If you have a monthly cycle, you’re already intimately familiar with the highs and lows of your period. What may not be as obvious are the subtler physiological changes that occur during your cycle.
By monitoring a few key signals from your body, you can predict hormone shifts ahead of time and prepare accordingly.
Menstruation is broken down into three hormone phases centered around ovulation: pre-ovulation (follicular), ovulation, and post-ovulation (luteal).
Your follicular phase refers to the fact that each of your eggs is contained in a sack known as a follicle. At the start of your cycle, one follicle starts growing faster than the others to prepare for the release of an egg.
Your follicular phase begins with your period. Your levels of estrogen and progesterone are low and, as a result, the top layers of your uterine lining break down and are shed in the form of menstrual bleeding.
As the follicular phase continues, your estrogen levels rise and your uterine lining gradually rebuilds. This phase lasts about 14 days and prepares your body for potential conception.
Approaching your ovulation phase, your body builds up momentum to release an egg in the midpoint of your cycle. For 16 to 32 hours, your body has a surge of estrogen, follicle-stimulating hormone (FSH), and luteinizing hormone (LH), which triggers your egg release from your ovary.
As you enter your luteal phase, your now-empty follicle transforms into a luteal body, a mass of cells that produce progesterone to support the next step in your cycle.
During your luteal phase, your FSH and LH levels decrease. Your body turns its attention to increasing progesterone and estrogen levels, thickening the lining of your uterus as a landing pad for a fertilized egg.
If the egg is not fertilized, progesterone and estrogen drop off again after 14 days and your cycle restarts. If the egg is fertilized, progesterone rises and your body prepares for pregnancy.
All of these changes can greatly impact how you feel day to day. During the late luteal phase (about a week before menstruation), the rapid decline in both estrogen and progesterone hormones starts to negatively manifest itself. This is the time when many women may experience breast tenderness, fluid retention, bloating, cramps, cravings, mood swings, tiredness, or anxiety.
You can predict the timing of various phases in your personal cycle by the way that hormone fluctuations impact your body temperature, heart rate, sleep, and respiration. Keep in mind that certain types of hormonal birth control will disrupt this pattern.
Here are some patterns to look for:
Estrogen lowers your average body temperature while progesterone raises it. In your follicular phase, estrogen levels are building and spike during ovulation. In your luteal phase, progesterone levels overtake estrogen.
The typical pattern results in low and variable temperatures in the first half of your cycle, followed by an increase within a day or two after ovulation. It remains elevated until your next period begins.
This pattern won’t look the same for every woman or every cycle. The majority of cycles, however, will show this overarching pattern: lower in the first half, higher in the second.
Your heart reflects the activity of your autonomic nervous system, which is made up of your rest-and-digest and fight-or-flight systems.
During your follicular phase, activity in your rest-and-digest system typically increases. This increase generally results in a lower resting heart rate (RHR) and higher heart rate variability (HRV).
In your luteal phase, there’s higher engagement in your fight-or-flight system. This pattern resembles strain in your body’s physiological reaction and typically results in an elevated RHR and lower HRV. There can be a lot more variability during the luteal phase between women based on the intensity of their symptoms.
The phase of your cycle can also impact your sleep. The late luteal phase is associated with lower sleep efficiency, a higher number of awakenings, and fragmented sleep. Additionally, women who are undergoing menopause may be at an even greater risk of disrupted sleep or insomnia due to hormone disruption and hot flashes, which can cause awakenings.
Circulating hormones also impact your lungs. Respiration is slower at the beginning of your cycle and speeds up as you enter the second half. Some women may find that respiratory symptoms, including asthma or shortness of breath, are impacted by the strain of their luteal phase.
Research on the female reproductive system and health is lacking. There’s a lot more work to be done for science to catch up with the complexity of your body. Given the lack of trusted resources available, it can be helpful to track your own observations and try to draw conclusions from your own experiences. Keeping a watchful eye on your cycle could give you an edge as you discover when it’s a good time to push hard or when it’s time to pull back and rest.
Consider tracking your phases in a calendar that you can compare with your body’s signals.
If you’re looking to conceive, you can use fertility tracking methods that require you to take daily oral temperature recordings or become more in touch with your rhythms using the Oura smart ring, which offers a simple way of measuring your temperature, respiration, and heart rate.
Be the captain, take the helm, and own your cycle.