Constant fatigue: causes and what to check first

Team nutritionist · · Updated September 25, 2026

Tired woman lying on a bed — causes of constant fatigue

You get tired, you rest. But what if the tiredness does not go away for weeks? We look at the most common causes and what you can change today.

Fatigue is one of the most common complaints people bring to a doctor. In most cases its causes lie in lifestyle: lack of sleep, stress, diet, too little movement. But sometimes it is caused by conditions that need to be identified and managed with a specialist.

Which habits cause constant fatigue?

  • Sleep. Do you sleep 7–9 hours and wake up rested? If not, start with your sleep routine.
  • Food. A skipped breakfast and sugary snacks cause energy spikes and crashes. More in "Breakfast for energy".
  • Water. Even mild dehydration feels like sluggishness and a headache (how much to drink).
  • Movement. It sounds paradoxical, but regular light activity reduces fatigue. Start with a daily walk.
  • Stress. Constant tension drains you as much as physical work (breathing techniques).
  • Caffeine and alcohol. Both disrupt the structure of sleep, even if you fall asleep without trouble.

When should you see a doctor about fatigue?

If you have sorted out your sleep and routine but the fatigue lasts more than 2–4 weeks, be sure to see a GP. Common medical causes of fatigue include iron deficiency (anaemia), thyroid problems, vitamin deficiencies, diabetes, sleep apnoea and depression. Most of them can be detected with simple tests.

Where do you start to get your energy back?

Do not try to change everything at once. Choose one action a week: go to bed 30 minutes earlier, have protein for breakfast, walk for 20 minutes. In a month, four small steps will make a noticeable difference to how you feel.

Once serious causes have been ruled out and your routine is in order, you can also support yourself with LifeWave products: Energy Enhancer patches for natural energy without caffeine, Cellergize Morning — a morning drink with vitamins and minerals, and X39 — the flagship patch for energy and recovery. But always start with sleep, food and movement.

Questions and answers

Why am I tired even when I get enough sleep?
Common causes are stress, too little water and movement, skipped breakfasts, as well as iron deficiency, thyroid problems or sleep apnoea. If fatigue lasts more than 2–4 weeks, see a doctor.
What tests should I take for constant fatigue?
Your doctor decides, but a full blood count, iron, thyroid hormones, blood sugar and vitamins are often checked.
Does coffee help with fatigue?
Coffee gives a short boost, but in large amounts or after lunch it disrupts sleep, which only makes fatigue worse.

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