Sometimes being on your period can leave you completely exhausted. And yes, there’s bleeding involved. But that isn’t the only thing happening.

Hormone levels are shifting, sleep can be affected, cramps may be interrupting the day, and heavier bleeding can make things harder for some people.

The brain is responding to those hormonal changes too.

A Lot Is Happening in a Short Amount of Time

 

Estradiol and progesterone rise and fall throughout the menstrual cycle, and those changes reach beyond the reproductive system.

A 2024 study followed 60 naturally cycling women and found that the way different brain networks interacted changed across different phases of the cycle. The lowest dynamic complexity appeared during the early follicular phase, which includes the first days of menstruation.

In simple terms, different parts of the brain were not communicating and shifting in exactly the same way throughout the month. Researchers saw changes in networks involved in attention, emotion, movement, and cognitive functions.

That doesn’t mean the brain works worse during a period. It shows that the brain is responding to the hormonal changes happening across the cycle.

Scientists are still learning what those shifts mean for things like mood, focus, and energy. But knowing that the brain itself is part of all these changes gives a little more context to why some days can feel more exhausting.

 

Sleep and Bleeding Matter Too

 

For some people, sleep gets a little harder around menstruation. In one study, 29% of participants experienced more difficulty sleeping around their period. Cramps and other symptoms can also make it harder to get a full night of rest.

Bleeding can play a role too. Heavy menstrual bleeding can contribute to iron deficiency or anemia in some people, which can cause fatigue and weakness.

 

And Life Is Still Happening

 

All of this can be happening internally while the day itself looks completely normal.

You still go to work, make plans, answer messages, run errands, and keep moving through the day, with a lot more going on in the background than anyone can see.

So maybe feeling a little more tired makes sense. Drink some water, get some rest when you can, and give the day a little less pressure. 💚

 

References

1. Avila-Varela, D. S., et al. (2024). Whole-brain dynamics across the menstrual cycle: the role of hormonal fluctuations and age in healthy women.

2. Van Reen, E., & Kiesner, J. (2016). Individual differences in self-reported difficulty sleeping across the menstrual cycle.

3. American College of Obstetricians and Gynecologists (ACOG). Heavy Menstrual Bleeding.