Why Does PMS Make You Sleepy? Period Fatigue Can Have Many Causes

Among the many common, unpleasant symptoms you might have in the days leading up to your period (you know 'em: your garden variety bloating, headaches, moodiness, and general aches and pains), period fatigue can be one that makes functioning throughout the day anywhere from mildly difficult to downright impossible.

Despite feeling like an absolute curse from whatever PMS gods are out there, premenstrual fatigue is actually quite common, as two OB-GYNs explain. Monica Grover, OB-GYN and Chief Medical Officer at VSPOT, tells Scary Mommy, "It is very common to feel tired or fatigued before your period. However, the degree of having a dip in energy levels may vary and can be significant" for certain period-havers — more on that in a sec.

What Causes Period Fatigue?

As for what causes pre-period fatigue, you can blame it on your hormones. Along with other PMS symptoms — all of which can cause or exacerbate that horrendous "simply can't stay awake" feeling — Kecia Gaither, an OB/GYN and director of perinatal services at NYC Health + Hospitals/Lincoln, notes that it's all due to the hormonal fluctuations you experience at this point in your menstrual cycle.

Grover says that "estrogen usually acts as a stimulant, but its levels significantly drop after you ovulate, depriving you of its energy while serotonin levels decrease. Once these serotonin levels decrease, there is now a significant dip in energy levels," which you can officially chalk up to premenstrual syndrome (aka PMS). Gaither adds that fluctuations in serotonin (the brain's "feel-good" hormone) contribute, affecting your mood. A nice little cherry on top, right?

Heavy bleeding can also be the root of your fatigue. Every menstruating person has a different flow, and if yours is especially heavy, it can take more energy out of you than those with lighter periods. You probably have a heavy flow if you go through sanitary napkins quickly, have large blood clots, or menstruate for more than a week. If this is the case, check in with your doctor to better manage your period.

How Long Does It Last?

Gaither says that the worst of the fatigue will typically subside once you start your period (and definitely by the end of it). Still, Grover notes that every person is different, adding, "Sometimes, fatigue will increase or decrease depending on hormonal changes. The fatigue should ideally subside upon menstrual onset, but in some cases, it can continue."

Although most people with periods do experience PMS symptoms to some degree (lucky us!), according to Grover, premenstrual dysphoric disorder (PMDD) can be more significant, as it can start 7-10 days prior to menstrual onset and can be very debilitating for those who are experiencing it. Look for symptoms such as "extreme moodiness, including crying spells without a significant cause, anxiety, anger, a lack of interest in things they would normally enjoy, or feeling out of control."

How Do You Deal With Period Fatigue?

If pre-period fatigue — or any kind of fatigue, really — interferes with your daily life, both experts recommend checking in with your doctor. "Doctors can run blood tests to see if there is another underlying cause to your extreme exhaustion. Additionally, if there is a significant pattern or if it becomes a significant disturbance in day-to-day activities, be sure to consult with your doctor," Grover suggests.

Several potential underlying conditions could be causing your extreme symptoms, says Grover. These may include:

• Anemia. For people with heavy periods, "You lose a lot of blood, which could lead to an iron deficiency in your red blood cells. This can most commonly be due to uterine fibroids."
• Endometriosis can cause intense pelvic pain, leading to fatigue.
• Hormonal imbalances such as polycystic ovarian syndrome (PCOS) and chronic fatigue syndrome often result in ongoing fatigue.
• Thyroid disorders can sap your energy, too. They occur when your thyroid doesn't produce enough (called hypothyroidism) or produces too much (hyperthyroidism).
• Mood disorders such as major depressive disorder and anxiety commonly involve fatigue. Sleep inertia, or a transitional state between sleep and wakefulness, is an often-cited culprit.
• Certain nutrient deficiencies outside of iron, such as B-vitamin or magnesium, can lead to lethargy.

Along with checking in with your doctor, there are some expert-approved ways to help manage your pre-period sleepiness. Both experts recommend a well-balanced diet, with Gaither noting that foods and drinks with high sugar content or alcohol can cause spikes in blood sugar followed by extreme lows that can contribute to fatigue. She also recommends drinking plenty of water, as "dehydration can make you tired, making PMS symptoms worse."

Both doctors recommend moderate exercise (a walk or a gentle jog) if you can muster it, with Gaither adding that movement can help boost energy levels. But don't feel bad if you're skipping that CrossFit class or intense cycling session — you don't want to further fatigue yourself.

You'll also want to keep your bedroom cool at night, since pre-period night sweats can put a (ahem) damper on a quality night's sleep.

Grover also notes that antidepressants like Zoloft can help those with severe PMDD symptoms. There's absolutely no shame in caring for yourself any way you need to, especially in the lead-up to your period.

A few other things that can help you get through your period fatigue is creating a comfortable space for you to sleep. Keep in mind that a person's body temperature increases before their period, which can affect their quality of sleep. So keep your bedroom cooler for a restful night, which will help you feel less fatigued throughout the day.