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Why am I sad: the link between your cycle and your mood

That wave of sadness that arrives without warning often has concrete causes, and your emotions deserve to be heard.

4 min read

Some days, sadness arrives without warning, with no obvious reason. What you feel is real, and there are concrete reasons for it. About 75% of women experience at least one premenstrual symptom, often an emotional one. Understanding the link between your cycle, your body, and your mood is already a way of caring for yourself.

Before your period, falling estrogen lowers serotonin

Your brain regulates your mood with a chemical messenger called serotonin (often called the well-being molecule). Its production depends directly on your hormones, especially estrogen.

During the first half of your cycle, estrogen rises and supports serotonin. Your mood is often more stable. Then, in the days before your period, estrogen drops, and serotonin falls with it [1] [2].

This drop is not a malfunction: it's the normal working of your cycle. But its effects are very real, sudden sadness, the urge to cry, irritability, fatigue. About 75% of women of reproductive age feel at least one premenstrual symptom [2].

Understanding that it's hormonal is not the same as being told it's "just" hormonal. Your tears before your period are not a whim. Your brain is reacting to a real biochemical change.

Sources (2)
  • [1] Epperson CN, Steiner M, Hartlage SA, et al. Premenstrual Dysphoric Disorder: Evidence for a New Category for DSM-5. American Journal of Psychiatry. 2012;169(5):465-475. doi:10.1176/appi.ajp.2012.11081302
  • [2] American College of Obstetricians and Gynecologists (ACOG). Clinical Practice Guideline No. 7: Management of Premenstrual Disorders. Obstet Gynecol. 2023;142(6):1516-1533. doi:10.1097/AOG.0000000000005426

PMS, PMDD, or depression: tracking your emotions brings clarity

Feeling sad before your period does not mean you are depressed. But sadness that takes over everything and returns every cycle deserves attention.

Classic premenstrual sadness appears a few days before your period and eases soon after. It is part of premenstrual syndrome (PMS), which affects about 75% of women [2].

Premenstrual dysphoric disorder (PMDD) is a far more intense form. It affects 3 to 8% of women of reproductive age, with the DSM-5 citing 1.8 to 5.8% under strict criteria [1] [3]. Deep sadness, despair, crying spells, extreme irritability: these symptoms disrupt work, relationships, and sleep. It is not a lack of willpower [3].

Depression, by contrast, does not follow the cycle. It sets in continuously for at least two weeks, whatever the time of month [4]. In France, women are about twice as affected as men [5].

A simple marker: note your emotions over two to three cycles, and mark your period. If sadness returns in the luteal phase (the 14 days before your period) then fades, that points to PMS or PMDD. If it's there all the time, it may suggest depression [2] [4].

Sources (5)
  • [2] American College of Obstetricians and Gynecologists (ACOG). Clinical Practice Guideline No. 7: Management of Premenstrual Disorders. Obstet Gynecol. 2023;142(6):1516-1533. doi:10.1097/AOG.0000000000005426
  • [1] Epperson CN, Steiner M, Hartlage SA, et al. Premenstrual Dysphoric Disorder: Evidence for a New Category for DSM-5. American Journal of Psychiatry. 2012;169(5):465-475. doi:10.1176/appi.ajp.2012.11081302
  • [3] American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Arlington, VA: American Psychiatric Publishing; 2013.
  • [4] Haute Autorité de Santé (HAS). Épisode dépressif caractérisé de l'adulte : prise en charge en soins de premier recours. Recommandation de bonne pratique. 2017.
  • [5] Santé publique France. Baromètre Santé 2021 : prévalence de la dépression en France.

With a chronic illness, sadness has a biological basis

With a chronic illness, fatigue wears down more than the body. It also weighs on your morale, your patience, your motivation. Endometriosis, for example, affects about one in ten women in France, or 1.5 to 2.5 million women [6].

It is not "just painful periods." It is a chronic inflammatory disease, with pelvic pain, deep fatigue, and digestive issues [7]. And this inflammation doesn't stay in the body: it sends the brain signals that disrupt serotonin, through the inflammation-depression axis [8].

As a result, women with endometriosis have a risk of depressive symptoms about 1.5 times higher than the general population [8]. On top of that comes the wait: the average time to diagnosis is seven years in France [9]. Seven years of unrecognized pain is exhausting in itself.

There are also griefs no one names: spontaneity, an easy social life, sometimes a plan for parenthood. The anger and sadness you feel are not weakness. They are healthy responses to an abnormally hard situation. Your emotional pain is not "all in your head": rejection and distress partly activate the same brain regions as physical pain [10].

Sources (5)
  • [6] INSERM. Endométriose. Dossier d'information. 2022. / Ministère de la Santé. Stratégie nationale de lutte contre l'endométriose. Janvier 2022.
  • [7] ESHRE (European Society of Human Reproduction and Embryology). Guideline on Endometriosis. 2022.
  • [8] Chen LC, Hsu JW, Huang KL, et al. Risk of developing major depression and anxiety disorders among women with endometriosis: a longitudinal follow-up study. Journal of Affective Disorders. 2016;190:282-285. doi:10.1016/j.jad.2015.10.030 / Laganà AS, La Rosa VL, Rapisarda AMC, et al. Anxiety and depression in patients with endometriosis: impact and management challenges. International Journal of Women's Health. 2017;9:323-330.
  • [9] EndoFrance / Haute Autorité de Santé (HAS). Prise en charge de l'endométriose : recommandations. Décembre 2017.
  • [10] Eisenberger NI. The neural bases of social pain: evidence for shared representations with physical pain. Psychosomatic Medicine. 2012;74(2):126-135.

Seeing a professional is not an overreaction: where to start

Seeing a professional about sadness, whether it's tied to your cycle or an illness, is not an overreaction. It is care, like seeing a doctor for knee pain. Several professionals can support you.

  • Your doctor or gynecologist: often the first door. They can assess your symptoms, adjust hormonal treatment if needed, and refer you [11] [2].
  • A psychologist: cognitive behavioral therapy (CBT, work on thoughts and behaviors) helps with cycle-related sadness and the emotional impact of chronic illness [12].
  • A psychiatrist: they can make a diagnosis and prescribe if needed. For PMDD, SSRI antidepressants (which raise available serotonin) are the first-line treatment, continuously or only in the luteal phase [1].

In France, the Mon soutien psy program reimburses sessions with a psychologist, on your doctor's referral [13]. Community Mental Health Centers (CMP, public mental-health clinics) offer free consultations. The association EndoFrance guides women affected by endometriosis.

Adapted physical activity (walking, yoga, swimming) is a recognized complement: it reduces mild to moderate depressive symptoms and improves sleep [14]. Not a push to "move more," just an option, at your own pace.

Sources (6)
  • [11] NICE (National Institute for Health and Care Excellence). Depression in adults: treatment and management. NICE Guideline NG222. 2022.
  • [2] American College of Obstetricians and Gynecologists (ACOG). Clinical Practice Guideline No. 7: Management of Premenstrual Disorders. Obstet Gynecol. 2023;142(6):1516-1533. doi:10.1097/AOG.0000000000005426
  • [12] Kleinstäuber M, Witthöft M, Hiller W. Cognitive-behavioural and pharmacological interventions for premenstrual syndrome or premenstrual dysphoric disorder: a meta-analysis. J Clin Psychol Med Settings. 2012;19(3):308-319.
  • [1] Epperson CN, Steiner M, Hartlage SA, et al. Premenstrual Dysphoric Disorder: Evidence for a New Category for DSM-5. American Journal of Psychiatry. 2012;169(5):465-475. doi:10.1176/appi.ajp.2012.11081302
  • [13] Ministère de la Santé. Dispositif Mon soutien psy (anciennement MonParcoursPsy). 2022.
  • [14] Daley A. Exercise and premenstrual symptomatology: a comprehensive review. Journal of Women's Health. 2009;18(6):895-899.

What you feel is real: not weakness, not exaggeration. Your sadness has biological, psychological, and sometimes social explanations. Understanding it doesn't make everything disappear, but it changes one thing: it's not "all in your head." You have the right to be heard and supported, at your own pace. Tracking your mood across your cycles can help you talk about it with a professional.

This article is for information only and does not replace the advice of a health professional. If a symptom worries you, talk to a doctor.

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