Energy & Fatigue

Nurse Note: Feeling cold and tired is common, but it should not be dismissed when it is persistent, worsening, or paired with symptoms such as heavy bleeding, breathlessness, palpitations, weight change, low mood, hair loss, dizziness, or changes in periods. Introduction “Why am I always cold and tired?” is one of those questions many women ask quietly before they ever bring it up in a clinic. You may notice you are wearing extra layers when everyone else is comfortable, needing more coffee to get through the afternoon, or falling asleep on the sofa even after a full night in bed. If this sounds familiar, you are not being dramatic. Feeling cold and exhausted can happen for simple reasons such as poor sleep, stress, under-eating, or being run down. But when it is persistent, new, worsening, or affecting your work, relationships, mood, confidence, or daily life, it deserves attention. For women aged 35–65, the answer is often not one single thing. Hormonal changes, thyroid function, iron levels, vitamin B12, sleep disruption, heavy periods, stress, metabolic changes, and chronic health conditions can all overlap. Many women are told they are “just busy,” “just getting older,” or “probably menopausal,” when in reality they may need a proper health check. This guide explains the common reasons behind feeling cold and tired, what symptoms to look for, what tests may help, and when to seek medical advice. What research and clinical guidance show: Feeling cold and tired can be linked to several evidence-recognised causes, including underactive thyroid, iron deficiency anaemia, vitamin B12 or folate deficiency, diabetes, sleep disorders, depression, chronic stress, medication effects, and menopause-related sleep disruption. Strength of evidence: Strong for hypothyroidism, anaemia, B12 deficiency, diabetes, and sleep disruption as recognised causes of fatigue. Moderate for the role of perimenopause and menopause in fatigue, largely because tiredness often results from several overlapping factors such as night sweats, insomnia, mood changes, muscle aches, and life stress. Areas of uncertainty: Fatigue is non-specific. This means the symptom alone does not point to one diagnosis. Blood tests, symptom history, menstrual history, medication review, and sometimes further assessment are needed to understand the cause. Key Statistics Box Women are more likely than men to develop thyroid disease, especially after pregnancy and after menopause. The NHS lists tiredness and feeling colder than usual as common symptoms of an underactive thyroid. Iron deficiency anaemia is the most common type of anaemia, and heavy periods are a common reason women develop low iron. WHO describes anaemia in women of reproductive age as a continuing public health concern globally. Menopause symptoms commonly occur during the 40s and 50s, and sleep disruption from night sweats can make fatigue worse. What Is Feeling Cold and Tired? Feeling cold and tired is not a diagnosis. It is a symptom pattern. In medical terms, “feeling cold” is often described as cold intolerance, which means you feel unusually sensitive to cold temperatures compared with other people around you. “Tiredness” may mean fatigue, low stamina, sleepiness, muscle weakness, poor concentration, or a heavy, drained feeling that rest does not fully fix. When a woman asks, “Why am I always cold and tired?” the most helpful approach is to look at the body systems that regulate energy, oxygen delivery, hormones, metabolism, sleep, and circulation. Common causes include: Underactive thyroid, also called hypothyroidism. Iron deficiency or iron deficiency anaemia Vitamin B12 or folate deficiency Perimenopause or menopause-related sleep disruption Heavy or prolonged periods Low calorie intake, restrictive dieting, or low protein intake Chronic stress or burnout Depression or anxiety Diabetes or blood sugar imbalance Poor sleep quality or sleep apnoea Certain medications Chronic infection, inflammatory conditions, or autoimmune disease The important thing is this: being always cold and tired is not something you have to “push through.” It is a signal worth listening to. What Causes Cold Intolerance and Fatigue? a. Underactive Thyroid One of the most common medical reasons women feel cold and tired is an underactive thyroid, also known as hypothyroidism. The thyroid is a small butterfly-shaped gland in the front of the neck. It produces thyroid hormones that help regulate metabolism, body temperature, heart rate, digestion, skin and hair, mood, and energy. When thyroid hormone levels are too low, many body processes slow down. This can make you feel cold, sluggish, constipated, low in mood, foggy, and unusually tired. Symptoms may include: Feeling cold when others feel comfortable Extreme tiredness Weight gain or difficulty losing weight Constipation Dry skin Hair thinning or hair loss Low mood or depression Brain fog Heavy or irregular periods Hoarse voice Muscle aches Slower heart rate Many women notice these symptoms gradually. They may blame work stress, ageing, poor sleep, motherhood, caring responsibilities, or menopause. But if you are asking “why am I always cold and tired?” and you also have weight changes, constipation, hair thinning, dry skin, or heavy periods, thyroid testing is worth discussing with your GP or clinician. b. Iron Deficiency and Anaemia Iron helps your body make haemoglobin, the protein in red blood cells that carries oxygen. If your iron stores are low, your tissues may not get oxygen as efficiently. That can leave you exhausted, breathless, dizzy, pale, weak, or cold, especially in your hands and feet. Iron deficiency can happen with or without anaemia. Anaemia means your haemoglobin level is low. Iron deficiency means your iron stores may be low, even before haemoglobin drops. Women are at higher risk when they have: Heavy periods Long or frequent periods Fibroids Endometriosis or adenomyosis Recent pregnancy or breastfeeding Low iron intake Vegetarian or vegan diets without careful planning Gut conditions that affect absorption Gastrointestinal bleeding Use of some medications that irritate the stomach A common real-life pattern is the woman who says, “I’m exhausted, freezing, dizzy when I stand up, and my periods are flooding.” That combination should not be brushed off as normal midlife stress. c. Vitamin B12 or Folate Deficiency Vitamin B12 and folate help the body make healthy red blood cells and support nerve