Why am I so tired in perimenopause? How to get your energy back
Why am I so tired in perimenopause?
Perimenopause fatigue is not ordinary tiredness. It is the kind of exhaustion that persists even after a full night's sleep, makes concentration feel like wading through fog, and leaves you wondering whether this is simply what getting older feels like.
It is not. And it is not something you have to accept.
As a Registered Nutritional Therapist who works primarily with women in perimenopause and menopause, fatigue is one of the most common complaints I hear in clinic. It is also one of the most responsive to targeted nutrition and lifestyle intervention. The key is understanding why it is happening in the first place.
Why perimenopause causes fatigue
During perimenopause, oestrogen and progesterone levels begin to fluctuate unpredictably before declining. This hormonal shift has far-reaching effects beyond hot flushes and irregular periods. Oestrogen plays a role in regulating blood sugar, supporting mitochondrial function (the energy-producing machinery inside your cells), and influencing the neurotransmitters that govern sleep and mood. When oestrogen becomes erratic, energy often follows.
Progesterone, meanwhile, has a naturally calming, sleep-supporting effect. As progesterone declines - often earlier than oestrogen - sleep quality tends to suffer first. Poor sleep compounds fatigue, which compounds stress, which further disrupts hormonal balance. It becomes a cycle that is hard to break without addressing the underlying physiology.
1. Balance your blood sugar
Blood sugar instability is one of the most overlooked drivers of perimenopausal fatigue. Oestrogen has a regulatory effect on insulin sensitivity, so as it declines, blood sugar management becomes less efficient. The result is more pronounced energy crashes after meals, stronger cravings for sugar and refined carbohydrates, and a general pattern of highs and lows throughout the day.
What to do
Every meal should contain a combination of protein, healthy fats, and fibre. This slows glucose absorption and prevents the sharp spike-and-crash pattern that drives afternoon energy dips. Practically, this means starting the day with a protein-rich breakfast rather than toast or cereal, avoiding eating carbohydrates alone, and not going more than four to five hours without eating during the day.
Reducing refined carbohydrates, ultra-processed snacks, and alcohol will also make a significant difference. Alcohol in particular disrupts blood sugar overnight, contributing to the 3am waking that many perimenopausal women experience.
2. Support your adrenal function
Your adrenal glands produce cortisol, your primary stress hormone. During perimenopause, they also take on a secondary role: producing small amounts of oestrogen to compensate for declining ovarian production. If your adrenals are already under strain from chronic stress, poor sleep, or high caffeine intake, this additional demand can leave you feeling profoundly depleted.
What to do
Adaptogenic herbs such as ashwagandha and rhodiola have good evidence for reducing cortisol and improving stress resilience. Ashwagandha in particular has been shown in clinical trials to reduce perceived stress and improve sleep quality - both directly relevant to perimenopausal fatigue. Always check with a registered practitioner before starting adaptogens, particularly if you are on any medication.
Reducing caffeine intake, particularly after midday, is also important. Caffeine extends the half-life of cortisol, meaning a mid-morning coffee can still be affecting your sleep at midnight.
3. Prioritise protein at every meal
Most women in perimenopause are not eating enough protein, and the consequences go beyond muscle loss. Protein provides the amino acid building blocks for neurotransmitters including serotonin and dopamine, which govern mood and motivation. It is also essential for stabilising blood sugar between meals and supporting the liver's ability to process and clear excess hormones.
What to do
Aim for a minimum of 30g of protein per meal. This is more than most women are currently eating, particularly at breakfast. Practical sources include eggs, Greek yogurt, smoked salmon, cottage cheese, tofu, legumes, and quality protein powder if needed.
Do not save your protein for dinner. Distributing it evenly across three meals does more for energy, muscle maintenance, and hormonal balance than loading it at the end of the day.
4. Investigate nutrient deficiencies
Fatigue in perimenopause is frequently compounded by nutrient deficiencies that go undetected because they are not routinely tested. The most clinically relevant ones are iron (particularly ferritin, the storage form), vitamin B12, vitamin D, and magnesium.
Iron deficiency is especially common in perimenopausal women who are still experiencing periods, particularly if cycles have become heavier. Even a ferritin level that sits within the "normal" laboratory range can be functionally low for energy purposes - many practitioners look for a ferritin of at least 50-70 mcg/L for optimal energy rather than simply above the lab's lower limit.
What to do
Ask your GP for a full blood count, ferritin, vitamin B12, vitamin D, and a thyroid panel (an underactive thyroid is also common in midlife women and presents almost identically to perimenopausal fatigue). If your GP is reluctant, private testing is accessible and relatively affordable.
Supplement based on your results rather than guessing. Taking iron when you are not deficient, for example, is not only ineffective but potentially harmful.
5. Address sleep at its root
Hormonal changes during perimenopause directly disrupt sleep architecture. Declining progesterone reduces the calming GABA activity that promotes deep sleep. Night sweats and hot flushes fragment sleep further. The result is that many women spend adequate hours in bed but wake feeling unrestored - because the quality of their sleep, not just the quantity, has deteriorated.
What to do
Magnesium glycinate taken before bed is one of the most evidence-supported interventions for improving sleep quality in this group. It supports GABA activity and muscle relaxation, and most women are deficient. Herbal support with valerian or passionflower can also be effective for sleep onset.
Keeping a consistent sleep and wake time - even at weekends - is more effective than most people expect. The body's circadian rhythm is sensitive to consistency, and irregular schedules undermine sleep quality regardless of how long you spend in bed.
Reducing alcohol is also non-negotiable for sleep. Even one to two units disrupts the second half of the sleep cycle, reducing REM sleep and contributing directly to morning fatigue.
When to seek personalised support
These five areas address the most common drivers of perimenopausal fatigue. But fatigue is rarely caused by just one thing, and the most effective approach is one that is tailored to your specific symptoms, blood test results, and health history.
If you have been exhausted for months, have tried the basics, and are still not seeing improvement, it is worth working with a registered practitioner who can assess the full picture - including thyroid function, adrenal health, nutrient status, and the role of HRT if appropriate.
I offer personalised nutrition consultations for women in perimenopause and menopause, with a focus on practical, evidence-based support that fits around real life.
Book a free 20-minute consultation to find out how I can help, or explore my Women's Health Nutrition Packages.
