Tired All the Time? Common Causes and When to See a GP

Feeling tired all the time is very common, and it usually has an everyday cause such as poor sleep, stress or diet. Sometimes it's a sign of something your GP should check, such as low iron or a thyroid problem. Here are the common causes, simple habits to try, and when to see a doctor.

Common reasons you feel tired all the time

• Sleep: not enough, or broken sleep, even if you spend 8 hours in bed

• Stress and worry: being "always on" is tiring in itself

• Diet: skipping meals, lots of sugar or caffeine, or not drinking enough water

• Low activity: sitting for most of the day

• Low nutrient levels: such as iron, vitamin B12 or vitamin D

• Life changes: a new baby, shift work, the menopause

Simple habits to try

• Go to bed and get up at the same time each day

• Cut down on screens and caffeine in the evening

• Eat regular meals with protein, fibre and vegetables

• Walk every day, even for 20 minutes

• Drink enough water

Nutrients and tiredness

Some nutrients have authorised claims linked to tiredness. For example, iron, magnesium and vitamin B12 each contribute to the reduction of tiredness and fatigue. If you think your diet may be low in one of them, ask your GP about a blood test before you buy a supplement.

We stock magnesium and vitamin B12 supplements, including Lamberts Magnesium 375mg and Jarrow Methyl B-12. Browse the range on our Sleep & Energy page.

When to see a GP

See your GP if you've felt tired for several weeks for no obvious reason, or if tiredness comes with:

• unexplained weight loss or weight gain

• feeling low, or losing interest in things

• heavy periods, or feeling breathless

• loud snoring or stopping breathing in your sleep

• any other symptoms that worry you

Tiredness has many possible causes, and a GP can help you find yours.

Food supplements should not replace a varied, balanced diet and a healthy lifestyle.

Written by the Nompharma team, BioCity, Nottingham. Product facts checked against the manufacturer's label; health wording limited to the claims authorised in Great Britain. Last updated November 2026.