One in eight people in the UK say they feel tired “all the time,” YouGov reported in 2022. In fact, the feeling is so common that the NHS says it has its own acronym, TATT (tired all the time). But while the health service said most causes of TATT are “obvious,” like overwork or having a young child, Amir Bhogal, director and superintendent pharmacist at Pyramid Pharmacy Group, told us that “there are several hidden causes that may be easy to overlook”. Here, he shared seven potential causes: 1) Iron deficiency “Iron helps transport oxygen throughout the body via red blood cells. When iron levels are low, your body struggles to carry enough oxygen to your muscles and organs, leading to constant tiredness and weakness,” Bhogal said. These are common signs of iron deficiency anaemia . Others include shortness of breath, headaches, paler than usual skin, and palpitations. It “is surprisingly common, especially among women, due to regular menstrual blood loss, as well as those who follow a strictly vegetarian or vegan diet. While symptoms can be subtle at first, fatigue can interfere with daily activities and overall quality of life,” Bhogal added. A blood test can confirm whether you have iron deficiency anaemia. 2) Thyroid issues The thyroid is a gland in your neck that produces hormones. These affect things like your heart rate and body temperature. “An underactive thyroid (hypothyroidism) can slow down metabolic processes and reduce the body’s ability to produce energy efficiently, leading to sluggishness or temperature sensitivity,” Bhogal said. And an overactive thyroid can do the opposite, causing bursts of energy sometimes followed by crashes. It can create difficulty sleeping, too. “Thyroid issues can develop slowly, with subtle symptoms ranging from unexplained changes in weight and mood, as well as dry skin or thinning hair. However, blood tests can confirm a thyroid imbalance,” the pharmacist said. 3) Low blood pressure Though high blood pressure can make you tired, that usually happens indirectly through organ changes or associated lifestyle choices. But “low blood pressure (hypotension) can also sap energy,” the pharmacist told us. “When blood pressure is too low, your organs and muscles may not receive enough oxygen-rich blood, leading to dizziness and constant tiredness.” Sometimes, he added, low blood pressure can be created by dehydration, nutritional deficiencies, and some medications, and even some heart conditions. “If fatigue is accompanied by lightheadedness or fainting, please consult with a medical professional immediately,” Bhogal stated. “Getting your blood pressure tested regularly, even without symptoms, can help detect underlying issues early and support long-term health.” 4) Dehydration Lots of us don’t drink enough water in winter , but Bhogal said this mistake could be making us very tired. “Water is essential for just about every function in the body, including energy production. Even just mild dehydration can reduce blood volume, making the heart work harder and leaving you feeling lethargic,” he told us. “The reality is that many people underestimate their daily fluid needs, especially when the weather is warm, or they are physically active. Instead, they compensate with sugary drinks, alcohol, or caffeine, all of which are diuretics that can worsen dehydration.” Drinking more water and eating more water-rich foods, like fruits and vegetables, can help a lot. 5) Chronic infections Sometimes, conditions like the flu or glandular fever can stay in your system for longer than you realise. This, Bhogal explained, can keep you feeling run-down after sneezes, sniffles, and sore throats have abated. This, he continued, can even be the case with UTIs and chronic sinusitis . “Often, these infections present with subtle symptoms like low-grade fever or mild muscle aches that are easy to dismiss. Identifying the underlying infection usually requires medical testing, and treatment may involve antibiotics or antiviral therapy to restore energy levels,” he said. 6) Sleep conditions When it comes to feeling rested, sleep quality can sometimes matter as much as the number of hours slept. And, Bhogal said, “Frequently waking up can be caused by environmental disturbances, and sometimes from conditions like sleep apnoea or restless leg syndrome, which can prevent the body from entering deep, restorative rest. “Fatigue caused by poor sleep often presents as brain fog and irritability that manifests as low motivation throughout the day. Overuse of electronic devices before bedtime can also interfere with the natural sleep cycle, so I advise putting away gadgets at least two hours before bedtime.” If you’re concerned about your sleep, speak to your GP.