If you feel extreme fatigue before your period or during your period, it’s not in your head. Here’s 6 biology-based reasons behind period fatigue — plus 3 tips to help you sleep better.
If you’ve ever dragged yourself through the week of your period wondering why you’re so exhausted, you’re not being dramatic. And you’re definitely not alone — the question “period causing fatigue?” was searched nearly 2,000 times just in the last month.
The truth is, your body is doing a surprising amount of behind-the-scenes work. The week leading up to when your period starts and the days of your period, it’s essentially running a partial remodel featuring rapid hormonal fluctuations, inflammation, blood loss, and more.
Read on for 6 biological reasons period fatigue is very real and 3 tips to help safeguard your nights from sleep problems during your period.
P.S. Sleep becomes even more important during your period — so try to get more of it, not less!
6 reasons you feel more tired on your period
#1 Progesterone drops steeply, affecting deep sleep
Progesterone builds up over the course of your cycle to help thicken and maintain the uterine lining in preparation for pregnancy. Right before your period in the late luteal phase, if a pregnancy does not occur, progesterone drops sharply.
Alongside supporting the uterine lining, progesterone has mild sedative effects and is linked with deep sleep. So when progesterone falls in the days leading up to your period, sleep can get stuck in lighter stages and you may experience more wake-ups, leaving you more fatigued.
#2 Prostaglandins increase to shed the uterine lining
You might be most familiar with prostaglandins for their role in everyone’s favorite period symptom: menstrual cramps. Prostaglandins increase before and during your period to trigger muscle contractions that help the body shed the uterine lining. The increased prostaglandins are technically a form of healthy inflammation, but a side effect can be body-wide fatigue — like the fatigue you feel when you catch a bad flu.
#3 Blood loss reduces iron
Iron is essential for transporting oxygen throughout the body and cellular energy production. Even a small drop is linked with energy crashes and exhaustion. Menstrual bleeding, particularly with heavy periods, temporarily reduces iron in the body, affecting how much energy you have on a cellular level.
#4 Estrogen drops to its lowest point
Estrogen supports two key areas related to sleep and energy: mitochondrial energy production and dopamine activity. The mitochondria is known as “the powerhouse” of the cell, converting nutrients into stable, usable sources of energy. In other words — it’s critical to energize the body. When estrogen falls, so does your cellular energy.
Estrogen also supports the dopamine production, release, and receptor sensitivity, and prevents its breakdown. Dopamine is linked with focus, pleasure, and cognitive function, so when estrogen drops during our periods, energy and alertness naturally fall with it.
#5 Increased body temperature makes it harder to sleep
Researchers have found that, to achieve stable, high-quality sleep, the body’s core temperature needs to drop 1-2° F. During the luteal phase (right before your period), it’s normal for core body temperature to rise 0.5-1° F. This subtle shift can have a surprisingly big impact on your nightly rest, making it harder to fall asleep, stay asleep, and keeping you in lighter, less restorative stages of sleep.
#6 Pain itself is draining
You might think pain is just pain, but it takes a real toll on the body. Pain actively increases stress hormones and energy expenditure, alongside directly disrupting sleep. Added to the mental fatigue that comes with cramps, headaches, and back pain, you can experience a major tax on nervous system processing that worsens fatigue.
3 Tips to Protect Your Sleep on Your Period
1. Get to bed a bit earlier
It’s okay to sleep more during your period! With your body working harder than usual, even 30-60 extra minutes of sleep can make a real difference in how you feel. Try shifting your bedtime earlier for the 3-5 days around your period — just to give your body some extra downtime for recovery while it’s expending more energy than usual.
2. Turn up the AC
Temperature can be tricky when you’re on your period — with core body temperature naturally higher by 0.5-1° F, it can feel like you’re stuck between overheating and shivering from cold sweats. Try setting the AC a bit lower to compensate for the increase in body temp, and keep a nice, breathable blanket or comforter nearby in case you get hit with the chills. (Researchers say the golden spot is 65-68° F, but play around to find your sweet spot!)
3. Wind down with heat
A warm shower or heating pad before bed does double duty: it soothes cramps and actually helps trigger the drop in core body temperature your body needs to fall asleep. The warmth on your skin draws blood to the surface, which then releases heat — helping you cool down from the inside for deeper, more restorative sleep.
