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:

“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.

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.

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.”

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.

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.

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.

According to YouGov, a third of UK adults say they feel tired about half of the time.

Some research suggests 5-7% of people who see their GP complain of fatigue, and recent surveys say the average British adult only gets three nights of decent kip a week.

No wonder it feels like everyone, everywhere, is constantly exhausted.

But if we’re all so wiped out, how can we be expected to tell “normal” tiredness from more concerning fatigue?

Here, we asked Dr Suzanne Wylie, GP and medical adviser for IQdoctor, when to worry.

Speaking to HuffPost UK, Dr Wylie explained that fatigue “is a very common complaint in general practice and, in most cases, is related to lifestyle factors such as lack of sleep, stress, or overwork”.

But sometimes, it can be linked to underlying health issues – and its persistence can be a red flag.

“As a GP, I would suggest that you should start to worry about fatigue if it is persistent, lasting more than a few weeks, or if it is unexplained by your usual activities or recent events,” she said.

Aside from longer-lasting fatigue, exhaustion with other symptoms should be investigated, too.

“You should also seek medical advice if the tiredness is accompanied by other symptoms such as unintentional weight loss, night sweats, fevers, breathlessness, chest pain, persistent cough, or changes in bowel habit,” the GP said.

Meanwhile, fatigue linked to low mood, disrupted sleep, and a loss of interest in hobbies “may indicate depression or anxiety, which also warrants assessment”.

She added, “Additionally, if you notice symptoms such as increased thirst or urination, palpitations, dizziness, or heavy menstrual bleeding, it could point towards conditions like diabetes, thyroid disease, or anaemia”.

Per the NHS, you should see your doctor if fatigue lasts longer than a few weeks, if it affects your day-to-day life, and/or if you’ve noticed other symptoms like unexplained weight loss or mood changes.

And if your partner or someone else tells you you’ve been “making gasping, snorting or choking noises when you’re asleep,” visit your doctor as this could be a sign of sleep apnoea.

“In short,” Dr Wylie ended, “while occasional tiredness is normal, persistent or unexplained fatigue, especially when associated with other symptoms, should always prompt a review with your GP”.