From pubescence to menopause, people with ovaries and a uterus will likely menstruate. Menstruation changes the level of sex hormones in the body, which not only control and regulate the reproductive system, but also affect thinking, moods, behaviour, appetite and libido. The “Female Reproductive System” is often not taught well in general schooling and for those who were taught, they may have forgotten much of the detail, with the result that most people don’t know how their own bodies work and the effect this has on them.

What many people do not understand is how the reproductive cycle affects hormone levels, which directly affects how your brain neurology functions. There are two key points in the cycle where this can be felt, the Mid Cycle Crash and PMS, which in severe cases leads to PMDD (Pre-Menstrual Dysphoric Disorder).

Menstruation

The most common menstrual cycle is 28 days long. A variation between 25 to 30 days is considered to be within acceptable medical tolerance. If your menstrual cycle is outside of those on a regular basis, or frequently fluctuates significantly more than 4 or 5 days, then you should talk to your gynaecologist about this. If you don’t have a gynaecologist , talk to your GP and ask for one. While some GP’s are well educated and capable to handle odd reproductive issues, many are not – remember that GP stands for “General Practitioner” – they are not specialists.

This is a graph of how the six major hormones appear across the menstrual cycle, separated into the Follicular Phase and the Luteal Phase. The vertical graph for each hormone is adjusted for clarity and to indicate the strength of the effect on the person. For example, Testosterone typically peaks at 0.171 mg/L while Progesterone typically peaks at 25 mg/L, which is too large a scale difference to see if we didn’t adjust each hormone to be clear.

Essentially, the Luteinising Hormone and Follicular Stimulating Hormone regulate which part of your period phase you are in. Generally, they are not too important, so here is another graph without them being included.

Follicular Phase

The Follicular Phase (FP), is considered to begin when menstruation begins, and concludes at Ovulation.

Menses, AKA Menstrual Flow

Menstrual flow is the time of the cycle where you excrete the unused uterus lining. You will likely experience cramps and some minor pain. If you find that the cramps and pain are frequently so painful that they prevent you from doing things, you should get this assessed (details below). All of the hormones that regulate your menstrual flow are low, with FSH and LH rising.

At the start of the cycle, your primary sex hormones are near their lowest. Oestrogen and Progesterone have risen a little just after the low that triggers PMT and PMDD. Testosterone is on a slight rise, FSH (Follicle Stimulating Hormone) rises to around 2/3 of its peak monthly value white LH (Luteinizing Hormone) is dropping down. During this part of the cycle Oestrogen will begin to rise.

Typical Menstrual Flow

This commonly flows for between 4 to 6 days, however 2 to 8 days is considered within tolerance. The average is blood quantity over this time is around 30 mL of blood, about as much liquid as can be held in your hand that is slightly cupped with your fingers apart. The nominal range is from 0 mL to 80 mL (where 0 is no bleeding). In a more useful metric, if you need to change your tampon or pad more than every 2 hours, then you are likely bleeding heavily enough that you should talk to your doctor.

Menstrual clots (chunks) generally occur when the flow is heavy. They are more common during the first 2 days of menstruation, typically the heaviest part of a period.

Atypical Menstrual Flow

Greater than 80 mL and or flow that is greater than 8 days is considered concerning, and should be checked by your doctor. If this is occurring regularly and your doctor is not concerned, see the above section about “General Practitioner Doctors are not Specialists”.

For more information on this, consider this Heavy Periods link.

Managing Menstrual Flow

You can manage the excretions in a few ways, internal, external or combined. The most common four methods are tampons, menstrual cups, pads and menstrual pants.

For more information on these, check out A quick guide to the Menstrual Cycle 2023 PDF and Period Education.

Managing Menstrual Pain

During menstruation the muscles around your uterus will contract to help dislodge the uterine lining. This can cause some discomfort and occasional pain. The pain can be felt in the middle front of your torso, between your belly button and your pelvic bone or where most people have the top part of their pubic hair.

The nerve that helps you feel your uterus is shared by the muscles on either side of the spine at your lower back, leading to referred pain, where your uterus is uncomfortable and your brain mistakes the pain as being from your back. Your brain’s response to this referred pain is to shore up the spine by stiffening the muscles, which then fatigue and ache. You can relieve this by using heat, stretches and various pain relief medication (eg naproxen and ibuprofen). Additional areas you may be feeling frequent co-occurring referred pain is your upper inner thighs and your hips.

You should not be feeling intense pain, dizziness or nausea. If you find that you become non-functional because of these symptoms (such as wanting to stay in bed curled up in a pain ball, or that you find it hard to focus because of pain), then you should talk to your GP about seeing a gynaecologist for Dysmenorrhea (painful menstrual cramps). While this level of pain isn’t necessarily an indication that something is broken or medically concerning, it both may be that something is concerning and should be addressed, or there are more medical grade treatments available to decrease that pain if there is no health concern. These treatments are often a more specific range of pain medications (eg buscopan, celecoxib and Panadol Osteo).

Menstruation and Toileting

Many people will find that their faeces changes consistency during this period of time. If your stool becomes hard, pellet like or you are constipated, you can try eating fruit, dried fruit or taking a medical stool softener to keep your bowel flowing properly. If you find that your stool becomes soft and runny, perhaps even diarrhoea, then you may need to take some medical aid to help firm that back up. A good consistent stool is an important marker for a healthy gut system, and we need those nutrients.

End of Menses

Once your Menstrual Flow has finished, you should find that cramps and aches recede and your faeces return to normal. Generally, the cramps and aches recede prior to the end of flow, however a late cramp or some spotting (just a few drops of blood, not a flow) at the end is not too uncommon.

Ovulation

Ovulation is where the egg is released by the ovary approximately 14 days after the menstrual period. The range for ovulation is generally between 10 and 18 days, depending on the length of your regular period (if it is regular). The maximum fertility is a few days either side of ovulation as sperm can survive for a few days within the environment.

Middle of the Follicular Phase

Some people report that the week after menses and up to ovulation is when they feel the best: cognitively, emotionally and energy wise. Take a look below at Middle of the Luteal Phase for some discussion on this.

Luteal Phase

The Luteal Phase (LP) covers the part of the beginning of menses (menstrual flow) to Ovulation. In this time period a proto egg in the ovary is being developed into a functional egg on the end of a follicle. The proto egg is called an oocyte. You were born with all of the oocytes.

After releasing the egg, the follicle in the ovary folds in on itself becoming a corpus luteum, a cluster of cells that produces the sex hormones oestrogen and progesterone. The hormones induce the endometrial glands to begin producing the proliferative endometrium and later the secretory endometrium. This is where the fertilised egg, the embryo, can implant and grow.

We are not going to cover pregnancy in this article. It is important to know that the reproductive system cycle is focused on reproduction of the species, thus in humans the monthly cycle to prepare for fertilisation. Upon failure to fertilise, the Follicular Phase is triggered, which starts with menses.

LP has two mini phases that can affect mood and thinking, the Mid Cycle Crash and PMT, which in severe cases is PMDD (PreMenstrual Dysphoric Disorder – a period of odd behaviours, low cognition and heightened emotion). Both of these are characterised by a strong decrease in Oestrogen and Progesterone. The mechanism for the mood changes appears to be Dopaminergic, that is related to how Oestradiol affects Dopamine, Noradrenaline and Adrenaline.

A significant part of creating (synthesising) neuronal Dopamine, from which neuronal Noradrenaline and Adrenaline are subsequently made, is based on Oestradiol modulating the amount of neuronal Dopamine that is synthesised. This appears to be a direct correlation. That is, more Oestradiol in your body, the more your brain synthesises Dopamine.

Dopamine, Noradrenaline and Adrenaline are vital neurotransmitters.

• Dopamine runs your Executive Function (understanding the situation, solving problems, retaining information)
• Noradrenaline runs your mood by determining your level of current safety (safe = joy, content, relaxation / not safe = fear, anger and disgust), and thus what you should prioritise as the next task (task initiation)
• Adrenaline fuels the actions of tasks being done, whether that is cognitive of physical, and runs your emergency response system (Freeze, Fawn, Flight and Fight)

Oestrogen, Progesterone and Testosterone all break down into Oestradiol. During both the Mid Cycle Crash and PMT/PMDD, the availability of all three of these hormones is low, which leads to low Oestradiol, which leads to low Dopamine synthesis, which leads to decreased Executive Function, impaired Mood and difficulties with tasks.

• Acute Stimulatory Effect of Estradiol on Striatal Dopamine Synthesis, 1995
• ADHD, PMDD, Mid Cycle Crash and Hormone Interactions
• Dopaminergic System

PMT/PMDD and the Mid Cycle Crash are covered in more detail below.

Mid Cycle Crash

The Mid Cycle Crash is generally felt around 3 days after ovulation should have occurred. Research on the Mid Cycle Crash is sparse. Most people experience a drop in mood insignificant enough to shrug off and ignore, but some find that they experience 24 to 48 hours of marked decrease in mood, heightened mood reactivity and a decrease in cognition.

As you can see on the graph, this is a time of low hormones, often not as low as PMT (covered below), but in sharp contrast to the level before and after this point. If you did not ovulate, your follicle doesn’t become a temporary boosting endocrine system, which leads to a lower level of hormones, and thus mood and cognitive function.

While this does not affect most people, enough of my clients have noted a mood and functionality drop at this time of month that I have found it helpful to explain that this day or two of struggle is part of a natural hormone fluctuation and not due to some past trauma or personal incompetence. The clients who this affects have reported back to me that when they feel unexpectedly bad, they check their menstrual tracker, note that it is the Mid Cycle Crash, and are more easily able to shrug off the secondary self blame effects that they usually have. They switch mode for the remainder of the day to “being kind to myself” and pick things up the next day (or the day after that if they have the 48 hour version).

Knowing why you feel how you do helps the negative self talk be less bad.

We cover this in more detail in ADHD, PMDD, Mid Cycle Crash and Hormone Interactions.

Middle of the Luteal Phase

After Ovulation and a possible Mid Cycle Crash, and prior to PMT, Oestrogen and Progesterone are at their natural peak. Assuming a successful ovulation, the temporary endocrine site from the Corpus Luteum adds a bit of extra Oestrogen and Progesterone to the system. Oestradiol is at the highest natural level of the month and that means that Dopamine, Noradrenaline and Adrenaline are at optimal values, leading to quick thinking (cognition), stable mood and energy to act on wants.

Many people report this as the best days of their menstrual cycle.

There are some people who find that they feel best just prior to ovulation. This may indicate that high Progesterone is limiting the production of Dopamine. So long as you do not feel cognitively or emotionally compromised, this is not a thing that needs to be medically addressed.

There are some who can become manic in this phase, which can be mistaken for Bipolar Affective Disorder. This is addressed in more detail in ADHD, PMDD, Mid Cycle Crash and Hormone Interactions.

PMT and PMDD

PMT (Pre Menstrual Tension) or PMS (Pre Menstrual Stress), is a difficult time just prior to menstrual flow. As you can see from the graph, all of the hormones are at their lowest. If you recall from above, Oestradiol directly affects the amount of Dopaminergic Neurotransmitters you have, effecting your cognition, mood and behaviour, and this time is month has the lowest Oestradiol level. During this phase, it is harder to think, mood is dysregulated, appetite is altered (often Dopamine chasing – aka junk food, or food avoidant), stool (faeces) often hardens but sometimes becomes loose (period poops), libido drops and decision making is poor.

For some, especially if you have ADHD, you can experience a severe effect to your cognition, mood and behaviour, leading to problematic behaviours as you lose or struggle to have conscious control of your choices. To make good choices, you need sufficient Dopamine in your Prefrontal Cortex and the right level of Noradrenaline in your Amygdala. Without those, your understanding is poor and your mood can’t be trusted. This is called Premenstrual Dysphoric Disorder (PMDD), which is covered in detail on our PMDD page.