Why Am I Always Tired? Causes, Checks and When to See a Doctor

Most people who are always tired are short on sleep, sleeping at irregular times, stressed, or feeling the effects of alcohol, caffeine, diet or too little activity. But tiredness that has lasted a few weeks with no clear reason can be a sign of a medical condition, such as depression, anaemia, a thyroid problem, diabetes or sleep apnoea, so see a GP or doctor.

Below: the everyday causes to rule out first, the medical causes a doctor will look for, how to prepare for your appointment, and the signs that need urgent help.

Is it normal to feel tired all the time?

Feeling tired sometimes is normal. The NHS page on tiredness and fatigue (UK guidance; elsewhere, follow your own doctor's advice) says that if you are tired all the time and do not know why, it could be a sign of a problem. One NHS GP practice, Hadwen Health, notes that unexplained tiredness is one of the most common reasons people see their GP.

What doctors usually find is reassuring. A 2016 review of 26 primary care studies by Stadje and colleagues looked at people who saw a family doctor mainly because of tiredness. Depression was the most common diagnosis, in 18.5%. Anaemia was found in 2.8% and cancer in 0.6%. Serious physical disease was rare, but rare is not never, so persistent tiredness still deserves a proper check.

What is the most common cause of constant tiredness?

For most people it is how they live and sleep. The NHS lists not getting enough sleep or insomnia, an unhealthy lifestyle, stress, depression, life challenges such as bereavement or a new baby, hormonal changes such as pregnancy or the menopause, illnesses such as glandular fever or COVID-19, and some medicines. Hadwen Health adds that psychological causes are much more common than physical ones.

Not enough sleep

The NHS guide to insomnia says adults need 7 to 9 hours on average, and that you probably are not getting enough if you are constantly tired during the day. In a 2003 lab study by Van Dongen and colleagues, healthy adults kept to 6 hours or less in bed for 14 nights built up deficits in attention and thinking equivalent to up to 2 nights of total sleep deprivation. Their sleepiness ratings barely rose after the first days.

Irregular sleep, shifts and naps

The NHS self-help tips for tiredness recommend going to bed and getting up at the same time every day and avoiding daytime naps. Hadwen Health notes that night workers tire more easily, especially when shift times keep changing.

Caffeine and alcohol

The NHS says caffeine's effects can last up to 7 hours and can disrupt sleep, leading to daytime tiredness. Cut down gradually, because stopping suddenly can cause headaches and poor sleep. Alcohol may help you fall asleep, but you sleep less deeply and can be tired the next day even after a full 8 hours. Our guides to caffeine and sleep and alcohol and sleep go into the detail.

Activity, food and drink

Regular exercise makes you less tired in the long run, says the NHS, and even a single 15-minute walk can give you an energy boost. Build up gradually towards 2 hours 30 minutes of moderate activity a week. Hard training without enough recovery can tire you too: our guide on why HRV drops covers the signs. The NHS also suggests regular meals every 3 to 4 hours and a glass of water if you might be mildly dehydrated.

Stress and medicines

Stress uses up a lot of energy, and a bereavement, redundancy or break-up can leave you exhausted. The British Heart Foundation adds that some medicines cause tiredness, including beta blockers, water tablets, sleeping tablets and some anxiety medicines. Do not stop a prescribed medicine yourself: ask your GP or pharmacist to review it.

Why am I always tired no matter how much I sleep?

If you spend long enough in bed and still wake exhausted, look at the quality of your sleep and at medical causes. The NHS lists still feeling tired after waking as a symptom of insomnia. Sleep apnoea, where breathing stops and starts during sleep, causes loud snoring, gasping or choking and waking a lot, then heavy tiredness and morning headaches. It can be hard to tell if you have it, so the NHS suggests asking someone to watch you sleep. If you keep waking in the early hours, our guide to why you wake up at 3am covers the common causes. If you nod off during the day, our guide to the Epworth Sleepiness Scale explains the questionnaire many doctors use.

Medical causes of tiredness a GP will look for

The NHS is clear: your symptoms might give you an idea of the cause, but do not self-diagnose. See a GP if you are worried. The table lists conditions the NHS links with tiredness and the other symptoms it describes. Having one of these symptoms does not mean you have the condition.

The British Heart Foundation adds heart conditions, such as heart failure and irregular heart rhythms.

The NHS says you may need blood tests to check for anaemia, diabetes or thyroid problems, and a GP may refer you to a specialist if the cause is not clear. Treatment depends on the cause, from iron tablets to talking therapies such as CBT. Guessing with supplements means treating something you have not confirmed.

When to see a GP or doctor about tiredness

The NHS advises seeing a GP (or your own doctor outside the UK) if:

• you have been feeling tired for a few weeks and you are not sure why
• your tiredness affects your daily life
• you feel tired and have other symptoms, such as weight loss or mood changes, or you have been told you make gasping, snorting or choking noises when you are asleep

Other NHS pages add more triggers: symptoms of depression for most of the day, every day, for more than 2 weeks, and losing weight without changing your diet or exercise. Do not drive when you feel sleepy.

When tiredness needs urgent help

• Possible diabetes. The NHS says ask for an urgent GP appointment or get help from NHS 111 if you or your child has symptoms of diabetes.
• Heart symptoms. Call 999 or go to A&E if you have heart palpitations that do not go away, or palpitations with chest pain, shortness of breath, or feeling faint or fainting.
• Your mental health. For urgent help, ask for an urgent GP appointment or call 111 and select the mental health option. Call 999 or go to A&E if someone's life is at risk or you do not feel you can keep yourself safe. Samaritans are on 116 123. See the NHS page on where to get urgent help.

Hadwen Health also asks patients to book as soon as possible if tiredness comes with significant unexplained weight loss, coughing up blood, difficulty swallowing, bleeding from the back passage, a change in bowel habit for more than 3 weeks, a breast lump or bleeding after the menopause, or enlarged glands and night sweats. Outside the UK, use your local emergency or urgent care number.

How to prepare for your appointment

The British Heart Foundation suggests keeping a fatigue diary. Clear notes help a GP make sense of a vague symptom.

1. Write down when it started and what changed around then: an illness, a new medicine, a loss, a new job or a baby.
2. Log two weeks of bedtimes, wake times and how rested you felt, with notes on caffeine, alcohol, exercise and stress.
3. List other symptoms, even ones that seem unrelated, and all medicines and supplements you take.
4. Ask a partner whether you snore loudly or seem to stop breathing in your sleep.

A sleep tracker can help with step 2. It shows whether you sleep as long as you think, how much your bedtime moves, and whether your resting heart rate and HRV shift after alcohol, late nights or illness. But a 2024 Sleep Research Society review found consumer devices still misclassify time awake during the night and can work less well for some people. A tracker estimates sleep. It cannot find the cause of tiredness or rule anything out.

If your notes point to a habit, such as late caffeine, our 14-night sleep experiment shows how to test one change at a time. If any of the GP signs above apply, see a doctor first.

Frequently asked questions

Why am I always tired even though I sleep 8 hours?

Time in bed is not the same as good sleep. Alcohol, caffeine, stress or an irregular schedule can leave you tired after 8 hours, and so can sleep apnoea, insomnia, depression, anaemia, thyroid problems and ME/CFS. If you have been tired for a few weeks without a clear reason, the NHS advises seeing a GP.

What is the most common cause of constant tiredness?

Sleep and lifestyle: not enough sleep, irregular sleep times, alcohol, caffeine, stress and too little activity. Among people who see a family doctor mainly for tiredness, a 2016 review of 26 studies found depression was the most common diagnosis, in 18.5%. Serious physical disease was rare.

What are the red flags for fatigue?

See a doctor promptly if tiredness comes with unexplained weight loss, mood changes, strong thirst and peeing more, snoring with pauses in breathing, coughing up blood, difficulty swallowing, bleeding from the back passage, a breast lump, or night sweats with swollen glands. Palpitations with chest pain or fainting, or thoughts of harming yourself, need urgent help.

Why am I so exhausted by everything?

Feeling drained by everyday tasks often comes from stress, poor sleep or a difficult life event. It can also be a sign of depression, which the NHS says can cause lack of energy, disturbed sleep and loss of interest. If you have felt this way most of the day, every day, for more than 2 weeks, see a GP.

What blood tests check why you are tired?

The NHS says you may need blood tests to check for anaemia, diabetes and thyroid problems. A full blood count looks for anaemia, and thyroid tests measure hormone levels. Which tests you need depends on your symptoms and history, so let a doctor decide rather than starting supplements to guess the cause.

Can a sleep tracker tell me why I am tired?

No. A tracker estimates how long and how regularly you sleep and shows trends in resting heart rate and HRV, which can be useful to bring to a GP. It cannot diagnose sleep apnoea, anaemia, thyroid problems, depression or any other cause of tiredness, and a good score does not mean you are fine.

This article is for general information and is not medical advice. PulseRing Pro is a wellness device, not a medical device, and does not diagnose or treat any condition. If you are worried about your health, speak to your GP or a qualified clinician.