicines11102763


It has been reported that women with polycystic ovarian syndrome (PCOS) have increased levels of circulating melatonin levels and impaired circadian rhythms. This pilot study, N=35, included women with a mean age of 28 who had been medically diagnosed with PCOS. The primary aim of the study was to determine if alterations in melatonin excretion impacted sleep quality for women with PCOS, and a secondary outcome was to determine if alterations in melatonin production were associated with the diagnostic features of PCOS.


Our comments/takeaway from the article

We have previously reported that circadian patterns and melatonin levels are altered in women and adolescents with PCOS. This recent pilot study adds to the existing evidence that a misalignment in the circadian rhythm and, therefore, reduced sleep quality is present in women with PCOS. Clinically, it would be prudent to assess for sleep concerns in this population of women. Further, melatonin’s role in ovarian function was also suggested, supporting a previous review we reported on.


Article summary

This pilot study, N=35, included women with a mean age of 28 years who had been medically diagnosed with PCOS, as defined by the 2018 International Guidelines for PCOS, meeting at least two of the three diagnostic criteria (menstrual irregularity, biochemical or clinical hyperandrogenism and/or polycystic ovarian morphology).


Assessments and measurements used:

  • Sleep quality was assessed using the validated questionnaire, Pittsburgh Sleep Quality Index (PSQI), where a score above 5 is associated with poor sleep quality.

  • Sleep measures were evaluated using a wrist-worn triaxial accelerometer, which was worn at night for 6 nights.

  • Urine collection (6-sulfatoxymelatonin) was completed during the first-morning void and in the evening (between 6-9 pm) for two consecutive days/nights.



  • Sleep variables did not differ as reported in the PSQI

  • As measured with the accelerometer, women with PCOS had significantly reduced weekend sleep efficiency compared to the control group (p=0.01).

  • The night-to-day melatonin ratio (N:D) and weekend sleep efficiency varied by PCOS status.

  • The follicle number per ovary (FNPO) was positively associated with overnight melatonin concentrations. The authors provided two possible reasons for this association 1) the severity of PCOS can associated with the degree of disruption in the circadian rhythm and may serve as a marker of the phenotypic severity of PCOS 2) increased melatonin excretion may be an indicator of ovarian inflammation, as PCOS is characterized by high oxidative stress and melatonin is a well-establish antioxidant.


“…in participants with PCOS, as sleep efficiency increased, the magnitude of the overnight MEL rise relative to the daytime was significantly blunted. This observation supports previous reports of circadian misalignment in this population.” 


Limitations Noted by Authors

  • The number of nights the accelerometer was worn varied per participants

  • Morning void times varied from 4 am to 12 pm

  • Urinary 6-sulfatoxymelatonin may overestimate circulating melatonin levels

  • Lack of subtyping to PCOS phenotypes

  • One participant reported obstructive sleep apnea during the completion of the study, which can interfere with sleep quality.



Article review completed by Kim Ross, DCN

Content reviewed by Deanna Minich, PhD

October 31, 2023

bottom of page