If you're reading this through bleary eyes – or contemplating yet another cup of coffee – you're far from alone.

As many as one in eight of us feels 'tired all the time', according to a 2022 YouGov survey, with a quarter of Britons saying they feel tired 'most' of the time.

In fact, it has its own acronym among medics – TATT, or tired all the time. But untangling the causes is far from straightforward. For when we say we're 'tired', we can mean we are sleepy, physically exhausted, drained, lacking in energy or motivation, or a combination of all of these.

A study published earlier this year linked fatigue to more than 100 different eventual diagnoses – from depression and sleep disturbances to underactive thyroid and urinary tract infections.

The research, published in the British Journal of General Practice, was based on the medical records of people who'd seen their GP about new tiredness symptoms compared with those who didn't report fatigue (about 700,000 patients in total).

Here, five people who were 'tired all the time' – for very different reasons – tell their stories…

I just thought it was 'mum' tiredness

'It started in my mid-30s just after the birth of my second child,' says Kate Cartledge, 43, from Sevenoaks, in Kent. 'I thought it was just 'mum' tiredness from running around after the kids, as well as working, but it just wouldn't go away.'

It left Kate unable to concentrate and feeling low. But she didn't think she was suffering from depression: 'I felt sure it was something else but didn't know what it was,' says Kate, who runs a property business with her husband Tim, 54.

Another concern was her bones. 'I'd broken several in my youth,' she says but since having her children – now aged seven and 12 – Kate had broken her lower leg and her shoulder when skiing, then her toe tripping up the stairs aged 41.

Kate sought advice about her bone density at a private clinic – and was diagnosed with early menopause.

'Tiredness and fatigue are common symptoms that can indicate premature menopause as well as menopause – although many women may not realise this,' says Dr Shazia Malik, a consultant obstetrician and gynaecologist and UK medical director of the online women's health clinic DAYE.

She adds that a spontaneous (natural) early menopause affects approximately 5 per cent of women before the age of 45.

'It occurs because of the complex hormonal changes; as oestrogen and progesterone levels fluctuate and decline, it can disrupt sleep patterns and lead to insomnia or poor-quality sleep.

'The hormonal fluctuations can also cause night sweats, which further interrupt restful sleep,' she says.

Kate began HRT and two years on has 'never felt better'.

She says: 'I feel like I am in my 20s again and the tiredness has gone. I feel refreshed and even have my libido back and have more energy for my children.

'Best of all, I know the oestrogen will protect my bones from now on.' (Oestrogen slows down the rate at which bone is broken down in the body.)

Exhausted after a good night's rest

'I'd have a full night's sleep and still feel exhausted the next day,' says Claudia Delrio, 31, a London PR manager. 'At first I ignored it and tried going to bed earlier – but nothing helped. It was a different kind of tiredness: all consuming. I'd have to sleep the moment I got in from work.'

Her regular GP was fully booked so she saw a doctor at a hospital clinic who told her it was nothing to worry about.

By now she was also breathless, so he sent her home with an inhaler. But a few weeks later, the tiredness was even worse and she started getting a very itchy scalp and skin. 'I went back to my GP who still didn't take me seriously.'

In despair, Claudia flew back to her home country, Italy, in April 2023 and saw a doctor there. She was immediately referred for tests and got her diagnosis: non-Hodgkin lymphoma.

'It was stage 2 – in my lymph nodes – and I also had a 14cm tumour in my chest. The tiredness had been there for months and I knew something was wrong but had no idea it would be something this bad.'

'Non-Hodgkin lymphoma is a form of blood cancer that affects white blood cells called lymphocytes, which are an important part of your immune system,' explains Dr Daniel Hodson, a consultant haematologist, and lead researcher on a Blood Cancer UK-funded project.

'Blood cancers are difficult to detect because the symptoms are quite non-specific.'

Extreme fatigue being one: 'We're talking about tiredness that doesn't go away even after rest or sleep,' says Dr Hodson. 'However, tiredness by itself is very rarely the only presenting symptom of lymphoma.'

Other common symptoms include swollen glands in the neck, around the collarbone, armpits, groin or other parts of the body (these may appear unexpectedly and be painless), along with high temperature (fever), unexplained weight loss and night sweats that soak nightwear and bedding.

It causes fatigue because 'if you have non-Hodgkin's lymphoma your body is constantly fighting against itself,' explains Dr Hodson.

'People with the disease often have low red blood cell counts, which limits the amount of oxygen their bodies can receive. The disease can also lead to chemical imbalances in the body, resulting in tiredness.'

While extreme fatigue can be a warning sign of many types of cancer, research suggests it's unlikely to be why most people see their GP about tiredness.

The 2024 study published in the British Journal of General Practice concluded that the only exception to this was in men aged over 80, with the researchers suggesting GPs should prioritise investigations for cancer if they present with new fatigue.

Fortunately, Claudia was able to start chemotherapy straight away, with treatment lasting six months. She was declared clear of cancer in May this year.

'The tiredness was a different kind of exhaustion, like nothing I'd ever experienced.

'I just wish doctors had taken me seriously sooner.'

Needed sleep hours after getting up

'I still recall one night two years ago waking in an extreme panic with a sense of dread, as if I was dying,' recalls Ben Jarvis, 48, who runs a space industry events company. 'But I had no reason for this and struggled to sleep afterwards.'

In the nights that followed, it happened again and again.

'Soon I was too tired to stay awake during the day and I'd have to go to bed three hours after waking up in the morning,' says Ben, who lives in Norwich.

His GP ran tests for everything from thyroid function to tumours on his adrenal glands (which produce hormones that regulate metabolism and stress response and other processes).

'Everything came back negative, yet I was becoming more and more tired. I run my own business and it involves organising events and meeting clients but sometimes I was so exhausted I was scared to drive.'

This went on for two years before, one day, Ben was explaining his symptoms to a friend who said: 'Could it be sleep apnoea?'

'Sleep apnoea is a relatively common condition where your breathing is interrupted during sleep,' says Dr Alanna Hare, a consultant in sleep and ventilation at Royal Brompton Hospital.

'Your breathing can stop and start repeatedly, sometimes hundreds of times a night.

'Obstructive sleep apnoea is the most common type and occurs where there are repetitive narrowings/closures of the upper airway, resulting in a drop in oxygen levels at nighttime.

'Tiredness is an early sign because the repeated drops in oxygen levels at night, as well as the effort to get air in and out through the narrowed airway, disrupts your sleep. This is because your brain is very sensitive to the lower oxygen levels and will wake you, or at least rouse you into a lighter sleep stage.

'This wakens the muscles in the neck, opening the airway up again and allowing air to flow and oxygen levels to rise, so you can fall back to sleep.

'These disruptions can occur several times an hour and results in sleep being less refreshing, so you are tired in the daytime and may struggle with concentration or mood.'

Ben went to his GP and asked about sleep apnoea – and was then referred to an NHS sleep clinic where he was diagnosed with the condition. He was then given a CPAP machine – which works by delivering a continuous stream of pressurised air through a mask that's worn over the nose or mouth as you sleep.

'A CPAP machine holds the airway open with air pressure,' explains Dr Hare. 'Special mouthguards called mandibular advancement splints can also be effective in some patients. And there are newer therapies which can stimulate the muscles in the neck via electrical impulses, which are available in some centres.'

Ben says: 'Within three days of using the CPAP machine I felt as if I was awake for the first time in years – colours were brighter, I could smell things again. I realised I'd been so tired for two years it had affected all my senses.'

So tired felt faint doing workouts

Usually full of energy, PR executive Julie Thompson Dredge suddenly found herself exhausted, two years ago. 'I was sleeping whenever I could – which was not easy, as I work a lot and have two young children,' says Julie, 46, from Liss, Hampshire. 'It got gradually worse until I started feeling faint whenever I did workouts.'

At first, Julie thought perhaps she'd caught a bug or was just run down. But after feeling this way for several weeks, she saw her GP who ordered blood tests.

'A few days later, I got a text with the results saying I had vitamin B12 deficiency. I was worried as I had a diagnosis, but no other information.'

She adds: 'It was a huge surprise, as I eat well and have a balanced diet, and am pretty healthy.'

'There are two main reasons why tiredness occurs with B12 deficiency,' says Dr Sue Pavord, a consultant haematologist at Oxford University Hospitals.

'B12 is an essential vitamin [found in meat, fish, eggs and dairy] which means you need to get it from your diet.

'It's needed for the normal function of body cells and for making DNA. If cells don't function properly the body will be fatigued. Levels become low if people do not have enough in their diet or if they do not absorb it properly.'

This can be a problem for some people on a vegan diet (which is why the Vegan Society advises taking B12 vitamin supplements or ensuring their daily diet includes foods fortified with the vitamin, such as breakfast cereals).

Dr Pavord adds that B12 deficiency affects around one in 20 people, rising to one in ten people over 75, as the body becomes less efficient at absorbing the vitamin with age.

Another reason B12 deficiency causes tiredness is because it leads to anaemia, a condition where there are not enough red blood cells, which transport oxygen around the body.

'Tiredness is very common in anaemia because of lack of oxygen in the body tissues and because the heart needs to pump faster and harder to make up for this,' says Dr Pavord.

'There are lots of reasons why people may get anaemia. For example, if they are bleeding, or have heavy periods, or not getting enough iron [iron is also needed to produce red blood cells].'

When she saw her GP again, Julie was told she would need to take vitamin B12 pills daily. She was diagnosed with anaemia at the same time.

'I have to say I've had no support from the doctors about it, and when I asked for further discussion with a doctor, it was really hard to make an appointment. So, at this stage, I really don't know why I have vitamin B12 deficiency or iron deficiency.'

Dr Pavord says: 'The treatment is to replace B12. This can be with a course of tablets if it is due to not having enough in the diet.

'But if further tests suggest it is because of poor absorption it needs to be replaced by regular injections in the muscle, usually every 3-6 months.'

'GP assumed it wouldn't be my thyroid as I'm a man'

'I work long hours and was usually awake and raring to go but, suddenly, I was falling asleep during the day,' says Vivek Angra, 59, a businessman from Amersham, Buckinghamshire.

'At first I wondered if I wasn't eating enough, so I increased my protein and made an effort to eat more healthily. But it didn't help – and no matter how much I slept at night, I was exhausted the following day.'

After a few months, Vivek saw his GP – but it wasn't until he'd been back several times that the doctor agreed to do blood tests.

'He kept saying it was just tiredness from getting to midlife,' says Vivek. 'Finally, after a year, I was diagnosed with hypothyroidism – an underactive thyroid. The GP said he hadn't considered tiredness a sign of this as it's more common in women.'

It's true that hypothyroidism is more common in women (possibly because the most common cause is an autoimmune condition that attacks the thyroid – and autoimmunity

is more prevalent in women). Indeed, for women, hypothyroidism was among the top three conditions linked with GP consultations for fatigue, reported the British Journal of General Practice earlier this year. But it's still relatively common in both sexes.

Professor Kristien Boelaert, a consultant endocrinologist in Birmingham, says: 'Tiredness is a common symptom of hypothyroidism. Of the patients I see – men and women – at least 60-80 per cent report this symptom.

'Your thyroid hormones regulate your metabolism, so if you have too much, you get a speeding up of the metabolism, whereas in hypothyroidism the thyroid doesn't make enough and everything slows down. The main symptoms are weight gain, constipation, mental slowing and excessive tiredness.'

Vivek was put on levothyroxine, a synthetic form of thyroid hormone. 'It took around a year to get the levels right but, once it was correct, I noticed a huge difference,' he says. 'The lethargy disappeared and I felt so much better.'

For more information, go to btf-thyroid.org