Why Am I So Tired at 35–45?
You’re not lazy and you’re not “getting old.” Here’s why fatigue shows up now — and how to reset your body back to balance.
It’s a strange kind of exhaustion — not the kind a weekend nap will fix, but the kind that makes you wonder where the person you used to be has gone. Strong, ambitious, steady — and suddenly running on fumes.
The irony is, mentally we still feel young. This isn’t the same 40s our parents grew up with. We’re thriving, building, lifting heavier, running businesses, raising families, saying yes to adventures that used to belong only to our twenties. Half the time, we forget how old we actually are. And yet — the fatigue still finds us.
It’s not only the pace of life that leaves us drained. The truth is, while we’re out here thriving — mentally sharper, socially fuller, more ambitious than ever — our bodies are changing in ways no one prepared us for. Hormones begin to shift, the nervous system carries a heavier load, and hidden stressors stack up quietly until the crash hits. That’s why you can sleep a full night’s rest and still wake up foggy, crush the gym or a work deadline and still feel like you’re running behind your own body.
The good news: there are real, science-backed reasons why this fatigue shows up in your midlife. And once you understand them, you can begin to restore energy in a way that feels sustainable, not like another challenge to white-knuckle through.
1. Hormones and Energy Shifts at 35–45: The Rollercoaster Years
Around 35, hormone patterns start to shift. For some women it’s subtle; for others it feels like the floor drops out.
Estrogen fluctuations disrupt serotonin, the neurotransmitter that influences mood and sleep quality.
Progesterone dips can leave you restless at night, anxious during the day.
Cortisol misfires — too high at night, too low in the morning — explain why you’re wired at 11 p.m. and dragging at 7 a.m.
Add thyroid changes (which affect metabolism) and suddenly your baseline energy isn’t what it used to be. Research shows up to 45% of women over 40 struggle with sleep disturbances connected to perimenopause — so if you’re tossing and turning, it’s not “just stress.” And here’s the thing: perimenopause doesn’t mean you’re old. It’s simply another chapter your body moves through — like seasons shifting. For many of us, the word itself feels heavy, but the truth is, it’s not an ending. It’s your body asking for care in new ways, while you’re still very much in your prime.
💡 Reset tip: Expose yourself to natural light within 30 minutes of waking and move your body — even lightly — before checking your phone. It helps reset cortisol rhythm and restores your body’s natural “wake up” signal. I wrote a whole piece on the benefits of morning light if you want to go deeper into the practice.
2. The Invisible Mental Load That Drains Your Energy
Hormones and sleep aren’t the only drains. In your mid-30s and mid-40s, another kind of exhaustion shows up — the one you can’t measure on a lab report.
You know this decade is full and vibrant. We’re in our prime — killing it at work, stepping into leadership, building businesses, or finally doing what lights us up. Some of us are dating, some are married, some are changing relationships altogether. We’re more sure of who we are, making bolder decisions, and shedding old layers. Some of us are getting pregnant, some have toddlers tugging at our legs, some are raising teens with opinions as big as ours. It’s the best kind of chaos — thrilling, messy, alive.
And yet, even the excitement comes with a weight. There’s so much happening for all kinds of women in this season, and while it’s powerful, it can still be draining. The invisible load doesn’t take away from the fact that this might be the best decade of our lives — it just means our brains are running hot in the background, tracking dozens of “open tabs” at once. Research has shown — including a 2016 study in PNAS, one of the leading scientific journals — that this kind of cognitive overload actually changes brain activity in regions tied to motivation and focus. Translation: even in your prime, the mental load is real.
💡 Reset tip: Try a “download ritual” earlier in the evening — right after dinner works best. Write down three priorities for tomorrow and let the rest go. That way, your brain knows the list is safe, and the rest of the night can be a true pause and wind-down instead of mental rehearsal.
Because fatigue doesn’t take away from how good this season is — it just means your body deserves as much support as the life you’ve built. I go deeper into this in The Ritual That Tells Your Body It’s Safe to Rest.
3. The Gut–Brain Connection: How Food and Deficiencies Shape Energy
By this age, most of us have put our bodies through decades of stress, antibiotics, late-night takeout, or “survival meals” eaten on the go. All of it leaves an imprint on the gut — and because around 90% of serotonin is made there, imbalances don’t just affect digestion. They ripple into mood, focus, and energy.
The gut is often called the second brain, and neuroscience backs that up. The vagus nerve runs directly between the gut and the brain, carrying more information upward than downward. In other words, your clarity, calm, and energy often depend on what your gut is processing. When the system is fed real food, the signals that reach the brain support motivation and balance. When it’s overloaded with processed food, additives, and sugar, the signals are noisy, inflamed, and exhausting.
Deficiencies in iron, B12, and magnesium — all common in women at this stage — only add to the depletion, because they’re critical for energy production and neurotransmitter balance. The good news: you can start restoring them in simple ways. Iron shows up in leafy greens, beans, salmon, or red meat. B12 in eggs, fish, and legumes. Magnesium in pumpkin seeds, dark chocolate, and greens. If you’ve been dragging despite good sleep, a simple blood test can confirm whether supplements might help. And when you do supplement, cleaner forms without fillers are always easier on your system.
Another hidden drain? Blood sugar swings. Carb-heavy meals spike glucose, and when it crashes, your energy, mood, and focus crash right along with it. That’s the rollercoaster: surge → crash → cravings → exhaustion.
And then there’s coffee. Most of us lean on it to push through, but caffeine doesn’t actually create new energy — it just blocks adenosine, the chemical that signals sleep pressure in the brain. On an already taxed system, too much caffeine can spike cortisol, irritate the gut lining, and intensify the very fatigue you’re trying to fight. That doesn’t mean you need to give it up altogether — ritual matters, and joy matters — but how you drink it makes all the difference. Hydrating first, pairing coffee with protein instead of an empty stomach, and cutting it off by early afternoon can turn coffee from a crutch into a supportive tool.
💡 Reset tip: Start your day (or your first meal) with 30 grams of protein, paired with fiber and clean fats. Eggs, a Greek yogurt bowl with fruit and nuts, or even last night’s chicken all work. If you’re not hungry early, start small or push it to mid-morning — just don’t skip it. Giving your gut real, stable fuel is the simplest way to help your second brain send steady signals all day long.
And a quick note on intermittent fasting: I know it’s trendy and I’ve tried it myself. Some studies show benefits, but others suggest it can backfire for women — especially in our 30s and 40s when hormones are already shifting. For me, fasting left me foggier and more anxious, while a protein-rich first meal gave me steadier energy and focus. Everyone’s body is different, but if fasting leaves you wired or wiped out, your gut may be asking for something more nourishing.
4. Hidden Drains in Your Environment: Toxins, Sleep, and Everyday Stressors
Fatigue isn’t just internal. The environment you live in is quietly shaping your energy every single day — often in ways so subtle you don’t even notice until you hit the wall.
Blue light at night delays melatonin, keeping your brain wired when it should be resting. Endocrine disruptors in plastics, cleaning products, or skincare whisper the wrong signals to your hormones. And even your sleep environment matters more than you think: a room that’s too hot, fabrics that don’t breathe, or constant background noise can all disrupt slow-wave sleep — the deep, restorative phase your brain and body crave.
I used to fall asleep with Netflix buzzing on the nightstand and wonder why I woke up restless, wired, and foggy the next morning. Now, I don’t bring computers or TVs into the bedroom at all. Even my phone lives six to eight feet away — close enough if I need it, but far enough that I’m not tempted to scroll. Those small boundaries shifted everything.
Individually, none of these drains seem dramatic. But together, over years, they stack — confusing your hormones, keeping your nervous system on alert, and leaving you exhausted after what should have been a full night’s sleep.
💡 Reset tip: Create a buffer between your day and your night. Power down devices at least an hour before bed, and start with one swap in your environment — cleaner skincare, a non-toxic candle, breathable cotton sheets. You don’t need to overhaul everything overnight. Real shifts happen when the small, compounding choices remind your nervous system it’s safe to rest.
5. Nervous System Dysregulation: Why “Go Mode” Leaves You Exhausted
One of the most overlooked reasons for midlife fatigue is nervous system burnout. Think of it like this: your body has two gears. One is “go mode” — the fight-or-flight system that gets you through deadlines, workouts, traffic, toddler meltdowns. The other is “rest-and-repair” mode — the one that allows you to digest food, repair cells, and truly recharge.
The problem? Most of us spend decades living almost entirely in “go mode.” We push through long days, ignore our body’s signals, and tell ourselves we’ll rest later. Over time, the balance breaks. Your nervous system forgets how to switch gears, and you get stuck in high-alert. That’s nervous system dysregulation.
Science backs up what you feel: cortisol stays high at night when it should be low, blood sugar jumps around, and low-grade inflammation builds in the background. This is why you can sleep eight hours and still wake up tired — your body never believed it was safe enough to fully rest. And it’s also why so many women in their 30s and 40s go to the doctor with fatigue, brain fog, or body aches, only to be told their labs are “normal.” The symptoms are real — they just don’t always show up on standard tests.
Mindset plays a role too. If your brain interprets every curveball as a crisis, your body reacts as though you’re in danger — heart racing, cortisol pumping. But when you start reframing stress as something you can adapt to, your biology actually shifts. That’s not fluff, it’s neuroscience. (I dive deeper into this in The One Shift That Changes Everything You See.)
💡 Reset tip: The key is giving your body proof that it’s safe to switch gears. That looks different for everyone:
Journaling to download racing thoughts
Walking — outside if you can, or even a quick lap around the block
Creative outlets like art or design
Rolling out a mat for 20–30 minutes of Pilates, light weights, or just stretching. I treat it as a mental health break more than a workout, and it resets me every time.
Laughing with a friend, kid or partner, or petting your pet
And if you’re truly short on time, keep it simple: hum in the car, take three deep breaths at your desk, or literally shake it off for a minute. Even two minutes of intentional practice can remind your body it’s safe to rest again.
The Bottom Line: Reclaiming Steady Energy at 35–45
If you’re tired at 35–45, it’s not laziness. It’s not proof you’re “falling behind” or aging too fast. It’s your body asking for rhythm instead of more force.
I’ve lived that bone-deep fatigue — the foggy mornings, the irritability, the sense that life was moving faster than I could. What helped wasn’t another hustle plan or quick fix. It was peeling back the noise, clearing hidden drains, and giving my body the chance to remember what steady actually feels like.
Here’s the reframe that shifted everything for me: your body isn’t betraying you, it’s protecting you. Fatigue is its way of demanding recalibration, not punishment. Once you learn to listen, you’ll never confuse exhaustion with weakness again.
That’s what The Soft Reset is about — not another challenge to push through, but a way of living that restores flow, balance, and energy that lasts.
✨ To help you start, I created a free 7-Day Reset PDF — simple, science-backed rituals to calm your system and reclaim steady energy.
And because I know this stage of life comes with a thousand questions, I’ve pulled together some of the most common ones women ask about energy, fatigue, and midlife shifts. I’m not a doctor, and this isn’t medical advice — think of it as a place to start a conversation with your body, and with your healthcare provider if you need deeper support.
Frequently Asked Questions About Women’s Fatigue at 35–45
Why do I still feel tired even after getting 8 hours of sleep?
Because sleep quality matters more than quantity. Stress hormones like cortisol can keep you in lighter sleep stages, so you never reach the slow-wave cycles your brain needs to restore energy. And small “hidden drains” — blue light at night, synthetic bedding, even hormone-disrupting ingredients in skincare — can all interfere. You might be “asleep” for 8 hours, but your body hasn’t actually repaired. And here’s the part most people overlook: your morning routine matters just as much as your night one. Morning light helps set your body’s melatonin clock for later that night. (I go deeper into this in my article on the benefits of morning light.)
💡 Reset tip: Make your bedroom a cave for rest. Darken the room completely, cool it to 65–67°F, and choose breathable fabrics like cotton, eucalyptus, or linen. Those small swaps can add up to deeper, more restorative sleep.
What vitamins or minerals help with fatigue during midlife?
Iron, B12, and magnesium are three of the biggest culprits. They’re critical for energy production and nervous system balance, and deficiencies are common in women during this decade. Magnesium especially is tied to sleep quality and stress regulation. Bloodwork is the most reliable way to check, but even without it, most women benefit from building more nutrient-dense foods into their diet.
💡 Reset tip: Focus on food first. Iron in leafy greens, salmon, and red meat; B12 in eggs and legumes; magnesium in pumpkin seeds and dark chocolate. If you do supplement, keep it clean and simple — no fillers, just what your body needs.
Why am I suddenly crashing in the afternoon?
Afternoon slumps are usually blood sugar crashes in disguise. A carb-heavy breakfast or lunch spikes glucose, and when it drops, your brain panics and craves sugar or caffeine. That “2 p.m. wall” is your body asking for steadier fuel.
💡 Reset tip: Front-load your day with protein and fiber — think eggs with greens, Greek yogurt with nuts, or a smoothie built on a clean protein base. And if you love coffee, have it with food, not on an empty stomach. Pairing caffeine with protein helps you avoid a cortisol spike and keeps your energy curve steady. My favorite way to do this? A chocolate coffee protein smoothie when I’m on the run and don’t want to juggle 50 different cups or bottles. Protein, caffeine, and flavor — all in one.
Does exercise help or hurt when I’m already exhausted?
It depends on the type. Pushing through exhaustion with punishing HIIT or long cardio can actually spike cortisol and leave you more depleted. At this stage, strength training is crucial — it supports bone density, muscle mass, metabolism, and hormone balance. And the science is clear: women who build and maintain muscle live longer, healthier lives. A 2022 study in the British Journal of Sports Medicine found that doing strength training just twice a week lowered the risk of early death by up to 30%. Other research shows that higher muscle mass itself is directly tied to greater longevity and resilience.
I’ve found that I get better results from simple strength sessions at home than I ever did from high-intensity boutique classes. I keep a couple of dumbbells in my living room and mix in Pilates and walking for balance. I walk every single day, and if getting your steps in feels impossible, a walking pad can be a game-changer. And if time is tight, there are endless online platforms where you can stream workouts at home. My favorite is Fit with Coco, but the key is finding what feels sustainable — and not being afraid of weights. Strength doesn’t just build muscle, it builds confidence.
💡 Reset tip: Trade intensity for consistency. Strength training, Pilates, and walking will carry you further than endless HIIT sessions. Even a 20-minute walk — outside or on a walking pad — often restores energy better than an hour of punishing cardio. If you’re exhausted, think rhythm and flow, not force.
How can I support my energy naturally without relying on caffeine?
Caffeine can get you through the day, but it doesn’t actually create energy — it just blocks adenosine, the chemical that tells your brain you’re tired. That’s why the lift is temporary and often followed by a crash. Real, lasting energy comes from rhythm: light in the morning to set melatonin for night, mineral-rich hydration to replenish what stress depletes, and daily movement to literally move energy through your body. Sometimes that means a walk around the block, sometimes it’s rolling out a yoga mat, and sometimes it’s a two-song dance break in your car, your office, or wherever you are. Circulation and oxygen are what wake up your brain — not just caffeine.
💡 Reset tip: Instead of reaching for a second or third coffee, step outside for sunlight and movement, even just five minutes. Or swap your extra cup for matcha or green tea. You’ll still get a gentle lift, but the L-theanine balances the caffeine for calm, steady focus instead of jittery highs and afternoon crashes.
Can stress really make me this tired?
Yes. Chronic stress keeps your nervous system locked in “fight or flight,” which burns through energy reserves like a car idling in high gear. Cortisol stays elevated, blood sugar spikes more easily, and your body diverts resources away from long-term repair into short-term survival. Over time, this constant demand triggers inflammation — your immune system firing as if there’s a threat, even when there isn’t. That inflammation shows up as brain fog, muscle aches, slower recovery, and the kind of exhaustion you can’t sleep your way out of.
The longer your system runs this way, the more it adapts by downshifting — pulling energy back just to keep you alive. That’s why stress doesn’t just make you anxious, it makes you bone-deep tired. And this is often where disease begins. Chronic inflammation is the soil where conditions like heart disease, autoimmune flares, and metabolic disorders take root. It’s also why so many women go to the doctor with fatigue, pain, or brain fog and are told their labs look “normal.” The symptoms are real — they just don’t always show up on standard tests until years later.
And mindset matters too. If your brain interprets every curveball as a crisis, your body reacts like it’s under siege — cortisol rises, inflammation spikes, and fatigue deepens. Reframing those triggers isn’t fluff, it’s biology. (I wrote a whole piece on why mindset is the foundation for nervous system health if you want to dig deeper into the science and daily practices.)
💡 Reset tip: Build micro-resets into your day. Hum in the car, take three deep breaths at your desk, step barefoot into the grass, or literally shake it off for a minute. Even two minutes is enough to activate your vagus nerve, calm cortisol, and lower inflammation before it snowballs into something bigger. When your nervous system feels safe, your body can stop bracing for survival and finally release energy again.
