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Why Am I So Tired on My Period? Keeping Sleep Debt Low Helps

Periods are never fun, especially when they come with extreme fatigue. But focusing on sleep debt, sleep hygiene, and your circadian rhythm can help.
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Jeff Kahn, M.S., Rise Science Co-Founder
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Woman sitting up in bed having a hard time sleeping maybe because she is on her period

No, you’re not imagining it. Your sleep really does suffer when you’re on your period. Along with mood swings, cramps, and carb cravings, your period also makes it harder to sleep. Period-related pain might keep us up and hormonal changes may make falling and staying asleep all night more tricky. Research shows women report more sleep disturbances during their period, and the week leading up to it, than any other time of the month. What’s more, your sleep can be disrupted around ovulation, and tiredness is also a symptom of PMS, or premenstrual syndrome, which happens in the weeks leading up to and sometimes during your period.

In this blog post, we’ll cover what’s causing all this tiredness and what you can do about it. We’ll explain how keeping sleep debt low, maintaining good sleep hygiene, and aligning with your circadian rhythm can help to increase your energy while on your period — and every other day of the month, too.  

What Causes Period Fatigue?

There can be a few culprits making you feel extra lethargic on your period. 


In short, hormonal changes while on your period and fluctuations throughout your monthly cycle may wreak havoc with the hormones responsible for making you feel sleepy and alert and with your body temperature, which can disrupt sleep. Here’s what’s happening: 

Just before your period, levels of the hormones progesterone and estrogen are at the lowest they’ll be in your entire roughly 28-day cycle. These low levels prevent melatonin, the sleep-inducing hormone, from being released effectively. And without enough melatonin, you may find it harder to fall and stay asleep. 

As progesterone and estrogen levels rise again around day seven in your cycle, melatonin production returns to normal. But it’s impacted yet again around day 14 during ovulation, when estrogen levels are at their highest, which stimulates the nervous systems and makes us feel more awake. By day 21, sleep may improve again, but it’s impacted once more by our hormones come day 28, the end of your monthly cycle, when progesterone and estrogen levels fall again. However, studies looking at how the menstrual cycle impacts melatonin are conflicting, highlighting the need for much more research to be done in this area. 

Studies on how the menstrual cycle affects the stress hormone cortisol are also contradictory, but it may reduce how much is made. Cortisol peaks in the morning and is responsible for making us feel awake and alert.

Research also shows women in the luteal phase of the menstrual cycle have higher body temperatures, levels of alertness, and cognitive performance compared to those in the follicular phase — and menstruation happens as part of this phase. 

​​Unfortunately, things aren’t much better for women taking birth control pills. These contraceptives suppress your reproductive hormones, preventing ovulation, and therefore pregnancy. However, they also interfere with your body temperature, melatonin production, and — surprise, surprise— your sleep. Studies have found women taking oral contraceptives have higher levels of melatonin at night compared to those not on contraceptives. However, they also experienced a higher body temperature — which makes it harder to drift off — less slow wave sleep, also known as deep sleep, and less rapid-eye movement (REM) sleep. We look at whether birth control can make you tired here.

Medical Issues

Tiredness on your period may also be due to heavy bleeding as the blood loss can cause an iron deficiency anemia. If you have particularly heavy periods, it may be worth speaking with a healthcare professional to see if you have low iron levels and whether supplements could help.

Period-related tiredness may also be a symptom of PMDD, or premenstrual dysphoric disorder, a more extreme version of PMS. Again, speaking with a healthcare expert is your best bet here to discuss treatment options.

Period-Related Pain 

Pain is another reason you may feel menstrual fatigue. Many of us experience abdominal cramps, lower-back pain, headaches, or uncomfortable bloating — all of which make it harder to fall asleep and may even wake us up in the night. 

High Sleep Debt 

Sleep debt is the amount of sleep you owe your body over the last 14 nights. For example, if your sleep need — the genetically determined amount of sleep you need each night — is 8 hours 30 minutes, but you’ve only been getting 7 hours of sleep each night, you’ll have a large amount of sleep debt. Lack of sleep is one of the main reasons why you’re so tired, whether you’re on your period or not. However, you may lose some extra sleep during your period, increasing the amount of sleep debt you have, and therefore making you feel more tired during the day. We cover how much sleep women need here.

Circadian Misalignment 

The circadian rhythm is your internal body clock, the roughly 24-hour cycle that controls when you feel energized and tired. It’s affected by everything from light exposure, meal times, and – you guessed it — your menstrual cycle. At least that’s what some studies suggest. 

Research shows hormonal changes during your monthly cycle may directly change your circadian rhythm, and this may in turn impact your mood. However, more research still needs to be done. It may work the other way, too. Disruptions in your circadian rhythm may lead to changes in your menstrual cycle. For example, female shift workers are more likely to experience irregular periods and longer menstrual cycles compared to non-shift workers. And working shifts can even increase period pain. 

But even if your period doesn’t impact your circadian rhythm, being out of sync with your body clock will make you feel tired during the day. Here’s why you may be out of sync: 

  • You’re not thinking about your chronotype: Maybe you’re a night owl, but have to wake up early for work.
  • You have social jetlag: You stay up late and sleep in on the weekends, only to return to an earlier schedule come Monday. 
  • You’re a shift worker: You might have to be awake and working through the night when your body really doesn’t want to be. And, even worse, your work hours, and therefore sleep schedule, might change regularly. 

Sleep disturbances during your period may also lead you to be asleep and awake at different times than usual, making you out of sync with your body clock. 

How to Feel Less Tired on Your Period 

Unfortunately, we can’t control our hormones, but there are a few other lifestyle tweaks you can make to reduce the amount of tiredness you feel while on your period.  

Reduce Sleep Debt 

RISE app showing how much sleep debt you have
The RISE app will tell you how much sleep debt you have and keep track as you pay it back.

By keeping your sleep debt low — we recommend under 5 hours — you’ll give yourself the highest chance of feeling and performing your best during the day. However, sleep disruptions from hormonal fluctuations and period pain can make it hard to meet your sleep need while on your period. Therefore, try to lower your sleep debt before you start your period. 

In the week leading up to your period, pay back some sleep debt by taking naps in your afternoon dip in energy (the RISE app can tell you when this is), going to sleep a little earlier, or sleeping in a little later. You can also focus on sleep hygiene (more on that soon) to reduce the amount of time it takes to fall asleep and how much you wake up during the night. By starting your period with low sleep debt, you’ll ensure that even if you do build up some sleep deprivation over the next few days, your overall number will stay low, meaning you’ll feel much better each day. 

RISE can calculate your individual sleep need. The average sleep need is 8 hours 10 minutes, plus or minus 44 minutes or so, but 13.5% of the population may need 9 hours or more sleep a night. The app can then determine how much sleep debt you have, and keep track of it as you pay it back. 

Align With Your Circadian Rhythm 

Being out of sync with your circadian rhythm can make you feel tired at any time of the month, but especially when you’re on your period and possibly getting less sleep than usual.

Here’s how to stay in sync: 

  • Keep a consistent sleep schedule: As much as possible, try to go to sleep and wake up at the same time each night, even on weekends. This will regulate your circadian rhythm and help you fall asleep easier, therefore getting more sleep each night.
  • Go to sleep and wake up at the right time for you: There are times when your body naturally wants to go to sleep and wake up, and they’re different for everyone. Align with these times to have an easier time falling asleep (and therefore get more sleep) and feel more alert during the day. If work and personal commitments get in the way, consider resetting your sleep schedule.  
  • Schedule your day with your energy peaks and dips: We all experience natural peaks and dips in energy throughout the day — there’s usually a natural dip in energy mid afternoon and another before bed. By knowing this afternoon dip is coming, and checking the timing of it with a tool like RISE, you can schedule low-energy tasks (like emails and admin) for these times. Instead of fighting the tiredness, work with it, and save more difficult and demanding tasks for your natural peaks in energy. 

Practice Good Sleep Hygiene

RISE app screenshot telling you what times to limit caffeine
The RISE app can tell you when to stop sleep-disrupting behaviors each day depending on your circadian rhythm.

Sleep hygiene is a set of daily behaviors you can do to help you fall asleep easier and quicker, keeping sleep debt low in a time when it’s so easy to lose out on sleep. Here’s what you can do: 

  • Get natural light first thing: This triggers cortisol production, making you feel awake, and it resets your circadian rhythm for the day. 
  • Avoid light in the evenings: It needs to be dim for melatonin to be produced, so turn down the lights and put on blue light blocking glasses about 90 minutes before bed. 
  • Keep your bedroom dark, quiet, and cool: Use blackout curtains, an eye mask, and earplugs to avoid light and noise disrupting sleep. Aim to keep your bedroom at 65 to 68 degrees Fahrenheit — this is important all month long but especially around your period when your body temperature is elevated.  
  • Avoid caffeine, alcohol, physical activity, and meals too close to bedtime: All four can disrupt sleep, which is not something you want when sleep may already be disrupted by your period. RISE can tell you the right time to stop these things each day based on your circadian rhythm.

Manage Period Pain

While there’s not much you can do about the hormones that impact your energy levels, there are treatment options to address the pain that comes with being on your period. If period pain is disrupting your sleep and making you feel tired the next day, try holding a hot water bottle to painful areas and taking magnesium supplements. Studies show taking a daily magnesium supplement may help treat and even prevent cramps and menstrual migraines, and they could also reduce bloating. Taking 1,200 mg of calcium a day may also help to reduce PMS symptoms.

Keeping your sleep debt low can also help with pain management. As much as pain can disrupt sleep, sleep deprivation can also make pain worse, creating a vicious cycle. So, by lowering sleep debt before the onset of period pain (by getting more sleep in the week leading up to it), you may actually be able to reduce the amount of pain you feel just by being less sleep deprived.   

Have More Energy Each Day, Even on Your Period 

Unfortunately, there really isn’t a lot of research into why women experience tiredness during their periods. At RISE, we’d like to at least share what science does know about this phenomenon and the things you can do about it. 

Fluctuating hormone levels and period-related pain may be the main culprits, however, high sleep debt and circadian misalignment may also play a role in why you’re feeling so tired. The RISE app can help you keep your sleep debt low and sync up with your circadian rhythm. Do these things both while on your period and throughout the rest of the month to feel less tired each and every day. 

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