Circadian rhythm is an oscillation phenomenon with a cycle of about 24 h, also known as biological clock. The function of female reproduction depends on the synchronization of the biological clock signal of the hypothalamus-pituitary-ovarian (HPO) axis.
Demographic data show that staying up for a long time, shift work and flying across time zones can cause women’s circadian rhythm disorders, which are related to menstrual disorders and adverse pregnancy outcomes
Melatonin is the hormones that induces sleep. Melatonin is required for ovarian function, especially for the follicular maturation. It is suppressed by artificial light thereby leading to disturbed sleep and the affected circadian rhythms also disturb the ovarian function resulting in hormonal imbalance.
Melatonin is produced mainly by the pineal gland. In addition to this, the oocytes (cells in the ovaries) secrete small quantities of melatonin. Hence, the existing PCOS which affects the oocytes further disturbs sleep. It is a vicious cycle.
Studies have confirmed that PCOS patients are more likely to suffer from sleep disorders such as drowsiness and obstructive sleep apnea (2). Recently, many evidences have further confirmed the relationship between circadian rhythm disorders and PCOS
Insomnia is defined as impairment in the ability to initiate or maintain sleep, including extended periods of wakefulness during the night. Chronic insomnia disorder is diagnosed when insomnia occurs at least three nights per week and for at least three months. Sleep disturbances and disorders have repercussions for daytime mood, cognition and psychomotor functioning, which acutely affect well-being and daily activities, and can inhibit productivity
Decreased sleep is associated with increased levels of cortisol (the stress hormone), insulin resistance, obesity, increased levels of anxiety and mood disorders and more unhealthy behaviors like smoking or drinking
References-
1. Li, H., Liu, M. & Zhang, C. Women with polycystic ovary syndrome (PCOS) have reduced melatonin concentrations in their follicles and have mild sleep disturbances. BMC Women’s Health 22, 79 (2022). https://doi.org/10.1186/s12905-022-01661-w
2. Thannickal A, Brutocao C, Alsawas M, Morrow A, Zaiem F, Murad MH, Javed Chattha A. Eating, sleeping and sexual function disorders in women with polycystic ovary syndrome (PCOS): a systematic review and meta-analysis. Clin Endocrinol (Oxf). 2020;92(4):338–49.
3. Li S, Zhai J, Chu W, Geng X, Chen ZJ, Du Y. Altered circadian clock as a novel therapeutic target for constant darkness-induced insulin resistance and hyperandrogenism of polycystic ovary syndrome. Transl Res. 2020;219:13–29.
4. Fernandez RC, Moore VM, Van Ryswyk EM, Varcoe TJ, Rodgers RJ, March WA, Moran LJ, Avery JC, McEvoy RD, Davies MJ. Sleep disturbances in women with polycystic ovary syndrome: prevalence, pathophysiology, impact and management strategies. Nat Sci Sleep. 2018 Feb 1;10:45-64. doi: 10.2147/NSS.S127475. PMID: 29440941; PMCID: PMC5799701.