PCOS (PMOS) and Fatigue: Why You're Always Tired

Medically reviewed by Puja Vyas, Lead Clinical Pharmacist.

‍

For most women afflicted with the PMOS, the most common symptom is a constant sense of fatigue. Unfortunately, it is often overlooked as a symptom of the disease, or just accepted as the cost of a busy life.

Are you always tired? Do you not seem to have slept a wink when you wake after a good night's rest ? It might be you if you suffer from PMOS (formerly PCOS). It's not in your head and you're not lazy.

The problem is that there are several reasons for the PMOS induced fatigue. Once you have identified the cause of your fatigue there is often something you can do about it.

Let's look at why PMOS is possibly making you tired and what's likely happening in your body, what you might want to discuss with your GP and what can be done to improve things.

‍

Key Takeaways

• Fatigue is one of the most commonly reported experiences in PMOS, but research is still limited. It usually has several contributors rather than one single cause.
• Sleep disruption, low mood, insulin resistance, low iron, thyroid problems and certain medicines can all play a role and are worth investigating.
• See a GP if you have been persistently tired for several weeks without a clear reason, or if tiredness comes with other symptoms.
•  Some causes such as low iron, an underactive thyroid or low vitamin B12, are very treatable once found.
• Do not start supplements without checking your levels first. The evidence for most fatigue supplements is limited, and some are unnecessary at normal levels. 

‍

Is Fatigue Really a Symptom of PMOS?

What the Research Shows

Yes! Research-wise, a link exists between PMOS and fatigue.

There was a small study of 52 women with PCOS, where the researchers found fatigue linked to anxiety, depression, and insomnia (PMC12306717). Recognition of the increased sleep disturbance in women with PCOS was also made in the 2023 international evidence-based PCOS guideline.

Other research has also discovered that there is a reduction in energy levels, a decrease in quality of life and increased daytime sleepiness in women with PCOS compared to women without the condition.

So, does that mean we know how many women with PMOS are fatigued? Not exactly. As of now, no one has an exact number. Any of the numbers you come across can be from population surveys or studies, so you need to be aware of that.

The reality is that a lot of women suffering from PMOS experience fatigue and this is an issue that is really overlooked. Then you'll also read what others are saying about your experiences, and you'll understand how difficult it can be.

On a Reddit community called r/PCOS have said that they are exhausted all day every day. One woman said that she had gotten used to being exhausted and just thought that was normal. It wasn't until she was treated that she realized how much it had impacted her.

One said that she felt "awful" because of the brain fog and tiredness from PCOS. She also explained how upset she was when people without it told her to 'just get some sleep'.

Another woman shared that she could not get through her day without an energy drink and a cup of coffee. She was worried about the effect the sugar in them might be having on her insulin resistance.

Spot the issue? You are already exhausted, and now you are asking yourself if the things that are getting you through the day may be fueling something else.

What Does PCOS Fatigue Actually Feel Like?

The NHS describes fatigue as a tiredness, which does not improve with rest. This is not a 'normal' tiredness following a long day and usually improves after a good night’s sleep.

And what would PMOS fatigue in the field look like then?

You might see:

• Hours of sleep with no energy when waking up.
• Difficulty concentrating or remembering (brain fog).
• No motivation and energy to do anything.
• Have difficulty getting through normal daily activities.
• Feel lethargic throughout the day even when getting a good night's rest.

And it can be extreme for some women.

Imagine you wake up feeling sleep deprived after having 10-14 hours of sleep. Or, you're at work at your desk and you're fighting to keep yourself awake, and all of your colleagues are convinced that you're doing just great.

Many women with PCOS will bring this up as well. If this kind of fatigue is happening constantly, not just once in a while, then there is big trouble. It shouldn't be one of those things you accept as normal.

‍

Why Are You Always Tired With PMOS?

There's one thing you need to know about PMOS. There is never one cause. All of this can happen at the same time and still be affecting energy. Here are some of the ones, which happen to us all most often.

Poor or Interrupted Sleep

Even if you spend more than 8 hours in bed, are you getting a good night's sleep?

PCOS is also linked to higher rates of sleep problems compared to women without PCOS. From the 2023 International PCOS Guideline: Sleep disorders are increased in women with PCOS.

A 2025 meta-analysis in Frontiers in Endocrinology found that 37% of women with PCOS had sleep apnoea compared to 6% of women without PCOS having sleep apnoea. That's nearly six times the amount!

So what is sleep apnoea exactly?

A condition where there is a periodic cessation of breathing, or a pause, during sleep, that can be repeated over and over. During sleep, they can be interrupted by hundreds of small arousals or causes of waking.

The kicker? You might not have even realized you were awake.

Yet, your sleep is disruptive throughout the night, and you wake up exhausted despite having had eight hours of sleep.

Though, sleep apnoea is just one of a number of things that can affect how much rest you get: like insomnia, difficulty sleeping and nights of disrupted sleep.

If you're sleeping 8 hours, but waking up tired? Then it might be worth a look. We've covered this in great detail in our article on PCOS, sleep apnoea and poor sleep.

Low Mood, Anxiety and Stress

Did you realise that you may become more exhausted when you are feeling anxious, stressed, or having a tough time? That's for a good reason.

Women with PCOS are five times more likely to experience anxiety and depression. Both of these affect energy and motivation.

Do you remember that small pilot study we mentioned earlier? Well, it found that anxiety and depression were the two things that most likely influenced the degree to which women with PCOS felt exhausted.

Stress, of course, is another factor. You're chronically stressed out. High levels of cortisol can also disrupt your sleep patterns and, and because of this, worsen physical fatigue. If you have anxiety and low mood alongside PMOS then don't think these are two completely separate things. They can be quite connected.

We discussed more on this in our article about PCOS and mental health.

Insulin Resistance and Energy Dips

A common symptom for women who have PMOS is that your body's cells become less sensitive to insulin. So, what happens?

Your blood sugar levels increase following a meal, mainly if that meal includes any food(s) that cause your blood sugar to spike. This is your body releasing more insulin to lower it. Sometimes your blood sugar will go that low again, and you'll become very tired. Have you noticed that after you eat you feel so very sleepy as if someone turned off the gas?

One of the frequent complaints of women is "fatigue due to PCOS after eating".

A small amount of research has been conducted to find the link between insulin resistance and persistent fatigue related to PCOS. Though, such energy crashes after eating the meal are a common event.

You may want to read our article on PCOS, insulin resistance and metformin for more details. 

Heavy or Irregular Periods and Low Iron

Next on the list: Your Iron!

Iron deficiency anemia is quite common in women who are menstruating. Heavy periods are a leading cause of this.

Why is this important?

Iron helps your body make haemoglobin, which carries oxygen to all parts of your body. If you don't have enough iron in your body, you can become anaemic. This can cause you to become tired, weak, and more sleepy and take away your concentration.

It is that these symptoms can be far too similar to the ones linked with PMOS fatigue. So, it might be hard to identify the root causes of your fatigue without taking a blood test. This woman in r/PCOS said she feels like a "zombie" at ferritin levels below 50, and doesn't sleep well until her iron levels are improved.

If you have heavy periods or periods that go on a long time, ask your GP to check your iron levels. Read about PCOS periods and period pain to find out more about irregular periods and what to discuss with your doctor.

Thyroid Problems

Women with PCOS are at higher risk of a thyroid problem than women who don't have PCOS. A 2025 systematic review and meta-analysis of women with PCOS found that about 20% of women had subclinical hypothyroidism.

The thyroid is a butterfly shaped gland located in your neck that helps to regulate the energy used by your body. If the gland in the neck fails to produce adequate quantities of this hormone, there is an underactive thyroid (hypothyroidism).

The most common symptom? Tired all the time.

The NHS also states that other symptoms are gaining more weight than normal, feelings of depression and feeling cold more often than normal. Good news if you do have a thyroid problem - it can be diagnosed in a blood test and is simple to treat. So if it's been a while since you last had your thyroid checked, that's something to bring up when you next see your GP.

Medicines and Other Causes

Perhaps there's a couple of additional items that might be causing you to be tired. Let's have a look.

Metformin and Vitamin B12

Here's what you need to be aware of if you are using metformin to treat PMOS.

The MHRA has warned that long-term metformin use can lower vitamin B12 levels. In fact, this is a common side effect, affecting up to 1 in 10 people taking the medicine long-term.

Is this relevant to you? Feeling exhausted - low vitamin B12 can cause fatigue.

For longer-term users of metformin, MHRA recommends that vitamin B12 levels be checked regularly, where symptoms exist. If you are taking metformin and you are more tired than usual, talk to your doctor about checking your B12.

Do not stop taking metformin without consulting your doctor. It is common for women with PMOS to be on this medication so if you wish to change your medication please speak to your consultant.

More information is available in the article about PCOS, insulin resistance, and metformin.

Over-Exercising and Eating Too Little

Getting more exercise and eating well is a great way to have a healthy life with PMOS. But there is a limit where you push over a point that can do more harm than good. If you're exercising at high intensity and you're already out of energy from fatigue or you aren't giving your body enough to be able to sustain you.

You don't need to overexert yourself to move more. If you already have fatigue, you should take gentle and regular exercise rather than strenuous exercise. We have put together some exercise guidelines to discover what might work for your body rather than against it.

‍

Tiredness Around Your Cycle

Do you have a time leading up to your period when you are very tired? This might be connected with PMS. Having low energy is another PMS symptom that happens before a period.

If you generally feel tired during the week or two just before your period and then experience relief, this may also be related to your menstrual cycle. Well, that's not quite the fatigue we mean.

If you want to know the difference, check out our article on PCOS vs PMS and PMDD.

Though, if you are tired most of the day after you have reached this stage of your cycle, it may be worth talking to your GP about this and investigating all the other possible causes.

‍

How to Find Out What's Behind Your Fatigue

Since we've gone through the various possible causes, we will cover what you are able to do! The first thing you should do is to identify the root cause of your tiredness. There is a lot you can do for yourself before getting to the GP, but start with knowing what to tell your GP and when.

When Should You See a GP?

The NHS says that if you've been tired for a few weeks or so and have no idea why, you should see your GP.

If you have fatigue, which might be accompanied by other symptoms as well, you need to go to the doctor, for:

• Unexplained weight changes.
• Does your mood change?
• Feeling cold all the time.
• Struggling to breathe when asleep.

NICE guidelines for tiredness and fatigue in adults recommend that for persistent tiredness where no obvious cause can be found, the person should be assessed.

So just stop it right now mainly if this is bothering your daily life due to the fatigue you are experiencing.

What Should You Say at Your Appointment?

If you find it hard to describe how fatigued you are, it may just be that you say to your GP, "I'm so tired all the time" and there just isn't anything else to say. With a little bit of prep, that chat can be much more productive.

Here's what we recommend.

Describe Your Pattern

Start by describing your fatigue.

Is it present constantly or occasionally? Are you happier after getting to sleep or do you awake just as exhausted? For how much time have you had this problem? Does it interfere with your responsibilities, interactions with colleagues, relationships, or various activities?

A good old two-month energy diary can really do the job.

Don't overthink it. Just jot down:

• Duration of sleep and quality of sleep.
• How energised you are throughout the day.
• What and when you consumed.
• Mood and stress.
• Which days you had your period.

This allows you and your doctor a much better understanding of what is actually going on rather than just by saying you're tired all the time.

Mention Your Periods and Medicines

Be sure to add your times also.

Are they really big or deep? Are they uneven? Your GP may find this information useful in considering the possibility that your tiredness could be due to iron deficiency.

If you are also taking the pill called metformin, let your GP know. They may wish to do a blood test to see what your vitamin B12 levels are.

If someone's told you snore, or if you sleep for long hours but still find yourself yawning upon awakening, tell them that too. It might be worth checking for sleep apnoea.

Ask About Tests

It isn't necessary to make wild assumptions about what is wrong. Still, asking your GP for any tests that might help reveal the cause of your fatigue is entirely appropriate.

Your GP may take your blood tests to test for these:

• Anaemia.
• Diabetes.
• Thyroid problems.

Vitamin B12, vitamin D and ferritin testing might also be worth considering.

Ferritin is in particular important as it gives an indication of the levels of iron in the body. Ferritin can be low even when the haemoglobin is not. The appropriate tests that should be done are a clinical decision given your symptoms and history, which your GP will establish.

And remember, getting normal test results doesn't mean your appointment was pointless. Ruling out possible causes is also an important part of finding answers.

‍

What Can Help PMOS Fatigue?

You've started to look into potential causes - but what can you do to regain your energy?

There is no one correct answer to this, as it depends on the root cause of your tiredness. Here are a few tips on what does.

Treat the Cause First

This is the most important one to keep in mind. Think about low iron, underactive thyroid, low B12 or sleep apnoea. How can I reduce it? See about managing these problems, and your sleep.

All of these conditions are treatable. For lots of women, the actual cause is as such a factor for their own energy level. It can sometimes be a lot more effective compared to the lifestyle modifications.

And here's why you need to be checked. Don't waste months trying to lose weight on different programs, cleanses, and workouts when you need to find out what the real issue is.

Steady Energy: Sleep, Movement and Stress

Once the underlying condition has been dealt with (or in the meantime) you can do some easy things to keep your energy up.

shall we begin with sleep ?

Aim to go to bed and wake up at the same time every day, even at weekends. If you have a consistent schedule, your body can keep a healthy sleep-wake rhythm.

Next, think about movement.

You need not exercise for extended hours and hours. Gentle exercise regularly is an effective means to develop some consistency without getting exhausted. If you are trying to find out how to work with PCOS, our overview of the very best exercises for PCOS will definitely give you some concepts.

And finally, but really - don't forget about your mental health. If anxiety and low mood are affecting your energy, support is available. CBT and other talking therapy support is free on the NHS platform.

Oh no, it's not just your headache, it's that you are tired! Your mental health is as important as your physical health.

Eating Regularly

Let's talk about food!

It might seem like a good idea to try to shed weight by not eating at all or very little, but that can actually make you more tired. Eating regularly helps maintain the blood sugar level, as well as possibly reducing the energy dip in the hours following a large blood sugar shift.

It's not about how much you eat. It's about nourishing the body. If you are uncertain on how to get started with your diet, then our PCOS diet guide can provide you with information on what kind of foods and eating habits may benefit you for PMOS.

What About Supplements?

If you search high and low on the internet for PCOS fatigue supplements, you may be thinking whether or not there is a supplement you can take to get your energy back. We can see your reasoning. When you're that exhausted and you're willing to do anything just to feel better, it's tempting to start to try anything.

The issue here is that there really is very little evidence in the research that supports that most supplements provide specific benefits in reducing fatigue in women with PCOS. The key is to see whether you are taking in too few of any foods.

The potential causes of tiredness, iron, vitamin D and vitamin B12, should be given to us in supplement form if levels are low. Yet using dietary supplements without first testing your levels is not always helpful. Sometimes it can even be counter productive. Be sure to check out items that fall under the category of "adrenal support" supplements as well. We would recommend exercising caution in these.

"Adrenal fatigue" is not a medical diagnosis. There is no scientific literature to support the concept of adrenal fatigue, and a 2016 systematic review in BMC Endocrine Disorders found no scientific evidence.

You're exhausted. Don't waste your money on "adrenal fatigue" supplements; instead, investigate the genuine underlying reasons listed above. A list of what supplements appear to have some evidence behind them, and what the evidence actually says, is included with the PCOS diet plan.

‍

Want to Understand Your Hormones? Try the PMOS Screening Kit

If you think you might have PMOS but haven't yet been diagnosed then the first step is to learn more about your hormones. Our PMOS Screening Kit allows you to screen all 19 hormones/metabolic markers, right from your home.

This encompasses thyroid function and other key markers of insulin resistance. Review by GP included in results. Please remember, the kit does not identify the cause of tiredness. Still, if you constantly feel tired and this is negatively impacting your usual routine, please book an appointment with your GP.

If you're still on the fence about whether or not you have PMOS, the screening kit can be a helpful aid in painting a clearer picture of your hormones and bringing along to your appointment.

‍

💜 Bestie Tip

If you have been told your exhaustion is "just PCOS" or "just stress" — please hear this: constant tiredness is not something you have to accept as normal. You deserve to know what is actually behind it. Write your symptoms down, book that GP appointment, and ask for the tests. You are not being dramatic. You are advocating for yourself, and that is exactly the right thing to do. 

‍

Frequently Asked Questions

Does PCOS cause fatigue?

Fatigue is not a symptom of PCOS, but it is a common side effect of the disorder. Often means many energy problems such as: insomnia, insulin sensitivity, mood swings, menstruation problems. If you notice a few of these together it's also a sign that you might be more exhausted than you might think.

Can PCOS cause extreme fatigue?

Yes, some women with PCOS experience very severe fatigue. This can happen if a lot is happening in your body. They all can be your underlying cause for poor sleep, low iron, a low mood, and blood sugar changes. One of these may become a source of fatigue. 

What does PCOS fatigue feel like?

Imagine a fatigue, which doesn't disappear after a great night of sleep. Waking up, you may be tired, unfocused, lack motivation and be dragging yourself through your day. Many women say it is not an occasional thing for them, but part of their normal life. It is also possible that you might feel some of these brain fog symptoms.

How do I get rid of PCOS fatigue?

Speak to your GP and ask them to test your iron level (ferritin included), thyroid level, B12 and vitamin D. Find out if you think you have sleep apnoea and if you need a referral to have more tests. Meanwhile, get a regular sleep pattern, eat daily at the same time and engage in some form of light physical activity on a daily basis.

Is PCOS fatigue the same as adrenal fatigue?

No, they are not identical. If so, there is no such thing as "adrenal fatigue" in the medical language. In 2016, the investigators of BMC Endocrine Disorders examined the evidence to date and didn't find it. Fatigue is yet real. But, rather than reaching for something marketed as a solution for "adrenal support" it might be wise to look back at the possible underlying culprits we've just listed, like disturbances in sleep, the potential lack of iron or the possibility of thyroid or insulin resistance.

Can metformin cause tiredness?

The most common side effect of long-term use of metformin is low vitamin B12 levels, affecting as many as 1 in 10 patients, reports the MHRA. Symptoms can include severe fatigue. When you are on metformin and if you experience unusual exhaustion, then check with your GP whether you should have your B12 level tested.

Yet, don't just stop any medication without first talking to your doctor. It is not just a matter of stopping a treatment you might need, but more of a matter of reviewing and controlling your B12 levels.

When should I see a GP about tiredness?

If your fatigue has been going on for a few weeks and you don't know why, the NHS recommends that you see your GP. Additional reasons to seek doctors' advice are if the fatigue is present with unexplainable weight loss, weight gain, mood swings, cold sensation all the time and if you wake up gasping for air.

‍

The Bottom Line

If you take one thing away from this article, let it be this: It's not something you have to suffer through all the time.

There are lots of reasons that could be causing you to be tired, including low iron, a problem with your thyroid, not getting enough sleep, feeling low, or not enough vitamin B12.

Most of them are treatable after diagnosis.

So, your first step is to become familiar with your symptoms and talk with your GP about this and get tested. You should have a reasonable amount of energy and not feel tired all day long. You deserve better than this.

Click here to read all about PMOS on our Complete Guide to PCOS and PMOS.

If you're still working towards a diagnosis, our PMOS Screening Kit can tell you a lot more about your hormones.

‍

Not sure what is behind your tiredness?

If you have not yet been diagnosed with PMOS, the PMOS Screening Kit checks up to 19 hormone and metabolic markers from home, with a GP-led review. It will not diagnose the cause of your fatigue, but it can be a useful step towards understanding your hormones. Find out more about the PMOS Screening Kit. 

‍

PINK FRIDAY OFFER

PMOS Screening Kit. Was £149, now £99.

‍

References

●      International evidence-based guideline for the assessment and management of PCOS 2023 (PMC10505534)

●      Psychological Distress and Fatigue in PCOS: A Pilot Study (52 women, cross-sectional; PMC12306717)

●      Obstructive sleep apnea syndrome in PCOS: systematic review and meta-analysis. Frontiers in Endocrinology, 2025

●      Prevalence of subclinical hypothyroidism in PCOS: systematic review and meta-analysis (2025)

●      NHS – Tiredness and fatigue

●      NHS – Iron deficiency anaemia

●      NHS – Underactive thyroid (hypothyroidism)

●      MHRA – Metformin and reduced vitamin B12 levels: new advice for monitoring

●      NICE CKS – Tiredness/fatigue in adults

●      Adrenal fatigue does not exist: a systematic review. BMC Endocrine Disorders, 2016 (PMC4997656)

‍