Fatigue & Low Energy in Women: Common Causes & What Helps

What Is Fatigue (and How Is It Different from Just Being Tired)?

What Fatigue Can Feel Like

Fatigue shows up differently for everyone, and it often blends physical and mental tiredness. You may recognise several of these — and noticing patterns (like timing around your period) is useful.

Common Causes of Fatigue in Women

Fatigue rarely has a single cause — it's often a few things adding up. Here are the most common reasons women feel persistently low on energy. Several of these are easy to test for and very treatable, which is why a check-up matters when tiredness lingers.

Iron-deficiency anaemia (low iron)

One of the most common causes of fatigue in women. When you don't have enough iron, your body can't make enough healthy red blood cells to carry oxygen — leaving you tired, breathless, pale or lightheaded. It's often linked to heavy periods, a diet low in iron, or pregnancy. It's diagnosed with a simple blood test and usually treated effectively with diet changes and iron supplements prescribed by a doctor.

Thyroid problems

An underactive thyroid (hypothyroidism) — where the gland makes too little thyroid hormone — is a classic cause of tiredness, often alongside low mood, feeling cold, weight gain and dry skin. It's common in women and easily checked with a blood test, and very manageable once diagnosed.

Poor or disrupted sleep

Not getting enough good-quality sleep is one of the biggest everyday drivers of fatigue — whether from late nights, broken sleep, caring for a baby or family, shift work, or an unsettled sleep routine. Even small, consistent improvements to sleep can make a real difference.

Stress, busy life and burnout

Ongoing stress, juggling work and home, caregiving and emotional load are exhausting in their own right. Chronic stress raises the body's stress hormones, disturbs sleep and appetite, and leaves you running on empty — a very common picture for women carrying a lot.

Your menstrual cycle & perimenopause

It's normal for energy to dip in the days before a period (as part of PMS) and during perimenopause, when shifting hormones can disturb sleep and mood. Heavy periods can also lead to low iron, which deepens tiredness. These cyclical patterns are recognisable once you start tracking them.

Low mood, anxiety and depression

Tiredness and low energy are core features of low mood, anxiety and depression — and the link runs both ways, as constant fatigue can also pull mood down. If you also feel persistently low, anxious, or have lost interest in things you used to enjoy, mental wellbeing deserves attention alongside the physical causes.

Diet, hydration & low energy intake

Skipping meals, irregular eating, very restrictive diets, low fluid intake or relying on sugar and caffeine can all leave energy spiking and crashing. Not eating enough — or not enough of the right foods — is an easily overlooked cause of feeling drained.

Other medical causes

Less commonly, fatigue can be linked to things like low vitamin B12 or vitamin D, blood sugar problems (diabetes), infections, certain medicines, or other conditions. This is exactly why persistent, unexplained tiredness is worth a doctor's assessment and some bloodwork — to find and treat what's behind it.

Treatment Depends on the Cause

There's no single 'fatigue treatment' — the right approach depends on what's driving it. That's why finding the cause is the key step. Here's how the common causes are typically addressed, alongside the self-care above.

Iron-deficiency anaemia

Iron-rich diet plus iron supplements prescribed and dosed by a doctor, and addressing the cause of the iron loss (for example, very heavy periods). Energy usually improves once iron stores recover.

Underactive thyroid

Diagnosed with a blood test and managed with thyroid medication and monitoring by a doctor. Tiredness, mood and other symptoms typically improve once levels are corrected.

Sleep & stress-related fatigue

Improving sleep routine, managing stress, sharing the load, and addressing any sleep disruption. Talking therapies can help when stress or burnout is significant.

Cycle- & perimenopause-related dips

Tracking the pattern, lifestyle steps, and treating heavy periods or low iron where present. A doctor can discuss options for troublesome perimenopause symptoms.

Low mood, anxiety or depression

Support for mental wellbeing — which may include talking therapy and, where appropriate, medication, alongside lifestyle steps. Treating low mood often lifts the fatigue with it.

Self-Care: Everyday Steps That Genuinely Help

For many women, fatigue improves a great deal with consistent everyday changes — most powerful when done steadily over weeks, not just on the days you feel exhausted. These steps also support your energy whatever the underlying cause, and complement any treatment your doctor recommends.

When to See a Doctor (and Why Bloodwork Helps)

Self-care is a good starting point, but please see a doctor — and ask about blood tests — if any of the following apply. Simple bloodwork (such as haemoglobin/iron studies, thyroid function and more) often finds a clear, treatable cause.

• Your tiredness has lasted for several weeks despite reasonable sleep and self-care
• Your fatigue is severe, getting worse, or stopping you doing everyday things
• There's no obvious explanation for how exhausted you feel
• You feel breathless, your heart races on mild effort, you look pale or feel lightheaded (possible anaemia)
• Your periods are very heavy or have changed — this can cause iron-deficiency anaemia
• You also feel cold, have gained weight, have dry skin or low mood (possible thyroid problem)
• You feel persistently low, anxious, or have lost interest in things you enjoy
• You have other symptoms alongside the tiredness that worry you

Frequently Asked Questions