Stress is real, but thyroid, iron, B12, blood sugar, sleep apnea, and hormones can look exactly the same. Here’s what to check.
You’ve been exhausted for months. Sleep is a mess. Your mood is short. Your focus is shot, and your body just doesn’t feel like yours.
So you finally bring it up, and the answer is, “It’s probably just stress.”
Maybe that’s true. Stress is real, and I’m not going to wave it away. But if you walked out of that conversation still feeling like something else is going on, I want you to hear this:
“Just stress” is sometimes part of the story. It’s rarely the whole story.
This post covers what stress really does to your body, the other conditions that can look exactly like it, and what I look at from a functional medicine and pharmacist perspective. It’s educational and isn’t a substitute for care from your own healthcare team. Numbers in brackets point to the references at the end.
When you’re under pressure, your body releases stress hormones, including cortisol and adrenaline. That response is useful in short bursts. But when it stays on for weeks or months, it can wear on your body, affecting sleep, mood, blood pressure, blood sugar, and immune function.[1] (More in my post on how stress affects your body.)
Sleep and stress also feed each other. After a night of short sleep, cortisol runs higher the next evening,[2] which can make it harder to fall asleep the next night. It’s a loop, and it can leave you feeling wired and exhausted at the same time.
So yes, stress deserves attention. The problem isn’t taking it seriously. The problem is when it becomes the only explanation, and nobody checks anything else.
The symptoms of stress are also the symptoms of many other things:
And when a cause is missed, the stress you’re feeling can get worse, because feeling unwell is stressful in itself. Here’s what I look for.
These are the conditions I most often see brushed off as stress. None of them rules stress out. Each is worth checking.
Too slow or too fast can both feel like stress.
An underactive thyroid can cause fatigue, low mood, brain fog, weight gain, and feeling cold.[3] An overactive thyroid can cause anxiety, a racing heart, trouble sleeping, and weight loss.[4] Both are easy to mistake for stress, and both are found with a blood test.
Ask for more than TSH alone: free T3, free T4, and thyroid antibodies can add useful information. (See why you can still feel hypothyroid with a normal TSH, and if you’re already on treatment, why thyroid medication works better for some people than others.)
Low iron can drain you even without anemia.
Low iron, even without anemia, is a common and often overlooked cause of fatigue. In a randomized trial of menstruating women with unexplained fatigue and low ferritin (stored iron) but no anemia, iron supplementation reduced fatigue compared with placebo.[5]
Ask for your actual ferritin number, not just “normal.” And talk with your provider before starting iron, because too much is harmful. More on the hidden causes of anemia.
Common, quiet, and easy to check.
Low B12 can cause fatigue, brain fog, and mood changes, and it can also affect your nerves.[6] It’s more common with acid-reducing medicines, metformin, and some digestive conditions.
Vitamin D is worth discussing if you’re at higher risk, such as with limited sun, darker skin, or certain gut or autoimmune conditions. Current guidelines don’t advise routine testing for everyone.[7] I cover that in my complete guide to vitamin D.
The afternoon crash isn’t always about your schedule.
Blood sugar swings can contribute to shakiness, hunger, irritability, fatigue, and trouble sleeping. Fasting glucose and A1c are the standard screens.[8]
I also look at fasting insulin, because insulin can start rising years before glucose does. (See how insulin resistance develops silently.)
Tired no matter how many hours you sleep.
Sleep apnea causes repeated pauses in breathing at night, so sleep never fully restores you.[9] It’s not just loud snoring, and it’s not just in men.
Women more often describe insomnia, morning headaches, low mood, and fatigue rather than the classic symptoms, so it gets missed.[10] If that sounds like you, ask about a sleep apnea screen. (See what happens to your hormones when you don’t sleep.)
This is a big one.
In perimenopause, swings in estrogen and progesterone can cause sleep disruption, anxiety, irritability, brain fog, and fatigue, often before hot flashes begin.[11] More in my posts on perimenopause symptoms that get missed and anxiety or perimenopause.
In men, low testosterone can cause fatigue, low drive, and low mood, and it’s diagnosed with symptoms plus consistently low morning levels.[12] (See low testosterone and lost drive in men.)
As a pharmacist, I always check this layer.
Some medicines can cause fatigue, insomnia, or anxiety. Caffeine, alcohol, certain cold medicines, and some supplements can too.
If your symptoms started around the time you started or changed something, mention it. Timing is one of the most useful clues there is.
If you’re not sure whether your symptoms point to hormones, a good first step is understanding your pattern. My free Hormone Type Assessment is a short quiz that helps you see whether your symptoms point toward one of these, so you know what to ask about next:
You don’t need to walk in with a diagnosis. You can simply ask, “What else could be causing this?” Here are tests worth asking about, depending on your symptoms:
| If You Have… | Ask About… |
|---|---|
| Fatigue, brain fog, cold or heat sensitivity | TSH, free T3 and T4, thyroid antibodies |
| Fatigue, hair shedding, restless legs | Ferritin and a complete blood count |
| Fatigue, tingling, low mood | B12 (and vitamin D if you’re at risk) |
| Shakiness, cravings, afternoon crashes | Fasting glucose, fasting insulin, A1c |
| Unrefreshing sleep, snoring, morning headaches | A sleep apnea screen |
| Cycle changes, night sweats, low drive | A review of your hormones in context, timed to your cycle when it applies |
A normal result isn’t the end of the conversation. Reference ranges describe where most people fall, not where you feel your best, so your symptoms and your labs belong together.
When someone tells me they’ve been told it’s stress, I look at the full picture:
When symptoms started, what changed, and how they come and go.
Bedtime, wake time, night waking, snoring, and morning light.
Thyroid with antibodies, ferritin, B12, vitamin D, fasting glucose and insulin, A1c, and hormones when the story fits. Sometimes I also look at cortisol rhythm across the day.
Timing, interactions, and side effects.
Work, family, caregiving, and whether you ever get a break. Stress is real, and I address it too.
I also use my four working patterns to organize what I find:
Wired at night, tired by day, 3 a.m. wake-ups
Fatigue, hair shedding, low iron, B12, or vitamin D
Blood sugar swings, cravings, stubborn weight
Puffiness, bloating, alcohol hitting harder
These are clues that organize questions. They don’t diagnose a cause.
Even when something else is going on, your stress load still matters. These help regardless:
A steady bedtime and wake time, and screens away an hour before bed.
It anchors your body clock.
Protein and fiber at every meal. (Here are protein sources that support hormonal stability.)
A walk counts, and a short walk after meals helps steady blood sugar too.
Especially in the afternoon and evening.
Time with people you trust matters.
Magnesium and other supplements may help some people, but check first if you take medications or have a health condition. You can also start with magnesium-rich foods.
If you and your provider decide magnesium is a fit, this is the one I use. Check first if you take medications or have kidney disease.
Products shown are available through my Fullscript dispensary. Farmacy Counter may earn a commission on purchases.
A few minutes of preparation makes the conversation more productive:
Please talk with your provider promptly if you have a racing or irregular heartbeat, unexplained weight loss, severe or worsening fatigue, or new symptoms that concern you. Call for emergency care right away for chest pain, shortness of breath, fainting, or sudden weakness.
If something feels off, keep asking. Stress may be part of your story, and it deserves care. But so do the other possibilities, and finding them can change how you feel.
If you haven’t yet, start with the free Hormone Type Assessment. And if you’d rather talk through what you’ve been experiencing, I offer a free discovery call. No pressure, just a conversation about whether functional medicine is the right next step for you.
Book Your Free Discovery Call →To your health and vitality, Dr. Ryan
Yes. When stress hormones like cortisol and adrenaline stay elevated for weeks or months, they can affect sleep, mood, blood pressure, blood sugar, and immune function. But the same symptoms can come from other causes, so stress shouldn’t be the only thing considered.
Thyroid problems, low iron (even without anemia), low B12, blood sugar swings, sleep apnea, perimenopause, low testosterone in men, and medication side effects can all cause fatigue, poor sleep, anxiety, and brain fog.
Depending on your symptoms, consider a thyroid panel (TSH, free T3, free T4, antibodies), ferritin with a complete blood count, B12, vitamin D if you’re at risk, fasting glucose, fasting insulin, and A1c, plus a sleep apnea screen or hormone review when the story fits.
Yes. Women with sleep apnea more often report insomnia, morning headaches, low mood, and fatigue than the classic loud snoring, which is one reason it gets missed.
Yes. Swings in estrogen and progesterone can cause sleep disruption, anxiety, irritability, brain fog, and fatigue, often before hot flashes begin.
For educational purposes only. Not a diagnosis, and not a substitute for care from your healthcare provider or a licensed mental health professional. Do not start, stop, or change any medication or supplement without talking with your provider.
