The average length of the menstrual cycle is 28 days – though this can vary from woman to woman, or from cycle to cycle to between 24 – 38 days. Each cycle is characterised by fluctuating levels of reproductive hormones e.g. oestrogen, progesterone, follicle-stimulating hormone (FSH) and luteinising hormone (LH).1,3

Phases of the menstrual cycle1

Menstrual phase: This phase begins on the first day of bleeding (also referred to as the start of your period). During this phase, which lasts for an average of 5 days, the extra lining of your uterus (that was formed in preparation for pregnancy) sloughs off and is discarded by your body.
Follicular phase: Starts on the first day of your period and lasts for about 13 days. This phase involves the development of an egg cell inside a follicle within your ovaries.
Ovulation phase: Happens on day 14 (in a 28-day cycle), when a mature egg is released from one of your ovaries.
Luteal phase: Lasts for about 14 days after ovulation. If you do not become pregnant, this phase ends with menstruation and the start of a new cycle.

How oestrogen and progesterone levels fluctuate during your menstrual cycle1,2,3

Each phase of your menstrual cycle occurs in response to changes in the levels of your reproductive hormones. Oestrogen and progesterone levels are low during menstruation. Oestrogen levels increase rapidly during the remainder of the follicular phase, then drop off after ovulation occurs, before increasing slightly during the luteal phase. Progesterone gradually increases during the follicular phase and peaks during the luteal phase. Both oestrogen and progesterone levels drop substantially during the luteal phase (leading up to your next period) if pregnancy does not occur. The decline in oestrogen and progesterone in the days before your period can affect how you feel both physically and emotionally. Progesterone, specifically, has been linked to sleep problems in the latter part of the luteal phase.

Sleep and your menstrual cycle1,2,4

The follicular and early luteal phases of your menstrual cycle are accompanied by longer durations of deep sleep compared with the time around your period. Most sleep disturbances, attributed to decreasing progesterone levels, tend to occur in the luteal phase. Women in their luteal phase complain of insomnia (in the latter part of the luteal phase), taking longer to fall asleep, more sleep interruptions (i.e. awakenings during the night), lower sleep quality and lower sleep efficiency (ratio of total sleep time to time spent in bed). Dips in your body temperature a bit before, and during the night, help you fall asleep faster and promotes deeper sleep. Your core body temperature (related to progesterone levels) increases during the luteal phase, making it harder to fall asleep and reducing the quality of your sleep (causing fragmented/interrupted sleep).1,2,4,5 Learn more about insomnia6

Some women experience premenstrual syndrome (PMS) during the luteal phase of their menstrual cycle. PMS includes symptoms like bloating, pelvic or muscle pain, stomach-ache, backache, headaches, breast tenderness and sleep problems. Women with PMS are at least twice as likely to suffer from insomnia during their period. If you suffer from PMS, you may also experience more unpleasant dreams, interrupted sleep (waking up during the night), morning tiredness and daytime sleepiness.1,4,5

Tips for improving your sleep before your period1

Regular exercise, a healthy diet, relaxation techniques and drinking enough water may help to alleviate the symptoms of PMS. Speak to your doctor if your PMS symptoms, including sleeping problems, are particularly bothersome. She/he may prescribe medication or nutritional supplements for your more severe symptoms that could help improve your sleep.

Many women find that their PMS symptoms decrease or go away within a day or two of their period starting. This gives you the opportunity to focus on developing healthy sleep habits that may help you achieve regular, restorative sleep and reduce sleep disruptions before and during your subsequent periods.1


We’ve created a booklet filled with useful tips to help you manage your insomnia6

In preparing this article, every effort has been made to provide an objective overview. The content contained in this article contains medical or health sciences information as per cited articles for public information. The content of this article has been initiated and is brought to you by Sanofi South Africa.


1. Suni E, Vyas N. PMS and insomnia. 04 May 2023. Sleep Foundation. Available online at [Accessed 30 June 2023].

2. Haufe A, Leeners B. Sleep disturbances across a woman’s lifespan: What is the role of reproductive hormones? J Endocr Soc 2023;7:1-14.

3. Welt CK. Normal menstrual cycle. 17 April 2023. UpToDate. Available online at [Accessed 30 June 2023].

4. Dorsey A, de Lecea L, Jennings KJ. Neurobiological and hormonal mechanisms regulating women’s sleep. Front Neurosci 2021;14:1-21. doi: 10.3389/fnins.2020.625397.

5. Brody B. PMS and sleep: What’s the connection? 23 March 2022. WebMD. Available online at [Accessed 30 June 2023].

6. Tips to help you overcome insomnia and get the sleep you need. Patient resource. Sanofi. MAT-ZA-2100751-1.0-07/2021.