Why Am I Always Tired No Matter How Much I Sleep? (UK Guide)

Feeling constantly tired despite getting what seems like enough sleep is a surprisingly common issue. Many people across the UK report waking up groggy, relying heavily on caffeine to function, and struggling to stay alert throughout the day. But if you're getting the NHS-recommended 7 to 9 hours of sleep per night, why might you still feel exhausted?

This guide explores the hidden causes of persistent fatigue, from poor sleep quality and disrupted circadian rhythms to underlying health issues. It also offers practical UK-specific advice on what to do about it.

Is Six Hours of Sleep Enough?

Many people who feel constantly tired are simply not getting enough sleep, even if they think they are. The NHS recommends 7 to 9 hours of sleep per night for most adults. While some individuals may function on six hours, this is not the norm.

Studies have shown that sleep duration below 7 hours on a regular basis increases the risk of:

• Poor cognitive function

• Mood disturbances

• Weakened immune function

• Weight gain and metabolic issues

Chronic short sleep also disrupts the body's ability to cycle through all the stages of sleep, especially deep sleep (slow-wave) and REM sleep, both of which are essential for physical and mental restoration.

For those looking to optimise sleep quantity and quality, see our full breakdown: Is 6 Hours of Sleep Enough?

How to Tell if You’re Not Getting Restorative Sleep

It is possible to spend eight or even nine hours in bed and still be sleep-deprived. The real question is whether your sleep is restorative. Poor-quality sleep can mimic the effects of too little sleep, leaving you feeling worn out no matter how early you went to bed.

Here are some signs your sleep might not be serving you well:

• You need an alarm to wake up and still feel groggy when it goes off

• You feel drowsy by mid-morning or experience an afternoon slump

• You rely on caffeine, sugar, or energy drinks just to get through the day

• You oversleep or nap excessively on weekends to 'catch up'

• You struggle with mental fog, poor memory, or mood swings

These signs suggest your body is not getting enough restorative sleep stages, particularly deep sleep and REM. Even if your total sleep time seems sufficient, disrupted sleep architecture or poor habits may be undermining its benefits. Addressing this often means improving both sleep hygiene and the underlying factors that influence quality.

Poor Sleep Quality: Getting Time but Not Rest

Quantity of sleep is only half the picture. You may spend 8 hours in bed but get fragmented, low-quality sleep. Common disruptors include:

1. Sleep Apnoea (Including Undiagnosed Cases)

Obstructive sleep apnoea (OSA) causes brief pauses in breathing during sleep, resulting in dozens or even hundreds of micro-awakenings per night. People with sleep apnoea often snore, wake up with headaches, and feel unrefreshed in the morning despite long sleep durations.

The NHS provides assessments and CPAP treatments for moderate to severe cases. If you're a loud snorer or often wake up gasping for air, ask your GP for a referral to a sleep clinic.

2. Restless Leg Syndrome (RLS)

RLS causes uncomfortable sensations in the legs and an irresistible urge to move them, particularly in the evening or at night. This disrupts sleep onset and can lead to multiple night awakenings.

3. Stress, Anxiety, or Night-Time Rumination

Night-time anxiety can drastically reduce sleep efficiency. You may be spending 8 hours in bed but tossing and turning for much of it. High cortisol levels can keep your nervous system in a state of alertness long after the lights go out.

4. Blue Light and Late-Night Stimulation

Exposure to blue light from phones, tablets, and televisions suppresses melatonin production and shifts your circadian rhythm later. Even if you fall asleep, your body may not enter deep sleep stages promptly.

Medical Causes of Persistent Fatigue

Vegetarians may suffer from low iron, causing tiredness

Sometimes, the issue is not sleep itself but an underlying medical condition affecting your energy levels.

Thyroid Dysfunction

Hypothyroidism is a major cause of chronic fatigue, particularly among women. It results from low levels of thyroid hormones, which regulate metabolism and energy.

Symptoms include tiredness, weight gain, cold intolerance, and dry skin. Blood tests through the NHS can assess your TSH, T3, and T4 levels.

Iron Deficiency or Low Ferritin

Even if your haemoglobin is normal, low ferritin (your iron storage marker) can lead to profound fatigue, brain fog, and low stamina. Women with heavy periods and people with coeliac disease are particularly at risk.

Ferritin below 50 ng/mL may warrant supplementation, especially if you are symptomatic. Dr Diana Gall, from Doctor-4-U, notes that the symptoms of low iron can also cause mental health issues too:

‘Constant tiredness and lacking energy, one of the most common symptoms, can have a real impact on your mental health and mood as well.’

Vitamin B12 and Folate Deficiencies

Both are essential for nerve health and red blood cell production. Deficiency symptoms include fatigue, numbness or tingling, memory issues, and mood disturbances.

The NHS provides testing for B12 and folate levels, and supplementation is straightforward.

Chronic Fatigue Syndrome / ME

This condition is more complex and involves persistent fatigue that does not improve with rest. Other symptoms include post-exertional malaise, muscle pain, and sleep disturbances.

NHS guidance now recognises ME/CFS as a genuine biomedical condition with specific care pathways.

Mental Health and Exhaustion

Depression is often mistaken for laziness or simply feeling tired. However, chronic fatigue is one of the hallmark symptoms of depressive disorders. Other signs include low motivation, loss of pleasure, poor concentration, and sleep disturbances.

Addressing mental health through therapy or medication often improves both energy and sleep quality. If you suspect this may be a factor, speak to your GP or explore NHS IAPT (Improving Access to Psychological Therapies) services.

Lifestyle Factors That Drain Energy

Even mild dehydration can cause tiredness

Poor Diet and Blood Sugar Spikes

A high-sugar, low-protein diet can cause erratic blood sugar swings, leading to energy crashes. Prioritise:

• Complex carbohydrates (oats, brown rice)

• Healthy fats (avocado, olive oil)

• Protein with every meal

• Limiting processed sugar and refined grains

This helps stabilise energy levels throughout the day and supports restful sleep.

Dehydration

Even mild dehydration can reduce cognitive performance and increase feelings of tiredness. The NHS recommends 6 to 8 glasses of fluid per day.

Lack of Sunlight and Vitamin D

In the UK, especially during winter months, vitamin D deficiency is common. Fatigue is a recognised symptom. Public Health England recommends that everyone considers a daily supplement from October to March.

Could It Be Sleep Inertia?

Sleep inertia is the grogginess you feel immediately upon waking. It is worse when waking from deep sleep or if sleep was insufficient or fragmented.

If this grogginess lasts more than 30 to 60 minutes, it could suggest an issue with sleep architecture. Improving sleep consistency, avoiding alcohol, and getting morning light exposure can all help.

For more, read: Sleep Inertia: What It Is and How to Fix It

When to See a Doctor

Persistent fatigue should not be ignored. See your GP if:

• Tiredness lasts more than four weeks

• It impacts your ability to work or engage socially

• You have unexplained weight loss or gain

• You snore heavily or stop breathing in your sleep

• You have other symptoms like palpitations, dizziness, or brain fog

NHS fatigue assessments often begin with a full blood panel, thyroid function test, and a review of sleep hygiene and mental health.

Final Thoughts: Why Am I Always Tired?

Start by ensuring the fundamentals of good sleep hygiene are in place. Aim for 7 to 9 hours of sleep each night and keep your sleep and wake times consistent, even on weekends.

Caffeine should be limited in the afternoon, ideally avoided after 2 PM, to prevent it from interfering with sleep later on. Diet also plays a key role: a balanced, protein-rich diet supports steady energy levels and better sleep quality. Morning sunlight exposure can help regulate your circadian rhythm, making it easier to fall asleep and wake up naturally.

If needed, consider sleep aids like magnesium or herbal sleeping tablets, especially during periods of heightened stress or disruption.

However, if fatigue persists despite these efforts, it is important to dig deeper. Ongoing tiredness may be a symptom of an underlying issue rather than a stand-alone problem, and finding the root cause is key to restoring energy and well-being.

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Frequently Asked Questions

Why do I still feel tired even after 8 hours of sleep?

You may be experiencing poor sleep quality rather than insufficient sleep duration. Conditions like sleep apnoea, stress, or fragmented sleep can prevent your body from reaching the deep and REM sleep stages that are critical for feeling rested.

Can sleep apnoea go undiagnosed?

How do I know if I’m sleep-deprived?

Could vitamin deficiencies make me tired?

Does anxiety or depression cause fatigue?

Are herbal sleep aids effective?

Should I see a doctor if I’m always tired?