You sleep and still wake up drained. Coffee quits working by noon. And your feed is full of supplements promising to bring your energy back.

Some of those options are worth a conversation. But the most common reasons a woman in her 40s is exhausted can be found with one blood draw and a few screening questions. And no supplement can fix low iron or an underactive thyroid.

The most common reasons you're this tired

A good fatigue evaluation starts with your history and exam. Ordering every lab under the sun changes the plan for only about 5% of patients (Latimer et al., 2023). So we go after the high-yield causes.

• Thyroid TSH first, with free T4 and thyroid antibodies added when symptoms point to an autoimmune cause. More on thyroid care.
• Iron deficiency Ferritin is the key test for women who still have periods. Low iron causes fatigue even when you're not anemic.
• Anemia A complete blood count catches it.
• Blood sugar An A1c or fasting glucose checks for diabetes and prediabetes.
• B12 and vitamin D Both common. Both easy to correct once you know.
• Kidneys, liver, and electrolytes A comprehensive metabolic panel covers all three.

And because women in perimenopause can still ovulate, a pregnancy test belongs on the list before any treatment starts (Crandall et al., 2023).

What blood work won't show you

Some of the biggest energy drains never show up on a lab report.

• Sleep apnea Snoring, pauses in breathing, morning headaches. Sleep-related breathing problems and depression are the most common causes of fatigue that won't go away (Maisel et al., 2021).
• Depression and anxiety About 1 in 10 women in perimenopause has a major depressive episode. We screen with short, validated questionnaires. Read perimenopause or depression.
• Medications and alcohol Sleep aids, antihistamines, some blood pressure medications, and the nightly glass of wine all cost you energy.
• Perimenopause itself Night sweats, 3am waking, and hormone swings wreck sleep, and sleep drives everything else. See perimenopause symptoms at 40.

But you don't need a hormone blood test to be diagnosed with perimenopause if you're 45 or older with typical symptoms. It's a clinical diagnosis, because FSH and estradiol swing too much from day to day to be reliable (Crandall et al., 2023; Hamoda et al., 2024).

Thinking about energy trends? Check these first

Mitochondrial support products get a lot of attention for energy, and it's easy to see why. But the research on fatigue in people is still early. And nothing sold for energy can correct the things on the list above. If your ferritin is low or your thyroid is underactive, that's what needs treating, and you'll feel the difference.

So the smartest first step is simple. Make sure a common, treatable cause isn't behind your exhaustion. Then we can talk through other options honestly, with your labs and history in front of us.

The supplement with the most research

If you want a starting point with strong human data, it's CoQ10. A review of 13 randomized trials with more than 1,100 people found it reduced fatigue, with very few side effects (Tsai et al., 2022). A CoQ10 and NADH combination also improved fatigue in a trial of people with chronic fatigue syndrome (Castro-Marrero et al., 2015).

But even these work best after the workup, not instead of it. And there's no validated mitochondria test to order first yet. A commercial mitochondrial energy test didn't hold up when independent labs tried to replicate it (Tomas et al., 2019), so the standard workup is still the most useful place to start.

How we approach fatigue at Navara Health

We start with your story. Then the core labs and screening questions above. Then we treat what we find, whether that's low iron, your thyroid, sleep apnea, mood, or perimenopause.

And if you're interested in other options after that, we'll walk through them with you, including what the research shows so far, so you can decide with your eyes open.

Already had labs that came back "fine"? Read labs normal but you feel terrible, or see what labs to ask for.

Frequently asked questions

This article is general health information, not medical advice, and does not create a patient relationship. Don't start or stop any medication or supplement without talking to your provider. If you are having a medical emergency, call 911.